diff --git a/CMakeLists.txt b/CMakeLists.txt
index 97a3641f5..7027e3300 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -527,12 +527,12 @@ ENDIF()
 MARK_AS_ADVANCED ( ASSIMP_BUILD_ARCHITECTURE ASSIMP_BUILD_COMPILER )
 
 SET ( ASSIMP_BUILD_NONFREE_C4D_IMPORTER OFF CACHE BOOL
-  "Build the C4D importer, which relies on the non-free Melange SDK."
+  "Build the C4D importer, which relies on the non-free Cineware SDK."
 )
 
 IF (ASSIMP_BUILD_NONFREE_C4D_IMPORTER)
   IF ( MSVC )
-    SET(C4D_INCLUDES "${CMAKE_CURRENT_SOURCE_DIR}/contrib/Melange/includes")
+    SET(C4D_INCLUDES "${CMAKE_CURRENT_SOURCE_DIR}/contrib/Cineware/includes")
 
     # pick the correct prebuilt library
     IF(MSVC15)
@@ -551,22 +551,23 @@ IF (ASSIMP_BUILD_NONFREE_C4D_IMPORTER)
       )
     ENDIF()
 
-    SET(C4D_LIB_BASE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/contrib/Melange/libraries/win")
+    SET(C4D_LIB_BASE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/contrib/Cineware/libraries/win")
 
     SET(C4D_DEBUG_LIBRARIES
-      "${C4D_LIB_BASE_PATH}/melangelib${C4D_LIB_POSTFIX}/melangelib_debug.lib"
+      "${C4D_LIB_BASE_PATH}/cinewarelib${C4D_LIB_POSTFIX}/cinewarelib_debug.lib"
       "${C4D_LIB_BASE_PATH}/jpeglib${C4D_LIB_POSTFIX}/jpeglib_debug.lib"
     )
     SET(C4D_RELEASE_LIBRARIES
-      "${C4D_LIB_BASE_PATH}/melangelib${C4D_LIB_POSTFIX}/melangelib_release.lib"
+      "${C4D_LIB_BASE_PATH}/cinewarelib${C4D_LIB_POSTFIX}/cinewarelib_release.lib"
       "${C4D_LIB_BASE_PATH}/jpeglib${C4D_LIB_POSTFIX}/jpeglib_release.lib"
     )
 
-    # winsock and winmm are necessary dependencies of melange (this is undocumented, but true.)
+    # winsock and winmm are necessary (and undocumented) dependencies of Cineware SDK because
+    # it can be used to communicate with a running Cinema 4D instance
     SET(C4D_EXTRA_LIBRARIES WSock32.lib Winmm.lib)
   ELSE ()
     MESSAGE( FATAL_ERROR
-      "C4D is currently only available on Windows with melange SDK installed in contrib/Melange"
+      "C4D is currently only available on Windows with Cineware SDK installed in contrib/Cineware"
     )
   ENDIF ()
 ELSE ()
diff --git a/Readme.md b/Readme.md
index 81fd9fd9d..f2ea4b094 100644
--- a/Readme.md
+++ b/Readme.md
@@ -66,9 +66,9 @@ Open Asset Import Library is implemented in C++. The directory structure looks l
 
 The source code is organized in the following way:
 
-	code/Common		The base implementation for importers and the infrastructure
-	code/PostProcessing	The post-processing steps
-	code/<FormatName>	Implementation for import and export for the format
+	code/Common			The base implementation for importers and the infrastructure
+	code/PostProcessing		The post-processing steps
+	code/AssetLib/<FormatName>	Implementation for import and export for the format
 
 ### Where to get help ###
 For more information, visit [our website](http://assimp.org/). Or check out the `./doc`- folder, which contains the official documentation in HTML format.
diff --git a/code/AssetLib/3DS/3DSConverter.cpp b/code/AssetLib/3DS/3DSConverter.cpp
index 12ac7e69e..aca16b0d6 100644
--- a/code/AssetLib/3DS/3DSConverter.cpp
+++ b/code/AssetLib/3DS/3DSConverter.cpp
@@ -69,7 +69,7 @@ void Discreet3DSImporter::ReplaceDefaultMaterial() {
     for (unsigned int i = 0; i < mScene->mMaterials.size(); ++i) {
         std::string s = mScene->mMaterials[i].mName;
         for (std::string::iterator it = s.begin(); it != s.end(); ++it) {
-            *it = static_cast<char>(::tolower(*it));
+            *it = static_cast<char>(::tolower(static_cast<unsigned char>(*it)));
         }
 
         if (std::string::npos == s.find("default")) continue;
@@ -212,7 +212,7 @@ void Discreet3DSImporter::ConvertMaterial(D3DS::Material &oldMat,
         mat.AddProperty(&tex, AI_MATKEY_GLOBAL_BACKGROUND_IMAGE);
 
         // Be sure this is only done for the first material
-        mBackgroundImage = std::string("");
+        mBackgroundImage = std::string();
     }
 
     // At first add the base ambient color of the scene to the material
diff --git a/code/AssetLib/3DS/3DSExporter.cpp b/code/AssetLib/3DS/3DSExporter.cpp
index 108d917d1..92a6d5aa7 100644
--- a/code/AssetLib/3DS/3DSExporter.cpp
+++ b/code/AssetLib/3DS/3DSExporter.cpp
@@ -102,13 +102,14 @@ private:
 // preserves the mesh's given name if it has one. |index| is the index
 // of the mesh in |aiScene::mMeshes|.
 std::string GetMeshName(const aiMesh &mesh, unsigned int index, const aiNode &node) {
-    static const std::string underscore = "_";
+    static const char underscore = '_';
     char postfix[10] = { 0 };
     ASSIMP_itoa10(postfix, index);
 
     std::string result = node.mName.C_Str();
     if (mesh.mName.length > 0) {
-        result += underscore + mesh.mName.C_Str();
+        result += underscore;
+        result += mesh.mName.C_Str();
     }
     return result + underscore + postfix;
 }
@@ -378,7 +379,7 @@ void Discreet3DSExporter::WriteTexture(const aiMaterial &mat, aiTextureType type
 
     // TODO: handle embedded textures properly
     if (path.data[0] == '*') {
-        ASSIMP_LOG_ERROR("Ignoring embedded texture for export: " + std::string(path.C_Str()));
+        ASSIMP_LOG_ERROR("Ignoring embedded texture for export: ", path.C_Str());
         return;
     }
 
diff --git a/code/AssetLib/3DS/3DSHelper.h b/code/AssetLib/3DS/3DSHelper.h
index f3f9efb25..1930c0c40 100644
--- a/code/AssetLib/3DS/3DSHelper.h
+++ b/code/AssetLib/3DS/3DSHelper.h
@@ -61,20 +61,10 @@ namespace D3DS {
 #include <assimp/Compiler/pushpack1.h>
 
 // ---------------------------------------------------------------------------
-/** Discreet3DS class: Helper class for loading 3ds files. Defines chunks
-*  and data structures.
+/** Defines chunks and data structures.
 */
-class Discreet3DS {
-private:
-    Discreet3DS() AI_NO_EXCEPT {
-        // empty
-    }
+namespace Discreet3DS {
 
-    ~Discreet3DS() {
-        // empty
-    }
-
-public:
     //! data structure for a single chunk in a .3ds file
     struct Chunk {
         uint16_t Flag;
@@ -314,7 +304,7 @@ public:
         // camera sub-chunks
         CHUNK_CAM_RANGES = 0x4720
     };
-};
+}
 
 // ---------------------------------------------------------------------------
 /** Helper structure representing a 3ds mesh face */
diff --git a/code/AssetLib/3DS/3DSLoader.cpp b/code/AssetLib/3DS/3DSLoader.cpp
index 0a64f6870..b5e6f749b 100644
--- a/code/AssetLib/3DS/3DSLoader.cpp
+++ b/code/AssetLib/3DS/3DSLoader.cpp
@@ -143,7 +143,13 @@ void Discreet3DSImporter::SetupProperties(const Importer * /*pImp*/) {
 // Imports the given file into the given scene structure.
 void Discreet3DSImporter::InternReadFile(const std::string &pFile,
         aiScene *pScene, IOSystem *pIOHandler) {
-    StreamReaderLE theStream(pIOHandler->Open(pFile, "rb"));
+
+    auto theFile = pIOHandler->Open(pFile, "rb");
+    if (!theFile) {
+        throw DeadlyImportError("3DS: Could not open ", pFile);
+    }
+
+    StreamReaderLE theStream(theFile);
 
     // We should have at least one chunk
     if (theStream.GetRemainingSize() < 16) {
@@ -164,7 +170,7 @@ void Discreet3DSImporter::InternReadFile(const std::string &pFile,
     mRootNode->mHierarchyIndex = -1;
     mRootNode->mParent = nullptr;
     mMasterScale = 1.0f;
-    mBackgroundImage = "";
+    mBackgroundImage = std::string();
     bHasBG = false;
     bIsPrj = false;
 
@@ -299,7 +305,7 @@ void Discreet3DSImporter::ParseEditorChunk() {
         // print the version number
         char buff[10];
         ASSIMP_itoa10(buff, stream->GetI2());
-        ASSIMP_LOG_INFO_F(std::string("3DS file format version: "), buff);
+        ASSIMP_LOG_INFO("3DS file format version: ", buff);
     } break;
     };
     ASSIMP_3DS_END_CHUNK();
@@ -928,7 +934,7 @@ void Discreet3DSImporter::ParseFaceChunk() {
             }
         }
         if (0xcdcdcdcd == idx) {
-            ASSIMP_LOG_ERROR_F("3DS: Unknown material: ", sz);
+            ASSIMP_LOG_ERROR("3DS: Unknown material: ", sz);
         }
 
         // Now continue and read all material indices
@@ -981,9 +987,9 @@ void Discreet3DSImporter::ParseMeshChunk() {
         mMesh.mMat.a3 = stream->GetF4();
         mMesh.mMat.b3 = stream->GetF4();
         mMesh.mMat.c3 = stream->GetF4();
-        mMesh.mMat.d1 = stream->GetF4();
-        mMesh.mMat.d2 = stream->GetF4();
-        mMesh.mMat.d3 = stream->GetF4();
+        mMesh.mMat.a4 = stream->GetF4();
+        mMesh.mMat.b4 = stream->GetF4();
+        mMesh.mMat.c4 = stream->GetF4();
     } break;
 
     case Discreet3DS::CHUNK_MAPLIST: {
diff --git a/code/AssetLib/3MF/3MFXmlTags.h b/code/AssetLib/3MF/3MFXmlTags.h
index 3996c60e5..d447556d6 100644
--- a/code/AssetLib/3MF/3MFXmlTags.h
+++ b/code/AssetLib/3MF/3MFXmlTags.h
@@ -44,63 +44,66 @@ namespace Assimp {
 namespace D3MF {
 
 namespace XmlTag {
+    // Root tag
+    const char* const RootTag = "3MF";
+
     // Meta-data
-    static const std::string meta = "metadata";
-    static const std::string meta_name = "name";
+    const char* const meta = "metadata";
+    const char* const meta_name = "name";
 
     // Model-data specific tags
-    static const std::string model = "model";
-    static const std::string model_unit = "unit";
-    static const std::string metadata = "metadata";
-    static const std::string resources = "resources";
-    static const std::string object = "object";
-    static const std::string mesh = "mesh";
-    static const std::string components = "components";
-    static const std::string component = "component";
-    static const std::string vertices = "vertices";
-    static const std::string vertex = "vertex";
-    static const std::string triangles = "triangles";
-    static const std::string triangle = "triangle";
-    static const std::string x = "x";
-    static const std::string y = "y";
-    static const std::string z = "z";
-    static const std::string v1 = "v1";
-    static const std::string v2 = "v2";
-    static const std::string v3 = "v3";
-    static const std::string id = "id";
-    static const std::string pid = "pid";
-    static const std::string pindex = "pindex";
-    static const std::string p1 = "p1";
-    static const std::string name = "name";
-    static const std::string type = "type";
-    static const std::string build = "build";
-    static const std::string item = "item";
-    static const std::string objectid = "objectid";
-    static const std::string transform = "transform";
+    const char* const model = "model";
+    const char* const model_unit = "unit";
+    const char* const metadata = "metadata";
+    const char* const resources = "resources";
+    const char* const object = "object";
+    const char* const mesh = "mesh";
+    const char* const components = "components";
+    const char* const component = "component";
+    const char* const vertices = "vertices";
+    const char* const vertex = "vertex";
+    const char* const triangles = "triangles";
+    const char* const triangle = "triangle";
+    const char* const x = "x";
+    const char* const y = "y";
+    const char* const z = "z";
+    const char* const v1 = "v1";
+    const char* const v2 = "v2";
+    const char* const v3 = "v3";
+    const char* const id = "id";
+    const char* const pid = "pid";
+    const char* const pindex = "pindex";
+    const char* const p1 = "p1";
+    const char* const name = "name";
+    const char* const type = "type";
+    const char* const build = "build";
+    const char* const item = "item";
+    const char* const objectid = "objectid";
+    const char* const transform = "transform";
 
     // Material definitions
-    static const std::string basematerials = "basematerials";
-    static const std::string basematerials_id = "id";
-    static const std::string basematerials_base = "base";
-    static const std::string basematerials_name = "name";
-    static const std::string basematerials_displaycolor = "displaycolor";
+    const char* const basematerials = "basematerials";
+    const char* const basematerials_id = "id";
+    const char* const basematerials_base = "base";
+    const char* const basematerials_name = "name";
+    const char* const basematerials_displaycolor = "displaycolor";
 
     // Meta info tags
-    static const std::string CONTENT_TYPES_ARCHIVE = "[Content_Types].xml";
-    static const std::string ROOT_RELATIONSHIPS_ARCHIVE = "_rels/.rels";
-    static const std::string SCHEMA_CONTENTTYPES = "http://schemas.openxmlformats.org/package/2006/content-types";
-    static const std::string SCHEMA_RELATIONSHIPS = "http://schemas.openxmlformats.org/package/2006/relationships";
-    static const std::string RELS_RELATIONSHIP_CONTAINER = "Relationships";
-    static const std::string RELS_RELATIONSHIP_NODE = "Relationship";
-    static const std::string RELS_ATTRIB_TARGET = "Target";
-    static const std::string RELS_ATTRIB_TYPE = "Type";
-    static const std::string RELS_ATTRIB_ID = "Id";
-    static const std::string PACKAGE_START_PART_RELATIONSHIP_TYPE = "http://schemas.microsoft.com/3dmanufacturing/2013/01/3dmodel";
-    static const std::string PACKAGE_PRINT_TICKET_RELATIONSHIP_TYPE = "http://schemas.microsoft.com/3dmanufacturing/2013/01/printticket";
-    static const std::string PACKAGE_TEXTURE_RELATIONSHIP_TYPE = "http://schemas.microsoft.com/3dmanufacturing/2013/01/3dtexture";
-    static const std::string PACKAGE_CORE_PROPERTIES_RELATIONSHIP_TYPE = "http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-properties";
-    static const std::string PACKAGE_THUMBNAIL_RELATIONSHIP_TYPE = "http://schemas.openxmlformats.org/package/2006/relationships/metadata/thumbnail";
-}
+    const char* const CONTENT_TYPES_ARCHIVE = "[Content_Types].xml";
+    const char* const ROOT_RELATIONSHIPS_ARCHIVE = "_rels/.rels";
+    const char* const SCHEMA_CONTENTTYPES = "http://schemas.openxmlformats.org/package/2006/content-types";
+    const char* const SCHEMA_RELATIONSHIPS = "http://schemas.openxmlformats.org/package/2006/relationships";
+    const char* const RELS_RELATIONSHIP_CONTAINER = "Relationships";
+    const char* const RELS_RELATIONSHIP_NODE = "Relationship";
+    const char* const RELS_ATTRIB_TARGET = "Target";
+    const char* const RELS_ATTRIB_TYPE = "Type";
+    const char* const RELS_ATTRIB_ID = "Id";
+    const char* const PACKAGE_START_PART_RELATIONSHIP_TYPE = "http://schemas.microsoft.com/3dmanufacturing/2013/01/3dmodel";
+    const char* const PACKAGE_PRINT_TICKET_RELATIONSHIP_TYPE = "http://schemas.microsoft.com/3dmanufacturing/2013/01/printticket";
+    const char* const PACKAGE_TEXTURE_RELATIONSHIP_TYPE = "http://schemas.microsoft.com/3dmanufacturing/2013/01/3dtexture";
+    const char* const PACKAGE_CORE_PROPERTIES_RELATIONSHIP_TYPE = "http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-properties";
+    const char* const PACKAGE_THUMBNAIL_RELATIONSHIP_TYPE = "http://schemas.openxmlformats.org/package/2006/relationships/metadata/thumbnail";
+    }
 
 } // Namespace D3MF
 } // Namespace Assimp
diff --git a/code/AssetLib/3MF/D3MFExporter.cpp b/code/AssetLib/3MF/D3MFExporter.cpp
index 4a16a0ad3..76a601cbe 100644
--- a/code/AssetLib/3MF/D3MFExporter.cpp
+++ b/code/AssetLib/3MF/D3MFExporter.cpp
@@ -307,18 +307,26 @@ void D3MFExporter::writeMesh(aiMesh *mesh) {
         return;
     }
 
-    mModelOutput << "<" << XmlTag::mesh << ">" << std::endl;
-    mModelOutput << "<" << XmlTag::vertices << ">" << std::endl;
+    mModelOutput << "<"
+                 << XmlTag::mesh
+                 << ">" << "\n";
+    mModelOutput << "<"
+                 << XmlTag::vertices
+                 << ">" << "\n";
     for (unsigned int i = 0; i < mesh->mNumVertices; ++i) {
         writeVertex(mesh->mVertices[i]);
     }
-    mModelOutput << "</" << XmlTag::vertices << ">" << std::endl;
+    mModelOutput << "</"
+                 << XmlTag::vertices << ">"
+                 << "\n";
 
     const unsigned int matIdx(mesh->mMaterialIndex);
 
     writeFaces(mesh, matIdx);
 
-    mModelOutput << "</" << XmlTag::mesh << ">" << std::endl;
+    mModelOutput << "</"
+                 << XmlTag::mesh << ">"
+                 << "\n";
 }
 
 void D3MFExporter::writeVertex(const aiVector3D &pos) {
@@ -334,27 +342,34 @@ void D3MFExporter::writeFaces(aiMesh *mesh, unsigned int matIdx) {
     if (!mesh->HasFaces()) {
         return;
     }
-    mModelOutput << "<" << XmlTag::triangles << ">" << std::endl;
+    mModelOutput << "<"
+                 << XmlTag::triangles << ">"
+                 << "\n";
     for (unsigned int i = 0; i < mesh->mNumFaces; ++i) {
         aiFace &currentFace = mesh->mFaces[i];
         mModelOutput << "<" << XmlTag::triangle << " v1=\"" << currentFace.mIndices[0] << "\" v2=\""
                      << currentFace.mIndices[1] << "\" v3=\"" << currentFace.mIndices[2]
                      << "\" pid=\"1\" p1=\"" + ai_to_string(matIdx) + "\" />";
-        mModelOutput << std::endl;
+        mModelOutput << "\n";
     }
-    mModelOutput << "</" << XmlTag::triangles << ">";
-    mModelOutput << std::endl;
+    mModelOutput << "</"
+                 << XmlTag::triangles
+                 << ">";
+    mModelOutput << "\n";
 }
 
 void D3MFExporter::writeBuild() {
-    mModelOutput << "<" << XmlTag::build << ">" << std::endl;
+    mModelOutput << "<"
+                 << XmlTag::build
+                 << ">"
+                 << "\n";
 
     for (size_t i = 0; i < mBuildItems.size(); ++i) {
         mModelOutput << "<" << XmlTag::item << " objectid=\"" << i + 2 << "\"/>";
-        mModelOutput << std::endl;
+        mModelOutput << "\n";
     }
     mModelOutput << "</" << XmlTag::build << ">";
-    mModelOutput << std::endl;
+    mModelOutput << "\n";
 }
 
 void D3MFExporter::zipContentType(const std::string &filename) {
diff --git a/code/AssetLib/3MF/D3MFImporter.cpp b/code/AssetLib/3MF/D3MFImporter.cpp
index f4ddb6054..747af7cfc 100644
--- a/code/AssetLib/3MF/D3MFImporter.cpp
+++ b/code/AssetLib/3MF/D3MFImporter.cpp
@@ -42,6 +42,8 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #ifndef ASSIMP_BUILD_NO_3MF_IMPORTER
 
 #include "D3MFImporter.h"
+#include "3MFXmlTags.h"
+#include "D3MFOpcPackage.h"
 
 #include <assimp/StringComparison.h>
 #include <assimp/StringUtils.h>
@@ -51,17 +53,15 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/scene.h>
 #include <assimp/DefaultLogger.hpp>
 #include <assimp/IOSystem.hpp>
+#include <assimp/fast_atof.h>
+
 #include <cassert>
 #include <map>
 #include <memory>
 #include <string>
 #include <vector>
-
-#include "3MFXmlTags.h"
-#include "D3MFOpcPackage.h"
-#include <assimp/fast_atof.h>
-
 #include <iomanip>
+#include <string.h>
 
 namespace Assimp {
 namespace D3MF {
@@ -72,32 +72,39 @@ enum class ResourceType {
     RT_Unknown
 }; // To be extended with other resource types (eg. material extension resources like Texture2d, Texture2dGroup...)
 
-class Resource
-{
+class Resource {
 public:
-    Resource(int id) :
-            mId(id) {}
-
-    virtual ~Resource() {}
-
     int mId;
 
-    virtual ResourceType getType() {
+    Resource(int id) :
+            mId(id) {
+        // empty
+    }
+
+    virtual ~Resource() {
+        // empty
+    }
+
+    virtual ResourceType getType() const {
         return ResourceType::RT_Unknown;
     }
 };
 
 class BaseMaterials : public Resource {
 public:
-    BaseMaterials(int id) :
-            Resource(id),
-            mMaterials(),
-            mMaterialIndex() {}
-
     std::vector<aiMaterial *> mMaterials;
     std::vector<unsigned int> mMaterialIndex;
 
-    virtual ResourceType getType() {
+    BaseMaterials(int id) :
+            Resource(id),
+            mMaterials(),
+            mMaterialIndex() {
+        // empty
+    }
+
+    ~BaseMaterials() = default;
+
+    ResourceType getType() const override {
         return ResourceType::RT_BaseMaterials;
     }
 };
@@ -109,24 +116,26 @@ struct Component {
 
 class Object : public Resource {
 public:
-    std::vector<aiMesh*> mMeshes;
+    std::vector<aiMesh *> mMeshes;
     std::vector<unsigned int> mMeshIndex;
     std::vector<Component> mComponents;
     std::string mName;
 
     Object(int id) :
             Resource(id),
-            mName(std::string("Object_") + ai_to_string(id)) {}
+            mName(std::string("Object_") + ai_to_string(id)) {
+        // empty
+    }
 
-    virtual ResourceType getType() {
+    ~Object() = default;
+
+    ResourceType getType() const override {
         return ResourceType::RT_Object;
     }
 };
 
-
 class XmlSerializer {
 public:
-
     XmlSerializer(XmlParser *xmlParser) :
             mResourcesDictionnary(),
             mMaterialCount(0),
@@ -136,7 +145,7 @@ public:
     }
 
     ~XmlSerializer() {
-        for (auto it = mResourcesDictionnary.begin(); it != mResourcesDictionnary.end(); it++) {
+        for (auto it = mResourcesDictionnary.begin(); it != mResourcesDictionnary.end(); ++it ) {
             delete it->second;
         }
     }
@@ -146,28 +155,28 @@ public:
             return;
         }
 
-        scene->mRootNode = new aiNode("3MF");
+        scene->mRootNode = new aiNode(XmlTag::RootTag);
 
-        XmlNode node = mXmlParser->getRootNode().child("model");
+        XmlNode node = mXmlParser->getRootNode().child(XmlTag::model);
         if (node.empty()) {
             return;
         }
-        XmlNode resNode = node.child("resources");
-        for (XmlNode currentNode = resNode.first_child(); currentNode; currentNode = currentNode.next_sibling()) {
-            const std::string &currentNodeName = currentNode.name();
-            if (currentNodeName == D3MF::XmlTag::object) {
-                ReadObject(currentNode);;
-            } else if (currentNodeName == D3MF::XmlTag::basematerials) {
+        XmlNode resNode = node.child(XmlTag::resources);
+        for (auto &currentNode : resNode.children()) {
+            const std::string currentNodeName = currentNode.name();
+            if (currentNodeName == XmlTag::object) {
+                ReadObject(currentNode);
+            } else if (currentNodeName == XmlTag::basematerials) {
                 ReadBaseMaterials(currentNode);
-            } else if (currentNodeName == D3MF::XmlTag::meta) {
+            } else if (currentNodeName == XmlTag::meta) {
                 ReadMetadata(currentNode);
             }
         }
 
-        XmlNode buildNode = node.child("build");
-        for (XmlNode currentNode = buildNode.first_child(); currentNode; currentNode = currentNode.next_sibling()) {
-            const std::string &currentNodeName = currentNode.name();
-            if (currentNodeName == D3MF::XmlTag::item) {
+        XmlNode buildNode = node.child(XmlTag::build);
+        for (auto &currentNode : buildNode.children()) {
+            const std::string currentNodeName = currentNode.name();
+            if (currentNodeName == XmlTag::item) {
                 int objectId = -1;
                 std::string transformationMatrixStr;
                 aiMatrix4x4 transformationMatrix;
@@ -186,10 +195,9 @@ public:
             }
         }
 
-
         // import the metadata
         if (!mMetaData.empty()) {
-            const size_t numMeta(mMetaData.size());
+            const size_t numMeta = mMetaData.size();
             scene->mMetaData = aiMetadata::Alloc(static_cast<unsigned int>(numMeta));
             for (size_t i = 0; i < numMeta; ++i) {
                 aiString val(mMetaData[i].value);
@@ -201,22 +209,22 @@ public:
         scene->mNumMeshes = static_cast<unsigned int>(mMeshCount);
         if (scene->mNumMeshes != 0) {
             scene->mMeshes = new aiMesh *[scene->mNumMeshes]();
-            for (auto it = mResourcesDictionnary.begin(); it != mResourcesDictionnary.end(); it++) {
+            for (auto it = mResourcesDictionnary.begin(); it != mResourcesDictionnary.end(); ++it) {
                 if (it->second->getType() == ResourceType::RT_Object) {
-                    Object *obj = static_cast<Object*>(it->second);
+                    Object *obj = static_cast<Object *>(it->second);
+                    ai_assert(nullptr != obj);
                     for (unsigned int i = 0; i < obj->mMeshes.size(); ++i) {
                         scene->mMeshes[obj->mMeshIndex[i]] = obj->mMeshes[i];
                     }
                 }
             }
         }
-        
 
         // import the materials
-        scene->mNumMaterials = static_cast<unsigned int>(mMaterialCount);
+        scene->mNumMaterials = mMaterialCount;
         if (scene->mNumMaterials != 0) {
             scene->mMaterials = new aiMaterial *[scene->mNumMaterials];
-            for (auto it = mResourcesDictionnary.begin(); it != mResourcesDictionnary.end(); it++) {
+            for (auto it = mResourcesDictionnary.begin(); it != mResourcesDictionnary.end(); ++it) {
                 if (it->second->getType() == ResourceType::RT_BaseMaterials) {
                     BaseMaterials *baseMaterials = static_cast<BaseMaterials *>(it->second);
                     for (unsigned int i = 0; i < baseMaterials->mMaterials.size(); ++i) {
@@ -228,35 +236,36 @@ public:
     }
 
 private:
+    void addObjectToNode(aiNode *parent, Object *obj, aiMatrix4x4 nodeTransform) {
+        ai_assert(nullptr != obj);
 
-    void addObjectToNode(aiNode* parent, Object* obj, aiMatrix4x4 nodeTransform) {
         aiNode *sceneNode = new aiNode(obj->mName);
         sceneNode->mNumMeshes = static_cast<unsigned int>(obj->mMeshes.size());
         sceneNode->mMeshes = new unsigned int[sceneNode->mNumMeshes];
         std::copy(obj->mMeshIndex.begin(), obj->mMeshIndex.end(), sceneNode->mMeshes);
 
         sceneNode->mTransformation = nodeTransform;
-
-        parent->addChildren(1, &sceneNode);
+        if (nullptr != parent) {
+            parent->addChildren(1, &sceneNode);
+        }
 
         for (size_t i = 0; i < obj->mComponents.size(); ++i) {
             Component c = obj->mComponents[i];
             auto it = mResourcesDictionnary.find(c.mObjectId);
             if (it != mResourcesDictionnary.end() && it->second->getType() == ResourceType::RT_Object) {
-                addObjectToNode(sceneNode, static_cast<Object*>(it->second), c.mTransformation);
+                addObjectToNode(sceneNode, static_cast<Object *>(it->second), c.mTransformation);
             }
-            
         }
     }
 
-    bool getNodeAttribute(const XmlNode& node, const std::string& attribute, std::string& value) {
+    bool getNodeAttribute(const XmlNode &node, const std::string &attribute, std::string &value) {
         pugi::xml_attribute objectAttribute = node.attribute(attribute.c_str());
         if (!objectAttribute.empty()) {
             value = objectAttribute.as_string();
             return true;
-        } else {
-            return false;
         }
+
+        return false;
     }
 
     bool getNodeAttribute(const XmlNode &node, const std::string &attribute, int &value) {
@@ -265,9 +274,9 @@ private:
         if (ret) {
             value = std::atoi(strValue.c_str());
             return true;
-        } else {
-            return false;
-        }
+        } 
+
+        return false;
     }
 
     aiMatrix4x4 parseTransformMatrix(std::string matrixStr) {
@@ -287,7 +296,7 @@ private:
             }
         }
         if (currentNumber.size() > 0) {
-            float f = std::stof(currentNumber);
+            const float f = std::stof(currentNumber);
             numbers.push_back(f);
         }
 
@@ -311,29 +320,26 @@ private:
         transformMatrix.b4 = numbers[10];
         transformMatrix.c4 = numbers[11];
         transformMatrix.d4 = 1;
+
         return transformMatrix;
     }
 
     void ReadObject(XmlNode &node) {
         int id = -1, pid = -1, pindex = -1;
-        bool hasId = getNodeAttribute(node, D3MF::XmlTag::id, id);
-        //bool hasType = getNodeAttribute(node, D3MF::XmlTag::type, type); not used currently
-        bool hasPid = getNodeAttribute(node, D3MF::XmlTag::pid, pid);
-        bool hasPindex = getNodeAttribute(node, D3MF::XmlTag::pindex, pindex);
-
-        std::string idStr = ai_to_string(id);
-
+        bool hasId = getNodeAttribute(node, XmlTag::id, id);
+        bool hasPid = getNodeAttribute(node, XmlTag::pid, pid);
+        bool hasPindex = getNodeAttribute(node, XmlTag::pindex, pindex);
         if (!hasId) {
             return;
         }
 
         Object *obj = new Object(id);
 
-        for (XmlNode currentNode = node.first_child(); currentNode; currentNode = currentNode.next_sibling()) {
+        for (XmlNode &currentNode : node.children()) {
             const std::string &currentName = currentNode.name();
             if (currentName == D3MF::XmlTag::mesh) {
                 auto mesh = ReadMesh(currentNode);
-                mesh->mName.Set(idStr);
+                mesh->mName.Set(ai_to_string(id));
 
                 if (hasPid) {
                     auto it = mResourcesDictionnary.find(pid);
@@ -347,8 +353,9 @@ private:
                 obj->mMeshIndex.push_back(mMeshCount);
                 mMeshCount++;
             } else if (currentName == D3MF::XmlTag::components) {
-                for (XmlNode currentSubNode = currentNode.first_child(); currentSubNode; currentSubNode = currentSubNode.next_sibling()) {
-                    if (currentSubNode.name() == D3MF::XmlTag::component) {
+                for (XmlNode &currentSubNode : currentNode.children()) {
+                    const std::string subNodeName = currentSubNode.name();
+                    if (subNodeName == D3MF::XmlTag::component) {
                         int objectId = -1;
                         std::string componentTransformStr;
                         aiMatrix4x4 componentTransform;
@@ -356,8 +363,9 @@ private:
                             componentTransform = parseTransformMatrix(componentTransformStr);
                         }
 
-                        if (getNodeAttribute(currentSubNode, D3MF::XmlTag::objectid, objectId))
+                        if (getNodeAttribute(currentSubNode, D3MF::XmlTag::objectid, objectId)) {
                             obj->mComponents.push_back({ objectId, componentTransform });
+                        }
                     }
                 }
             }
@@ -369,21 +377,20 @@ private:
     aiMesh *ReadMesh(XmlNode &node) {
         aiMesh *mesh = new aiMesh();
 
-        for (XmlNode currentNode = node.first_child(); currentNode; currentNode = currentNode.next_sibling()) {
-            const std::string &currentName = currentNode.name();
-            if (currentName == D3MF::XmlTag::vertices) {
+        for (XmlNode &currentNode : node.children()) {
+            const std::string currentName = currentNode.name();
+            if (currentName == XmlTag::vertices) {
                 ImportVertices(currentNode, mesh);
-            } else if (currentName == D3MF::XmlTag::triangles) {
+            } else if (currentName == XmlTag::triangles) {
                 ImportTriangles(currentNode, mesh);
             }
-
         }
 
         return mesh;
     }
 
     void ReadMetadata(XmlNode &node) {
-        pugi::xml_attribute attribute = node.attribute(D3MF::XmlTag::meta_name.c_str());
+        pugi::xml_attribute attribute = node.attribute(D3MF::XmlTag::meta_name);
         const std::string name = attribute.as_string();
         const std::string value = node.value();
         if (name.empty()) {
@@ -398,9 +405,9 @@ private:
 
     void ImportVertices(XmlNode &node, aiMesh *mesh) {
         std::vector<aiVector3D> vertices;
-        for (XmlNode currentNode = node.first_child(); currentNode; currentNode = currentNode.next_sibling()) {
-            const std::string &currentName = currentNode.name();
-            if (currentName == D3MF::XmlTag::vertex) {
+        for (XmlNode &currentNode : node.children()) {
+            const std::string currentName = currentNode.name();
+            if (currentName == XmlTag::vertex) {
                 vertices.push_back(ReadVertex(currentNode));
             }
         }
@@ -412,29 +419,28 @@ private:
 
     aiVector3D ReadVertex(XmlNode &node) {
         aiVector3D vertex;
-        vertex.x = ai_strtof(node.attribute(D3MF::XmlTag::x.c_str()).as_string(), nullptr);
-        vertex.y = ai_strtof(node.attribute(D3MF::XmlTag::y.c_str()).as_string(), nullptr);
-        vertex.z = ai_strtof(node.attribute(D3MF::XmlTag::z.c_str()).as_string(), nullptr);
+        vertex.x = ai_strtof(node.attribute(XmlTag::x).as_string(), nullptr);
+        vertex.y = ai_strtof(node.attribute(XmlTag::y).as_string(), nullptr);
+        vertex.z = ai_strtof(node.attribute(XmlTag::z).as_string(), nullptr);
 
         return vertex;
     }
 
     void ImportTriangles(XmlNode &node, aiMesh *mesh) {
         std::vector<aiFace> faces;
-        for (XmlNode currentNode = node.first_child(); currentNode; currentNode = currentNode.next_sibling()) {
-            const std::string &currentName = currentNode.name();
-            if (currentName == D3MF::XmlTag::triangle) {
+        for (XmlNode &currentNode : node.children()) {
+            const std::string currentName = currentNode.name();
+            if (currentName == XmlTag::triangle) {
                 aiFace face = ReadTriangle(currentNode);
                 faces.push_back(face);
 
-                int pid = 0, p1;
+                int pid = 0, p1 = 0;
                 bool hasPid = getNodeAttribute(currentNode, D3MF::XmlTag::pid, pid);
                 bool hasP1 = getNodeAttribute(currentNode, D3MF::XmlTag::p1, p1);
 
                 if (hasPid && hasP1) {
                     auto it = mResourcesDictionnary.find(pid);
-                    if (it != mResourcesDictionnary.end())
-                    {
+                    if (it != mResourcesDictionnary.end()) {
                         if (it->second->getType() == ResourceType::RT_BaseMaterials) {
                             BaseMaterials *baseMaterials = static_cast<BaseMaterials *>(it->second);
                             mesh->mMaterialIndex = baseMaterials->mMaterialIndex[p1];
@@ -457,9 +463,9 @@ private:
 
         face.mNumIndices = 3;
         face.mIndices = new unsigned int[face.mNumIndices];
-        face.mIndices[0] = static_cast<unsigned int>(std::atoi(node.attribute(D3MF::XmlTag::v1.c_str()).as_string()));
-        face.mIndices[1] = static_cast<unsigned int>(std::atoi(node.attribute(D3MF::XmlTag::v2.c_str()).as_string()));
-        face.mIndices[2] = static_cast<unsigned int>(std::atoi(node.attribute(D3MF::XmlTag::v3.c_str()).as_string()));
+        face.mIndices[0] = static_cast<unsigned int>(std::atoi(node.attribute(XmlTag::v1).as_string()));
+        face.mIndices[1] = static_cast<unsigned int>(std::atoi(node.attribute(XmlTag::v2).as_string()));
+        face.mIndices[2] = static_cast<unsigned int>(std::atoi(node.attribute(XmlTag::v3).as_string()));
 
         return face;
     }
@@ -467,14 +473,14 @@ private:
     void ReadBaseMaterials(XmlNode &node) {
         int id = -1;
         if (getNodeAttribute(node, D3MF::XmlTag::basematerials_id, id)) {
-            BaseMaterials* baseMaterials = new BaseMaterials(id);
+            BaseMaterials *baseMaterials = new BaseMaterials(id);
 
-            for (XmlNode currentNode = node.first_child(); currentNode; currentNode = currentNode.next_sibling())
-            {
-                if (currentNode.name() == D3MF::XmlTag::basematerials_base) {
+            for (XmlNode &currentNode : node.children()) {
+                const std::string currentName = currentNode.name();
+                if (currentName == XmlTag::basematerials_base) {
                     baseMaterials->mMaterialIndex.push_back(mMaterialCount);
                     baseMaterials->mMaterials.push_back(readMaterialDef(currentNode, id));
-                    mMaterialCount++;
+                    ++mMaterialCount;
                 }
             }
 
@@ -488,7 +494,7 @@ private:
         }
 
         //format of the color string: #RRGGBBAA or #RRGGBB (3MF Core chapter 5.1.1)
-        const size_t len(strlen(color));
+        const size_t len = strlen(color);
         if (9 != len && 7 != len) {
             return false;
         }
@@ -517,7 +523,7 @@ private:
     }
 
     void assignDiffuseColor(XmlNode &node, aiMaterial *mat) {
-        const char *color = node.attribute(D3MF::XmlTag::basematerials_displaycolor.c_str()).as_string();
+        const char *color = node.attribute(XmlTag::basematerials_displaycolor).as_string();
         aiColor4D diffuse;
         if (parseColor(color, diffuse)) {
             mat->AddProperty<aiColor4D>(&diffuse, 1, AI_MATKEY_COLOR_DIFFUSE);
@@ -531,7 +537,7 @@ private:
         bool hasName = getNodeAttribute(node, D3MF::XmlTag::basematerials_name, name);
 
         std::string stdMaterialName;
-        std::string strId(ai_to_string(basematerialsId));
+        const std::string strId(ai_to_string(basematerialsId));
         stdMaterialName += "id";
         stdMaterialName += strId;
         stdMaterialName += "_";
@@ -556,13 +562,15 @@ private:
         std::string value;
     };
     std::vector<MetaEntry> mMetaData;
-    std::map<unsigned int, Resource*> mResourcesDictionnary;
+    std::map<unsigned int, Resource *> mResourcesDictionnary;
     unsigned int mMaterialCount, mMeshCount;
     XmlParser *mXmlParser;
 };
 
 } //namespace D3MF
 
+using namespace D3MF;
+
 static const aiImporterDesc desc = {
     "3mf Importer",
     "",
@@ -596,7 +604,7 @@ bool D3MFImporter::CanRead(const std::string &filename, IOSystem *pIOHandler, bo
         if (!ZipArchiveIOSystem::isZipArchive(pIOHandler, filename)) {
             return false;
         }
-        D3MF::D3MFOpcPackage opcPackage(pIOHandler, filename);
+        D3MFOpcPackage opcPackage(pIOHandler, filename);
         return opcPackage.validate();
     }
 
@@ -612,11 +620,11 @@ const aiImporterDesc *D3MFImporter::GetInfo() const {
 }
 
 void D3MFImporter::InternReadFile(const std::string &filename, aiScene *pScene, IOSystem *pIOHandler) {
-    D3MF::D3MFOpcPackage opcPackage(pIOHandler, filename);
+    D3MFOpcPackage opcPackage(pIOHandler, filename);
 
     XmlParser xmlParser;
     if (xmlParser.parse(opcPackage.RootStream())) {
-        D3MF::XmlSerializer xmlSerializer(&xmlParser);
+        XmlSerializer xmlSerializer(&xmlParser);
         xmlSerializer.ImportXml(pScene);
     }
 }
diff --git a/code/AssetLib/3MF/D3MFImporter.h b/code/AssetLib/3MF/D3MFImporter.h
index a65c4102f..811c463b6 100644
--- a/code/AssetLib/3MF/D3MFImporter.h
+++ b/code/AssetLib/3MF/D3MFImporter.h
@@ -47,9 +47,9 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 namespace Assimp {
 
+/// @brief  The 3MF-importer class.
 class D3MFImporter : public BaseImporter {
 public:
-    // BaseImporter interface
     D3MFImporter();
     ~D3MFImporter();
     bool CanRead(const std::string &pFile, IOSystem *pIOHandler, bool checkSig) const;
diff --git a/code/AssetLib/3MF/D3MFOpcPackage.cpp b/code/AssetLib/3MF/D3MFOpcPackage.cpp
index 16e659ea3..dbf4f2e10 100644
--- a/code/AssetLib/3MF/D3MFOpcPackage.cpp
+++ b/code/AssetLib/3MF/D3MFOpcPackage.cpp
@@ -103,9 +103,9 @@ public:
             std::string name = currentNode.name();
             if (name == "Relationship") {
                 OpcPackageRelationshipPtr relPtr(new OpcPackageRelationship());
-                relPtr->id = currentNode.attribute(XmlTag::RELS_ATTRIB_ID.c_str()).as_string();
-                relPtr->type = currentNode.attribute(XmlTag::RELS_ATTRIB_TYPE.c_str()).as_string();
-                relPtr->target = currentNode.attribute(XmlTag::RELS_ATTRIB_TARGET.c_str()).as_string();
+                relPtr->id = currentNode.attribute(XmlTag::RELS_ATTRIB_ID).as_string();
+                relPtr->type = currentNode.attribute(XmlTag::RELS_ATTRIB_TYPE).as_string();
+                relPtr->target = currentNode.attribute(XmlTag::RELS_ATTRIB_TARGET).as_string();
                 if (validateRels(relPtr)) {
                     m_relationShips.push_back(relPtr);
                 }
@@ -160,9 +160,9 @@ D3MFOpcPackage::D3MFOpcPackage(IOSystem *pIOHandler, const std::string &rFile) :
             }
 
         } else if (file == D3MF::XmlTag::CONTENT_TYPES_ARCHIVE) {
-            ASSIMP_LOG_WARN_F("Ignored file of unsupported type CONTENT_TYPES_ARCHIVES", file);
+            ASSIMP_LOG_WARN("Ignored file of unsupported type CONTENT_TYPES_ARCHIVES", file);
         } else {
-            ASSIMP_LOG_WARN_F("Ignored file of unknown type: ", file);
+            ASSIMP_LOG_WARN("Ignored file of unknown type: ", file);
         }
     }
 }
@@ -188,7 +188,7 @@ bool D3MFOpcPackage::validate() {
 std::string D3MFOpcPackage::ReadPackageRootRelationship(IOStream *stream) {
     XmlParser xmlParser;
     if (!xmlParser.parse(stream)) {
-        return "";
+        return std::string();
     }
 
     OpcPackageRelationshipReader reader(xmlParser);
diff --git a/code/AssetLib/AC/ACLoader.cpp b/code/AssetLib/AC/ACLoader.cpp
index cba84e8b0..078c96e32 100644
--- a/code/AssetLib/AC/ACLoader.cpp
+++ b/code/AssetLib/AC/ACLoader.cpp
@@ -116,7 +116,7 @@ inline const char *TAcCheckedLoadFloatArray(const char *buffer, const char *name
     buffer = AcSkipToNextToken(buffer);
     if (0 != name_length) {
         if (0 != strncmp(buffer, name, name_length) || !IsSpace(buffer[name_length])) {
-            ASSIMP_LOG_ERROR("AC3D: Unexpexted token. " + std::string(name) + " was expected.");
+            ASSIMP_LOG_ERROR("AC3D: Unexpected token. ", name, " was expected.");
             return buffer;
         }
         buffer += name_length + 1;
@@ -492,7 +492,7 @@ aiNode *AC3DImporter::ConvertObjectSection(Object &object,
 
                 default:
                     // Coerce unknowns to a polygon and warn
-                    ASSIMP_LOG_WARN_F("AC3D: The type flag of a surface is unknown: ", (*it).flags);
+                    ASSIMP_LOG_WARN("AC3D: The type flag of a surface is unknown: ", (*it).flags);
                     (*it).flags &= ~(Surface::Mask);
                     // fallthrough
 
@@ -690,7 +690,7 @@ aiNode *AC3DImporter::ConvertObjectSection(Object &object,
             if (object.subDiv) {
                 if (configEvalSubdivision) {
                     std::unique_ptr<Subdivider> div(Subdivider::Create(Subdivider::CATMULL_CLARKE));
-                    ASSIMP_LOG_INFO("AC3D: Evaluating subdivision surface: " + object.name);
+                    ASSIMP_LOG_INFO("AC3D: Evaluating subdivision surface: ", object.name);
 
                     std::vector<aiMesh *> cpy(meshes.size() - oldm, nullptr);
                     div->Subdivide(&meshes[oldm], cpy.size(), &cpy.front(), object.subDiv, true);
@@ -698,7 +698,7 @@ aiNode *AC3DImporter::ConvertObjectSection(Object &object,
 
                     // previous meshes are deleted vy Subdivide().
                 } else {
-                    ASSIMP_LOG_INFO("AC3D: Letting the subdivision surface untouched due to my configuration: " + object.name);
+                    ASSIMP_LOG_INFO("AC3D: Letting the subdivision surface untouched due to my configuration: ", object.name);
                 }
             }
         }
@@ -782,7 +782,7 @@ void AC3DImporter::InternReadFile(const std::string &pFile,
     unsigned int version = HexDigitToDecimal(buffer[4]);
     char msg[3];
     ASSIMP_itoa10(msg, 3, version);
-    ASSIMP_LOG_INFO_F("AC3D file format version: ", msg);
+    ASSIMP_LOG_INFO("AC3D file format version: ", msg);
 
     std::vector<Material> materials;
     materials.reserve(5);
diff --git a/code/AssetLib/AC/ACLoader.h b/code/AssetLib/AC/ACLoader.h
index 77de16b8b..5ae2e80bb 100644
--- a/code/AssetLib/AC/ACLoader.h
+++ b/code/AssetLib/AC/ACLoader.h
@@ -123,9 +123,9 @@ public:
     struct Object {
         Object() :
                 type(World),
-                name(""),
+                name(),
                 children(),
-                texture(""),
+                texture(),
                 texRepeat(1.f, 1.f),
                 texOffset(0.0f, 0.0f),
                 rotation(),
diff --git a/code/AssetLib/AMF/AMFImporter.cpp b/code/AssetLib/AMF/AMFImporter.cpp
index 37756aea0..615882b6a 100644
--- a/code/AssetLib/AMF/AMFImporter.cpp
+++ b/code/AssetLib/AMF/AMFImporter.cpp
@@ -205,7 +205,7 @@ void AMFImporter::ParseHelper_FixTruncatedFloatString(const char *pInStr, std::s
 }
 
 static bool ParseHelper_Decode_Base64_IsBase64(const char pChar) {
-    return (isalnum(pChar) || (pChar == '+') || (pChar == '/'));
+    return (isalnum((unsigned char)pChar) || (pChar == '+') || (pChar == '/'));
 }
 
 void AMFImporter::ParseHelper_Decode_Base64(const std::string &pInputBase64, std::vector<uint8_t> &pOutputData) const {
@@ -268,7 +268,8 @@ void AMFImporter::ParseFile(const std::string &pFile, IOSystem *pIOHandler) {
     mXmlParser = new XmlParser();
     if (!mXmlParser->parse(file.get())) {
         delete mXmlParser;
-        throw DeadlyImportError("Failed to create XML reader for file" + pFile + ".");
+        mXmlParser = nullptr;
+        throw DeadlyImportError("Failed to create XML reader for file ", pFile, ".");
     }
 
     // Start reading, search for root tag <amf>
@@ -517,10 +518,6 @@ bool AMFImporter::CanRead(const std::string &pFile, IOSystem *pIOHandler, bool p
     return false;
 }
 
-void AMFImporter::GetExtensionList(std::set<std::string> &pExtensionList) {
-    pExtensionList.insert("amf");
-}
-
 const aiImporterDesc *AMFImporter::GetInfo() const {
     return &Description;
 }
diff --git a/code/AssetLib/AMF/AMFImporter.hpp b/code/AssetLib/AMF/AMFImporter.hpp
index ef61be463..18ef83c24 100644
--- a/code/AssetLib/AMF/AMFImporter.hpp
+++ b/code/AssetLib/AMF/AMFImporter.hpp
@@ -277,7 +277,6 @@ public:
     void ParseHelper_Node_Enter(AMFNodeElementBase *child);
     void ParseHelper_Node_Exit();
     bool CanRead(const std::string &pFile, IOSystem *pIOHandler, bool pCheckSig) const;
-    void GetExtensionList(std::set<std::string> &pExtensionList);
     void InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler);
     const aiImporterDesc *GetInfo() const;
     bool Find_NodeElement(const std::string &pID, const AMFNodeElementBase::EType pType, AMFNodeElementBase **pNodeElement) const;
diff --git a/code/AssetLib/AMF/AMFImporter_Postprocess.cpp b/code/AssetLib/AMF/AMFImporter_Postprocess.cpp
index 036b647e8..43d0de52f 100644
--- a/code/AssetLib/AMF/AMFImporter_Postprocess.cpp
+++ b/code/AssetLib/AMF/AMFImporter_Postprocess.cpp
@@ -428,10 +428,10 @@ void AMFImporter::Postprocess_BuildMeshSet(const AMFMesh &pNodeElement, const st
 
                     if (pBiggerThan != nullptr) {
                         bool found = false;
-
+                        const size_t biggerThan = *pBiggerThan;
                         for (const SComplexFace &face : pFaceList) {
                             for (size_t idx_vert = 0; idx_vert < face.Face.mNumIndices; idx_vert++) {
-                                if (face.Face.mIndices[idx_vert] > *pBiggerThan) {
+                                if (face.Face.mIndices[idx_vert] > biggerThan) {
                                     rv = face.Face.mIndices[idx_vert];
                                     found = true;
                                     break;
diff --git a/code/AssetLib/ASE/ASELoader.cpp b/code/AssetLib/ASE/ASELoader.cpp
index e1b9c5b83..1a42c2f52 100644
--- a/code/AssetLib/ASE/ASELoader.cpp
+++ b/code/AssetLib/ASE/ASELoader.cpp
@@ -614,7 +614,7 @@ void ASEImporter::AddNodes(const std::vector<BaseNode *> &nodes,
             node->mNumChildren++;
 
             // What we did is so great, it is at least worth a debug message
-            ASSIMP_LOG_VERBOSE_DEBUG("ASE: Generating separate target node (" + snode->mName + ")");
+            ASSIMP_LOG_VERBOSE_DEBUG("ASE: Generating separate target node (", snode->mName, ")");
         }
     }
 
diff --git a/code/AssetLib/ASE/ASEParser.cpp b/code/AssetLib/ASE/ASEParser.cpp
index 21ec26593..1f7018b11 100644
--- a/code/AssetLib/ASE/ASEParser.cpp
+++ b/code/AssetLib/ASE/ASEParser.cpp
@@ -498,6 +498,12 @@ void Parser::ParseLV1MaterialListBlock() {
                 ParseLV2MaterialBlock(sMat);
                 continue;
             }
+            if( iDepth == 1 ){
+                // CRUDE HACK: support missing brace after "Ascii Scene Exporter v2.51"
+                LogWarning("Missing closing brace in material list");
+                --filePtr;
+                return;
+            }
         }
         AI_ASE_HANDLE_TOP_LEVEL_SECTION();
     }
@@ -671,7 +677,7 @@ void Parser::ParseLV3MapBlock(Texture &map) {
                 if (!ParseString(temp, "*MAP_CLASS"))
                     SkipToNextToken();
                 if (temp != "Bitmap" && temp != "Normal Bump") {
-                    ASSIMP_LOG_WARN_F("ASE: Skipping unknown map type: ", temp);
+                    ASSIMP_LOG_WARN("ASE: Skipping unknown map type: ", temp);
                     parsePath = false;
                 }
                 continue;
@@ -685,7 +691,7 @@ void Parser::ParseLV3MapBlock(Texture &map) {
                     // Files with 'None' as map name are produced by
                     // an Maja to ASE exporter which name I forgot ..
                     ASSIMP_LOG_WARN("ASE: Skipping invalid map entry");
-                    map.mMapName = "";
+                    map.mMapName = std::string();
                 }
 
                 continue;
@@ -1119,7 +1125,7 @@ void Parser::ParseLV2NodeTransformBlock(ASE::BaseNode &mesh) {
                                          "this is no spot light or target camera");
                     }
                 } else {
-                    ASSIMP_LOG_ERROR("ASE: Unknown node transformation: " + temp);
+                    ASSIMP_LOG_ERROR("ASE: Unknown node transformation: ", temp);
                     // mode = 0
                 }
                 continue;
diff --git a/code/AssetLib/Assbin/AssbinLoader.cpp b/code/AssetLib/Assbin/AssbinLoader.cpp
index d94a9ed7d..d94407e03 100644
--- a/code/AssetLib/Assbin/AssbinLoader.cpp
+++ b/code/AssetLib/Assbin/AssbinLoader.cpp
@@ -671,7 +671,7 @@ void AssbinImporter::ReadBinaryScene(IOStream *stream, aiScene *scene) {
 void AssbinImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) {
     IOStream *stream = pIOHandler->Open(pFile, "rb");
     if (nullptr == stream) {
-        return;
+        throw DeadlyImportError("ASSBIN: Could not open ", pFile);
     }
 
     // signature
diff --git a/code/AssetLib/B3D/B3DImporter.cpp b/code/AssetLib/B3D/B3DImporter.cpp
index bcdb286be..3d9a5075a 100644
--- a/code/AssetLib/B3D/B3DImporter.cpp
+++ b/code/AssetLib/B3D/B3DImporter.cpp
@@ -145,7 +145,7 @@ AI_WONT_RETURN void B3DImporter::Oops() {
 // ------------------------------------------------------------------------------------------------
 AI_WONT_RETURN void B3DImporter::Fail(string str) {
 #ifdef DEBUG_B3D
-    ASSIMP_LOG_ERROR_F("Error in B3D file data: ", str);
+    ASSIMP_LOG_ERROR("Error in B3D file data: ", str);
 #endif
     throw DeadlyImportError("B3D Importer - error in B3D file data: ", str);
 }
@@ -233,7 +233,7 @@ string B3DImporter::ReadChunk() {
         tag += char(ReadByte());
     }
 #ifdef DEBUG_B3D
-    ASSIMP_LOG_DEBUG_F("ReadChunk: ", tag);
+    ASSIMP_LOG_DEBUG("ReadChunk: ", tag);
 #endif
     unsigned sz = (unsigned)ReadInt();
     _stack.push_back(_pos + sz);
@@ -397,7 +397,7 @@ void B3DImporter::ReadTRIS(int v0) {
         matid = 0;
     } else if (matid < 0 || matid >= (int)_materials.size()) {
 #ifdef DEBUG_B3D
-        ASSIMP_LOG_ERROR_F("material id=", matid);
+        ASSIMP_LOG_ERROR("material id=", matid);
 #endif
         Fail("Bad material id");
     }
@@ -417,7 +417,7 @@ void B3DImporter::ReadTRIS(int v0) {
         int i2 = ReadInt() + v0;
         if (i0 < 0 || i0 >= (int)_vertices.size() || i1 < 0 || i1 >= (int)_vertices.size() || i2 < 0 || i2 >= (int)_vertices.size()) {
 #ifdef DEBUG_B3D
-            ASSIMP_LOG_ERROR_F("Bad triangle index: i0=", i0, ", i1=", i1, ", i2=", i2);
+            ASSIMP_LOG_ERROR("Bad triangle index: i0=", i0, ", i1=", i1, ", i2=", i2);
 #endif
             Fail("Bad triangle index");
             continue;
diff --git a/code/AssetLib/BVH/BVHLoader.cpp b/code/AssetLib/BVH/BVHLoader.cpp
index 8ae99033c..cf78fb6c6 100644
--- a/code/AssetLib/BVH/BVHLoader.cpp
+++ b/code/AssetLib/BVH/BVHLoader.cpp
@@ -359,7 +359,7 @@ void BVHLoader::ReadMotion(aiScene * /*pScene*/) {
 std::string BVHLoader::GetNextToken() {
     // skip any preceding whitespace
     while (mReader != mBuffer.end()) {
-        if (!isspace(*mReader))
+        if (!isspace((unsigned char)*mReader))
             break;
 
         // count lines
@@ -372,7 +372,7 @@ std::string BVHLoader::GetNextToken() {
     // collect all chars till the next whitespace. BVH is easy in respect to that.
     std::string token;
     while (mReader != mBuffer.end()) {
-        if (isspace(*mReader))
+        if (isspace((unsigned char)*mReader))
             break;
 
         token.push_back(*mReader);
diff --git a/code/AssetLib/Blender/BlenderDNA.cpp b/code/AssetLib/Blender/BlenderDNA.cpp
index 4dcb3d654..3da0dce31 100644
--- a/code/AssetLib/Blender/BlenderDNA.cpp
+++ b/code/AssetLib/Blender/BlenderDNA.cpp
@@ -198,9 +198,9 @@ void DNAParser::Parse() {
         s.size = offset;
     }
 
-    ASSIMP_LOG_DEBUG_F("BlenderDNA: Got ", dna.structures.size(), " structures with totally ", fields, " fields");
+    ASSIMP_LOG_DEBUG("BlenderDNA: Got ", dna.structures.size(), " structures with totally ", fields, " fields");
 
-#ifdef ASSIMP_BUILD_BLENDER_DEBUG
+#if ASSIMP_BUILD_BLENDER_DEBUG_DNA
     dna.DumpToFile();
 #endif
 
@@ -208,7 +208,7 @@ void DNAParser::Parse() {
     dna.RegisterConverters();
 }
 
-#ifdef ASSIMP_BUILD_BLENDER_DEBUG
+#if ASSIMP_BUILD_BLENDER_DEBUG_DNA
 
 #include <fstream>
 // ------------------------------------------------------------------------------------------------
@@ -237,7 +237,7 @@ void DNA ::DumpToFile() {
 
     ASSIMP_LOG_INFO("BlenderDNA: Dumped dna to dna.txt");
 }
-#endif
+#endif // ASSIMP_BUILD_BLENDER_DEBUG_DNA
 
 // ------------------------------------------------------------------------------------------------
 /*static*/ void DNA ::ExtractArraySize(
diff --git a/code/AssetLib/Blender/BlenderDNA.h b/code/AssetLib/Blender/BlenderDNA.h
index 090d1be04..f566554b8 100644
--- a/code/AssetLib/Blender/BlenderDNA.h
+++ b/code/AssetLib/Blender/BlenderDNA.h
@@ -59,6 +59,13 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define ASSIMP_BUILD_BLENDER_DEBUG
 #endif
 
+// set this to non-zero to dump BlenderDNA stuff to dna.txt.
+// you could set it on the assimp build command line too without touching it here.
+// !!! please make sure this is set to 0 in the repo !!!
+#ifndef ASSIMP_BUILD_BLENDER_DEBUG_DNA
+#define ASSIMP_BUILD_BLENDER_DEBUG_DNA 0
+#endif
+
 // #define ASSIMP_BUILD_BLENDER_NO_STATS
 
 namespace Assimp {
@@ -495,7 +502,7 @@ public:
             const Structure &structure,
             const FileDatabase &db) const;
 
-#ifdef ASSIMP_BUILD_BLENDER_DEBUG
+#if ASSIMP_BUILD_BLENDER_DEBUG_DNA
     // --------------------------------------------------------
     /** Dump the DNA to a text file. This is for debugging purposes.
      *  The output file is `dna.txt` in the current working folder*/
diff --git a/code/AssetLib/Blender/BlenderDNA.inl b/code/AssetLib/Blender/BlenderDNA.inl
index aebcefa84..a46532057 100644
--- a/code/AssetLib/Blender/BlenderDNA.inl
+++ b/code/AssetLib/Blender/BlenderDNA.inl
@@ -565,7 +565,7 @@ template <> bool Structure :: ResolvePointer<std::shared_ptr,ElemBase>(std::shar
         // this might happen if DNA::RegisterConverters hasn't been called so far
         // or if the target type is not contained in `our` DNA.
         out.reset();
-        ASSIMP_LOG_WARN_F( "Failed to find a converter for the `",s.name,"` structure" );
+        ASSIMP_LOG_WARN( "Failed to find a converter for the `",s.name,"` structure" );
         return false;
     }
 
diff --git a/code/AssetLib/Blender/BlenderLoader.cpp b/code/AssetLib/Blender/BlenderLoader.cpp
index 71ab67721..7cf4e070e 100644
--- a/code/AssetLib/Blender/BlenderLoader.cpp
+++ b/code/AssetLib/Blender/BlenderLoader.cpp
@@ -132,12 +132,6 @@ bool BlenderImporter::CanRead(const std::string &pFile, IOSystem *pIOHandler, bo
     return false;
 }
 
-// ------------------------------------------------------------------------------------------------
-// List all extensions handled by this loader
-void BlenderImporter::GetExtensionList(std::set<std::string> &app) {
-    app.insert("blend");
-}
-
 // ------------------------------------------------------------------------------------------------
 // Loader registry entry
 const aiImporterDesc *BlenderImporter::GetInfo() const {
@@ -241,9 +235,9 @@ void BlenderImporter::InternReadFile(const std::string &pFile,
     stream->Read(magic, 3, 1);
     magic[3] = '\0';
 
-    LogInfo((format(), "Blender version is ", magic[0], ".", magic + 1,
+    LogInfo("Blender version is ", magic[0], ".", magic + 1,
             " (64bit: ", file.i64bit ? "true" : "false",
-            ", little endian: ", file.little ? "true" : "false", ")"));
+            ", little endian: ", file.little ? "true" : "false", ")");
 
     ParseBlendFile(file, stream);
 
@@ -316,7 +310,7 @@ void BlenderImporter::ExtractScene(Scene &out, const FileDatabase &file) {
     ss.Convert(out, file);
 
 #ifndef ASSIMP_BUILD_BLENDER_NO_STATS
-    ASSIMP_LOG_INFO_F(
+    ASSIMP_LOG_INFO(
             "(Stats) Fields read: ", file.stats().fields_read,
             ", pointers resolved: ", file.stats().pointers_resolved,
             ", cache hits: ", file.stats().cache_hits,
@@ -426,9 +420,9 @@ void BlenderImporter::ResolveImage(aiMaterial *out, const Material *mat, const M
             --s;
         }
 
-        curTex->achFormatHint[0] = s + 1 > e ? '\0' : (char)::tolower(s[1]);
-        curTex->achFormatHint[1] = s + 2 > e ? '\0' : (char)::tolower(s[2]);
-        curTex->achFormatHint[2] = s + 3 > e ? '\0' : (char)::tolower(s[3]);
+        curTex->achFormatHint[0] = s + 1 > e ? '\0' : (char)::tolower((unsigned char)s[1]);
+        curTex->achFormatHint[1] = s + 2 > e ? '\0' : (char)::tolower((unsigned char)s[2]);
+        curTex->achFormatHint[2] = s + 3 > e ? '\0' : (char)::tolower((unsigned char)s[3]);
         curTex->achFormatHint[3] = '\0';
 
         // tex->mHeight = 0;
@@ -440,7 +434,7 @@ void BlenderImporter::ResolveImage(aiMaterial *out, const Material *mat, const M
 
         curTex->pcData = reinterpret_cast<aiTexel *>(ch);
 
-        LogInfo("Reading embedded texture, original file was " + std::string(img->name));
+        LogInfo("Reading embedded texture, original file was ", img->name);
     } else {
         name = aiString(img->name);
     }
@@ -522,7 +516,7 @@ void BlenderImporter::ResolveTexture(aiMaterial *out, const Material *mat, const
     case Tex::Type_POINTDENSITY:
     case Tex::Type_VOXELDATA:
 
-        LogWarn(std::string("Encountered a texture with an unsupported type: ") + dispnam);
+        LogWarn("Encountered a texture with an unsupported type: ", dispnam);
         AddSentinelTexture(out, mat, tex, conv_data);
         break;
 
@@ -758,7 +752,7 @@ void BlenderImporter::CheckActualType(const ElemBase *dt, const char *check) {
 
 // ------------------------------------------------------------------------------------------------
 void BlenderImporter::NotSupportedObjectType(const Object *obj, const char *type) {
-    LogWarn((format(), "Object `", obj->id.name, "` - type is unsupported: `", type, "`, skipping"));
+    LogWarn("Object `", obj->id.name, "` - type is unsupported: `", type, "`, skipping");
 }
 
 // ------------------------------------------------------------------------------------------------
diff --git a/code/AssetLib/Blender/BlenderLoader.h b/code/AssetLib/Blender/BlenderLoader.h
index fdbb586c9..42da76514 100644
--- a/code/AssetLib/Blender/BlenderLoader.h
+++ b/code/AssetLib/Blender/BlenderLoader.h
@@ -110,7 +110,6 @@ public:
 
 protected:
     const aiImporterDesc* GetInfo () const;
-    void GetExtensionList(std::set<std::string>& app);
     void SetupProperties(const Importer* pImp);
     void InternReadFile( const std::string& pFile, aiScene* pScene, IOSystem* pIOHandler);
     void ParseBlendFile(Blender::FileDatabase& out, std::shared_ptr<IOStream> stream);
diff --git a/code/AssetLib/Blender/BlenderModifier.cpp b/code/AssetLib/Blender/BlenderModifier.cpp
index 995e20b1c..bc5c8c2d9 100644
--- a/code/AssetLib/Blender/BlenderModifier.cpp
+++ b/code/AssetLib/Blender/BlenderModifier.cpp
@@ -90,7 +90,7 @@ void BlenderModifierShowcase::ApplyModifiers(aiNode &out, ConversionData &conv_d
 
         const Structure *s = conv_data.db.dna.Get(cur->dna_type);
         if (!s) {
-            ASSIMP_LOG_WARN_F("BlendModifier: could not resolve DNA name: ", cur->dna_type);
+            ASSIMP_LOG_WARN("BlendModifier: could not resolve DNA name: ", cur->dna_type);
             continue;
         }
 
@@ -132,7 +132,7 @@ void BlenderModifierShowcase::ApplyModifiers(aiNode &out, ConversionData &conv_d
             }
         }
         if (curgod) {
-            ASSIMP_LOG_WARN_F("Couldn't find a handler for modifier: ", dat.name);
+            ASSIMP_LOG_WARN("Couldn't find a handler for modifier: ", dat.name);
         }
     }
 
@@ -140,7 +140,7 @@ void BlenderModifierShowcase::ApplyModifiers(aiNode &out, ConversionData &conv_d
     // object, we still can't say whether our modifier implementations were
     // able to fully do their job.
     if (ful) {
-        ASSIMP_LOG_DEBUG_F("BlendModifier: found handlers for ", cnt, " of ", ful, " modifiers on `", orig_object.id.name,
+        ASSIMP_LOG_DEBUG("BlendModifier: found handlers for ", cnt, " of ", ful, " modifiers on `", orig_object.id.name,
                 "`, check log messages above for errors");
     }
 }
@@ -248,7 +248,7 @@ void BlenderModifier_Mirror ::DoIt(aiNode &out, ConversionData &conv_data, const
     out.mMeshes = nind;
     out.mNumMeshes *= 2;
 
-    ASSIMP_LOG_INFO_F("BlendModifier: Applied the `Mirror` modifier to `",
+    ASSIMP_LOG_INFO("BlendModifier: Applied the `Mirror` modifier to `",
             orig_object.id.name, "`");
 }
 
@@ -277,7 +277,7 @@ void BlenderModifier_Subdivision ::DoIt(aiNode &out, ConversionData &conv_data,
         break;
 
     default:
-        ASSIMP_LOG_WARN_F("BlendModifier: Unrecognized subdivision algorithm: ", mir.subdivType);
+        ASSIMP_LOG_WARN("BlendModifier: Unrecognized subdivision algorithm: ", mir.subdivType);
         return;
     };
 
@@ -292,7 +292,7 @@ void BlenderModifier_Subdivision ::DoIt(aiNode &out, ConversionData &conv_data,
     subd->Subdivide(meshes, out.mNumMeshes, tempmeshes.get(), std::max(mir.renderLevels, mir.levels), true);
     std::copy(tempmeshes.get(), tempmeshes.get() + out.mNumMeshes, meshes);
 
-    ASSIMP_LOG_INFO_F("BlendModifier: Applied the `Subdivision` modifier to `",
+    ASSIMP_LOG_INFO("BlendModifier: Applied the `Subdivision` modifier to `",
             orig_object.id.name, "`");
 }
 
diff --git a/code/AssetLib/Blender/BlenderModifier.h b/code/AssetLib/Blender/BlenderModifier.h
index 7d4096cde..daf120087 100644
--- a/code/AssetLib/Blender/BlenderModifier.h
+++ b/code/AssetLib/Blender/BlenderModifier.h
@@ -86,7 +86,7 @@ public:
         const Scene& /*in*/,
         const Object& /*orig_object*/
     ) {
-        ASSIMP_LOG_INFO_F("This modifier is not supported, skipping: ",orig_modifier.dna_type );
+        ASSIMP_LOG_INFO("This modifier is not supported, skipping: ",orig_modifier.dna_type );
         return;
     }
 };
diff --git a/code/AssetLib/C4D/C4DImporter.cpp b/code/AssetLib/C4D/C4DImporter.cpp
index 24fd6f622..434d1429e 100644
--- a/code/AssetLib/C4D/C4DImporter.cpp
+++ b/code/AssetLib/C4D/C4DImporter.cpp
@@ -2,7 +2,7 @@
 Open Asset Import Library (assimp)
 ----------------------------------------------------------------------
 
-Copyright (c) 2006-2020, assimp team
+Copyright (c) 2006-2021, assimp team
 All rights reserved.
 
 Redistribution and use of this software in source and binary forms,
@@ -51,7 +51,6 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #endif
 
 #include "C4DImporter.h"
-#include <assimp/TinyFormatter.h>
 #include <memory>
 #include <assimp/IOSystem.hpp>
 #include <assimp/scene.h>
@@ -65,7 +64,19 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "c4d_file.h"
 #include "default_alien_overloads.h"
 
-using namespace melange;
+namespace {
+
+aiString aiStringFrom(cineware::String const & cinestring) {
+    aiString result;
+    cinestring.GetCString(result.data, MAXLEN-1);
+    result.length = static_cast<ai_uint32>(cinestring.GetLength());
+    return result;
+}
+
+}
+
+using namespace Assimp;
+using namespace cineware;
 
 // overload this function and fill in your own unique data
 void GetWriterInfo(int &id, String &appname) {
@@ -73,9 +84,6 @@ void GetWriterInfo(int &id, String &appname) {
     appname = "Open Asset Import Library";
 }
 
-using namespace Assimp;
-using namespace Assimp::Formatter;
-
 namespace Assimp {
     template<> const char* LogFunctions<C4DImporter>::Prefix() {
         static auto prefix = "C4D: ";
@@ -97,17 +105,6 @@ static const aiImporterDesc desc = {
 };
 
 
-// ------------------------------------------------------------------------------------------------
-C4DImporter::C4DImporter()
-: BaseImporter() {
-    // empty
-}
-
-// ------------------------------------------------------------------------------------------------
-C4DImporter::~C4DImporter() {
-    // empty
-}
-
 // ------------------------------------------------------------------------------------------------
 bool C4DImporter::CanRead( const std::string& pFile, IOSystem* pIOHandler, bool checkSig) const {
     const std::string& extension = GetExtension(pFile);
@@ -125,11 +122,6 @@ const aiImporterDesc* C4DImporter::GetInfo () const {
     return &desc;
 }
 
-// ------------------------------------------------------------------------------------------------
-void C4DImporter::SetupProperties(const Importer* /*pImp*/) {
-    // nothing to be done for the moment
-}
-
 
 // ------------------------------------------------------------------------------------------------
 // Imports the given file into the given scene structure.
@@ -199,8 +191,8 @@ void C4DImporter::InternReadFile( const std::string& pFile, aiScene* pScene, IOS
 
 
 // ------------------------------------------------------------------------------------------------
-bool C4DImporter::ReadShader(aiMaterial* out, melange::BaseShader* shader) {
-    // based on Melange sample code (C4DImportExport.cpp)
+bool C4DImporter::ReadShader(aiMaterial* out, BaseShader* shader) {
+    // based on Cineware sample code (C4DImportExport.cpp)
     while(shader) {
         if(shader->GetType() == Xlayer) {
             BaseContainer* container = shader->GetDataInstance();
@@ -242,13 +234,11 @@ bool C4DImporter::ReadShader(aiMaterial* out, melange::BaseShader* shader) {
                 lsl = lsl->GetNext();
             }
         } else if ( shader->GetType() == Xbitmap ) {
-            aiString path;
-            shader->GetFileName().GetString().GetCString(path.data, MAXLEN-1);
-            path.length = ::strlen(path.data);
+            auto const path = aiStringFrom(shader->GetFileName().GetString());
             out->AddProperty(&path, AI_MATKEY_TEXTURE_DIFFUSE(0));
             return true;
         } else {
-            LogWarn("ignoring shader type: " + std::string(GetObjectTypeName(shader->GetType())));
+            LogWarn("ignoring shader type: ", GetObjectTypeName(shader->GetType()));
         }
         shader = shader->GetNext();
     }
@@ -257,18 +247,15 @@ bool C4DImporter::ReadShader(aiMaterial* out, melange::BaseShader* shader) {
 }
 
 // ------------------------------------------------------------------------------------------------
-void C4DImporter::ReadMaterials(melange::BaseMaterial* mat) {
-    // based on Melange sample code
+void C4DImporter::ReadMaterials(BaseMaterial* mat) {
+    // based on Cineware sample code
     while (mat) {
-        const String& name = mat->GetName();
         if (mat->GetType() == Mmaterial) {
             aiMaterial* out = new aiMaterial();
             material_mapping[mat] = static_cast<unsigned int>(materials.size());
             materials.push_back(out);
 
-            aiString ai_name;
-            name.GetCString(ai_name.data, MAXLEN-1);
-            ai_name.length = ::strlen(ai_name.data);
+            auto const ai_name = aiStringFrom(mat->GetName());
             out->AddProperty(&ai_name, AI_MATKEY_NAME);
 
             Material& m = dynamic_cast<Material&>(*mat);
@@ -294,7 +281,7 @@ void C4DImporter::ReadMaterials(melange::BaseMaterial* mat) {
                 ReadShader(out, shader);
             }
         } else {
-            LogWarn("ignoring plugin material: " + std::string(GetObjectTypeName(mat->GetType())));
+            LogWarn("ignoring plugin material: ", GetObjectTypeName(mat->GetType()));
         }
         mat = mat->GetNext();
     }
@@ -305,19 +292,15 @@ void C4DImporter::RecurseHierarchy(BaseObject* object, aiNode* parent) {
     ai_assert(parent != nullptr );
     std::vector<aiNode*> nodes;
 
-    // based on Melange sample code
+    // based on Cineware sample code
     while (object) {
-        const String& name = object->GetName();
         const LONG type = object->GetType();
         const Matrix& ml = object->GetMl();
 
-        aiString string;
-        name.GetCString(string.data, MAXLEN-1);
-        string.length = ::strlen(string.data);
         aiNode* const nd = new aiNode();
 
         nd->mParent = parent;
-        nd->mName = string;
+        nd->mName = aiStringFrom(object->GetName());
 
         nd->mTransformation.a1 = ml.v1.x;
         nd->mTransformation.b1 = ml.v1.y;
@@ -352,7 +335,7 @@ void C4DImporter::RecurseHierarchy(BaseObject* object, aiNode* parent) {
                 meshes.push_back(mesh);
             }
         } else {
-            LogWarn("ignoring object: " + std::string(GetObjectTypeName(type)));
+            LogWarn("ignoring object: ", GetObjectTypeName(type));
         }
 
         RecurseHierarchy(object->GetDown(), nd);
@@ -370,7 +353,7 @@ aiMesh* C4DImporter::ReadMesh(BaseObject* object) {
     ai_assert(object != nullptr);
     ai_assert( object->GetType() == Opolygon );
 
-    // based on Melange sample code
+    // based on Cineware sample code
     PolygonObject* const polyObject = dynamic_cast<PolygonObject*>(object);
     ai_assert(polyObject != nullptr);
 
@@ -618,4 +601,3 @@ unsigned int C4DImporter::ResolveMaterial(PolygonObject* obj) {
 }
 
 #endif // ASSIMP_BUILD_NO_C4D_IMPORTER
-
diff --git a/code/AssetLib/C4D/C4DImporter.h b/code/AssetLib/C4D/C4DImporter.h
index f9406c3e0..c44cf5e37 100644
--- a/code/AssetLib/C4D/C4DImporter.h
+++ b/code/AssetLib/C4D/C4DImporter.h
@@ -2,7 +2,7 @@
 Open Asset Import Library (assimp)
 ----------------------------------------------------------------------
 
-Copyright (c) 2006-2020, assimp team
+Copyright (c) 2006-2021, assimp team
 All rights reserved.
 
 Redistribution and use of this software in source and binary forms,
@@ -56,8 +56,8 @@ struct aiMaterial;
 
 struct aiImporterDesc;
 
-namespace melange {
-    class BaseObject; // c4d_file.h
+namespace cineware {
+    class BaseObject;
     class PolygonObject;
     class BaseMaterial;
     class BaseShader;
@@ -71,43 +71,34 @@ namespace Assimp  {
     }
 
 // -------------------------------------------------------------------------------------------
-/** Importer class to load Cinema4D files using the Melange library to be obtained from
- *  www.plugincafe.com
+/** Importer class to load Cinema4D files using the Cineware library to be obtained from
+ *  https://developers.maxon.net
  *
- *  Note that Melange is not free software. */
+ *  Note that Cineware is not free software. */
 // -------------------------------------------------------------------------------------------
 class C4DImporter : public BaseImporter, public LogFunctions<C4DImporter> {
 public:
-    C4DImporter();
-    ~C4DImporter();
-    bool CanRead( const std::string& pFile, IOSystem* pIOHandler,
-        bool checkSig) const;
+    bool CanRead( const std::string& pFile, IOSystem*, bool checkSig) const override;
 
 protected:
 
-    // --------------------
-    const aiImporterDesc* GetInfo () const;
+    const aiImporterDesc* GetInfo () const override;
 
-    // --------------------
-    void SetupProperties(const Importer* pImp);
-
-    // --------------------
-    void InternReadFile( const std::string& pFile, aiScene* pScene,
-        IOSystem* pIOHandler);
+    void InternReadFile( const std::string& pFile, aiScene*, IOSystem* ) override;
 
 private:
 
-    void ReadMaterials(melange::BaseMaterial* mat);
-    void RecurseHierarchy(melange::BaseObject* object, aiNode* parent);
-    aiMesh* ReadMesh(melange::BaseObject* object);
-    unsigned int ResolveMaterial(melange::PolygonObject* obj);
+    void ReadMaterials(cineware::BaseMaterial* mat);
+    void RecurseHierarchy(cineware::BaseObject* object, aiNode* parent);
+    aiMesh* ReadMesh(cineware::BaseObject* object);
+    unsigned int ResolveMaterial(cineware::PolygonObject* obj);
 
-    bool ReadShader(aiMaterial* out, melange::BaseShader* shader);
+    bool ReadShader(aiMaterial* out, cineware::BaseShader* shader);
 
     std::vector<aiMesh*> meshes;
     std::vector<aiMaterial*> materials;
 
-    typedef std::map<melange::BaseMaterial*, unsigned int> MaterialMap;
+    typedef std::map<cineware::BaseMaterial*, unsigned int> MaterialMap;
     MaterialMap material_mapping;
 
 }; // !class C4DImporter
diff --git a/code/AssetLib/COB/COBLoader.cpp b/code/AssetLib/COB/COBLoader.cpp
index efe7fc446..94327c683 100644
--- a/code/AssetLib/COB/COBLoader.cpp
+++ b/code/AssetLib/COB/COBLoader.cpp
@@ -137,7 +137,13 @@ void COBImporter::SetupProperties(const Importer * /*pImp*/) {
 // Imports the given file into the given scene structure.
 void COBImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) {
     COB::Scene scene;
-    std::unique_ptr<StreamReaderLE> stream(new StreamReaderLE(pIOHandler->Open(pFile, "rb")));
+
+    auto file = pIOHandler->Open(pFile, "rb");
+    if (!file) {
+        ThrowException("Could not open " + pFile);
+    }
+
+    std::unique_ptr<StreamReaderLE> stream(new StreamReaderLE(file));
 
     // check header
     char head[32];
@@ -146,7 +152,7 @@ void COBImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
         ThrowException("Could not found magic id: `Caligari`");
     }
 
-    ASSIMP_LOG_INFO_F("File format tag: ", std::string(head + 9, 6));
+    ASSIMP_LOG_INFO("File format tag: ", std::string(head + 9, 6));
     if (head[16] != 'L') {
         ThrowException("File is big-endian, which is not supported");
     }
@@ -295,8 +301,7 @@ aiNode *COBImporter::BuildNodes(const Node &root, const Scene &scin, aiScene *fi
                     }
                     std::unique_ptr<const Material> defmat;
                     if (!min) {
-                        ASSIMP_LOG_VERBOSE_DEBUG(format() << "Could not resolve material index "
-                                                  << reflist.first << " - creating default material for this slot");
+                        ASSIMP_LOG_VERBOSE_DEBUG("Could not resolve material index ", reflist.first, " - creating default material for this slot");
 
                         defmat.reset(min = new Material());
                     }
@@ -521,7 +526,7 @@ void COBImporter::ReadMat1_Ascii(Scene &out, LineSplitter &splitter, const Chunk
 
     ++splitter;
     if (!splitter.match_start("mat# ")) {
-        ASSIMP_LOG_WARN_F("Expected `mat#` line in `Mat1` chunk ", nfo.id);
+        ASSIMP_LOG_WARN("Expected `mat#` line in `Mat1` chunk ", nfo.id);
         return;
     }
 
@@ -533,7 +538,7 @@ void COBImporter::ReadMat1_Ascii(Scene &out, LineSplitter &splitter, const Chunk
     ++splitter;
 
     if (!splitter.match_start("shader: ")) {
-        ASSIMP_LOG_WARN_F("Expected `mat#` line in `Mat1` chunk ", nfo.id);
+        ASSIMP_LOG_WARN("Expected `mat#` line in `Mat1` chunk ", nfo.id);
         return;
     }
     std::string shader = std::string(splitter[1]);
@@ -544,12 +549,12 @@ void COBImporter::ReadMat1_Ascii(Scene &out, LineSplitter &splitter, const Chunk
     } else if (shader == "phong") {
         mat.shader = Material::PHONG;
     } else if (shader != "flat") {
-        ASSIMP_LOG_WARN_F("Unknown value for `shader` in `Mat1` chunk ", nfo.id);
+        ASSIMP_LOG_WARN("Unknown value for `shader` in `Mat1` chunk ", nfo.id);
     }
 
     ++splitter;
     if (!splitter.match_start("rgb ")) {
-        ASSIMP_LOG_WARN_F("Expected `rgb` line in `Mat1` chunk ", nfo.id);
+        ASSIMP_LOG_WARN("Expected `rgb` line in `Mat1` chunk ", nfo.id);
     }
 
     const char *rgb = splitter[1];
@@ -557,7 +562,7 @@ void COBImporter::ReadMat1_Ascii(Scene &out, LineSplitter &splitter, const Chunk
 
     ++splitter;
     if (!splitter.match_start("alpha ")) {
-        ASSIMP_LOG_WARN_F("Expected `alpha` line in `Mat1` chunk ", nfo.id);
+        ASSIMP_LOG_WARN("Expected `alpha` line in `Mat1` chunk ", nfo.id);
     }
 
     const char *tokens[10];
@@ -577,7 +582,7 @@ void COBImporter::ReadUnit_Ascii(Scene &out, LineSplitter &splitter, const Chunk
     }
     ++splitter;
     if (!splitter.match_start("Units ")) {
-        ASSIMP_LOG_WARN_F("Expected `Units` line in `Unit` chunk ", nfo.id);
+        ASSIMP_LOG_WARN("Expected `Units` line in `Unit` chunk ", nfo.id);
         return;
     }
 
@@ -588,12 +593,12 @@ void COBImporter::ReadUnit_Ascii(Scene &out, LineSplitter &splitter, const Chunk
             const unsigned int t = strtoul10(splitter[1]);
 
             nd->unit_scale = t >= sizeof(units) / sizeof(units[0]) ? (
-                                                                             ASSIMP_LOG_WARN_F(t, " is not a valid value for `Units` attribute in `Unit chunk` ", nfo.id), 1.f) :
+                                                                             ASSIMP_LOG_WARN(t, " is not a valid value for `Units` attribute in `Unit chunk` ", nfo.id), 1.f) :
                                                                      units[t];
             return;
         }
     }
-    ASSIMP_LOG_WARN_F("`Unit` chunk ", nfo.id, " is a child of ", nfo.parent_id, " which does not exist");
+    ASSIMP_LOG_WARN("`Unit` chunk ", nfo.id, " is a child of ", nfo.parent_id, " which does not exist");
 }
 
 // ------------------------------------------------------------------------------------------------
@@ -622,13 +627,13 @@ void COBImporter::ReadLght_Ascii(Scene &out, LineSplitter &splitter, const Chunk
     } else if (splitter.match_start("Spot ")) {
         msh.ltype = Light::SPOT;
     } else {
-        ASSIMP_LOG_WARN_F("Unknown kind of light source in `Lght` chunk ", nfo.id, " : ", *splitter);
+        ASSIMP_LOG_WARN("Unknown kind of light source in `Lght` chunk ", nfo.id, " : ", *splitter);
         msh.ltype = Light::SPOT;
     }
 
     ++splitter;
     if (!splitter.match_start("color ")) {
-        ASSIMP_LOG_WARN_F("Expected `color` line in `Lght` chunk ", nfo.id);
+        ASSIMP_LOG_WARN("Expected `color` line in `Lght` chunk ", nfo.id);
     }
 
     const char *rgb = splitter[1];
@@ -636,14 +641,14 @@ void COBImporter::ReadLght_Ascii(Scene &out, LineSplitter &splitter, const Chunk
 
     SkipSpaces(&rgb);
     if (strncmp(rgb, "cone angle", 10) != 0) {
-        ASSIMP_LOG_WARN_F("Expected `cone angle` entity in `color` line in `Lght` chunk ", nfo.id);
+        ASSIMP_LOG_WARN("Expected `cone angle` entity in `color` line in `Lght` chunk ", nfo.id);
     }
     SkipSpaces(rgb + 10, &rgb);
     msh.angle = fast_atof(&rgb);
 
     SkipSpaces(&rgb);
     if (strncmp(rgb, "inner angle", 11) != 0) {
-        ASSIMP_LOG_WARN_F("Expected `inner angle` entity in `color` line in `Lght` chunk ", nfo.id);
+        ASSIMP_LOG_WARN("Expected `inner angle` entity in `color` line in `Lght` chunk ", nfo.id);
     }
     SkipSpaces(rgb + 11, &rgb);
     msh.inner_angle = fast_atof(&rgb);
@@ -1027,7 +1032,7 @@ void COBImporter::ReadMat1_Binary(COB::Scene &out, StreamReaderLE &reader, const
         mat.type = Material::METAL;
         break;
     default:
-        ASSIMP_LOG_ERROR_F("Unrecognized shader type in `Mat1` chunk with id ", nfo.id);
+        ASSIMP_LOG_ERROR("Unrecognized shader type in `Mat1` chunk with id ", nfo.id);
         mat.type = Material::FLAT;
     }
 
@@ -1042,7 +1047,7 @@ void COBImporter::ReadMat1_Binary(COB::Scene &out, StreamReaderLE &reader, const
         mat.autofacet = Material::SMOOTH;
         break;
     default:
-        ASSIMP_LOG_ERROR_F("Unrecognized faceting mode in `Mat1` chunk with id ", nfo.id);
+        ASSIMP_LOG_ERROR("Unrecognized faceting mode in `Mat1` chunk with id ", nfo.id);
         mat.autofacet = Material::FACETED;
     }
     mat.autofacet_angle = static_cast<float>(reader.GetI1());
@@ -1170,13 +1175,13 @@ void COBImporter::ReadUnit_Binary(COB::Scene &out, StreamReaderLE &reader, const
         if (nd->id == nfo.parent_id) {
             const unsigned int t = reader.GetI2();
             nd->unit_scale = t >= sizeof(units) / sizeof(units[0]) ? (
-                                                                             ASSIMP_LOG_WARN_F(t, " is not a valid value for `Units` attribute in `Unit chunk` ", nfo.id), 1.f) :
+                                                                             ASSIMP_LOG_WARN(t, " is not a valid value for `Units` attribute in `Unit chunk` ", nfo.id), 1.f) :
                                                                      units[t];
 
             return;
         }
     }
-    ASSIMP_LOG_WARN_F("`Unit` chunk ", nfo.id, " is a child of ", nfo.parent_id, " which does not exist");
+    ASSIMP_LOG_WARN("`Unit` chunk ", nfo.id, " is a child of ", nfo.parent_id, " which does not exist");
 }
 
 #endif // ASSIMP_BUILD_NO_COB_IMPORTER
diff --git a/code/AssetLib/Collada/ColladaLoader.cpp b/code/AssetLib/Collada/ColladaLoader.cpp
index 902eebc4b..492e6971f 100644
--- a/code/AssetLib/Collada/ColladaLoader.cpp
+++ b/code/AssetLib/Collada/ColladaLoader.cpp
@@ -75,7 +75,7 @@ static const aiImporterDesc desc = {
     3,
     1,
     5,
-    "dae zae"
+    "dae xml zae"
 };
 
 static const float kMillisecondsFromSeconds = 1000.f;
@@ -317,7 +317,7 @@ void ColladaLoader::ResolveNodeInstances(const ColladaParser &pParser, const Nod
             nd = FindNode(pParser.mRootNode, nodeInst.mNode);
         }
         if (nullptr == nd) {
-            ASSIMP_LOG_ERROR_F("Collada: Unable to resolve reference to instanced node ", nodeInst.mNode);
+            ASSIMP_LOG_ERROR("Collada: Unable to resolve reference to instanced node ", nodeInst.mNode);
         } else {
             //  attach this node to the list of children
             resolved.push_back(nd);
@@ -347,7 +347,7 @@ void ColladaLoader::BuildLightsForNode(const ColladaParser &pParser, const Node
         // find the referred light
         ColladaParser::LightLibrary::const_iterator srcLightIt = pParser.mLightLibrary.find(lid.mLight);
         if (srcLightIt == pParser.mLightLibrary.end()) {
-            ASSIMP_LOG_WARN_F("Collada: Unable to find light for ID \"", lid.mLight, "\". Skipping.");
+            ASSIMP_LOG_WARN("Collada: Unable to find light for ID \"", lid.mLight, "\". Skipping.");
             continue;
         }
         const Collada::Light *srcLight = &srcLightIt->second;
@@ -412,7 +412,7 @@ void ColladaLoader::BuildCamerasForNode(const ColladaParser &pParser, const Node
         // find the referred light
         ColladaParser::CameraLibrary::const_iterator srcCameraIt = pParser.mCameraLibrary.find(cid.mCamera);
         if (srcCameraIt == pParser.mCameraLibrary.end()) {
-            ASSIMP_LOG_WARN_F("Collada: Unable to find camera for ID \"", cid.mCamera, "\". Skipping.");
+            ASSIMP_LOG_WARN("Collada: Unable to find camera for ID \"", cid.mCamera, "\". Skipping.");
             continue;
         }
         const Collada::Camera *srcCamera = &srcCameraIt->second;
@@ -486,7 +486,7 @@ void ColladaLoader::BuildMeshesForNode(const ColladaParser &pParser, const Node
             }
 
             if (nullptr == srcMesh) {
-                ASSIMP_LOG_WARN_F("Collada: Unable to find geometry for ID \"", mid.mMeshOrController, "\". Skipping.");
+                ASSIMP_LOG_WARN("Collada: Unable to find geometry for ID \"", mid.mMeshOrController, "\". Skipping.");
                 continue;
             }
         } else {
@@ -511,7 +511,7 @@ void ColladaLoader::BuildMeshesForNode(const ColladaParser &pParser, const Node
                 table = &meshMatIt->second;
                 meshMaterial = table->mMatName;
             } else {
-                ASSIMP_LOG_WARN_F("Collada: No material specified for subgroup <", submesh.mMaterial, "> in geometry <",
+                ASSIMP_LOG_WARN("Collada: No material specified for subgroup <", submesh.mMaterial, "> in geometry <",
                         mid.mMeshOrController, ">.");
                 if (!mid.mMaterials.empty()) {
                     meshMaterial = mid.mMaterials.begin()->second.mMatName;
@@ -883,7 +883,7 @@ aiMesh *ColladaLoader::CreateMesh(const ColladaParser &pParser, const Mesh *pSrc
             if (nullptr != bnode) {
                 bone->mName.Set(FindNameForNode(bnode));
             } else {
-                ASSIMP_LOG_WARN_F("ColladaLoader::CreateMesh(): could not find corresponding node for joint \"", bone->mName.data, "\".");
+                ASSIMP_LOG_WARN("ColladaLoader::CreateMesh(): could not find corresponding node for joint \"", bone->mName.data, "\".");
             }
 
             // and insert bone
@@ -1184,7 +1184,7 @@ void ColladaLoader::CreateAnimation(aiScene *pScene, const ColladaParser &pParse
                 else if (subElement == "Z")
                     entry.mSubElement = 2;
                 else
-                    ASSIMP_LOG_WARN_F("Unknown anim subelement <", subElement, ">. Ignoring");
+                    ASSIMP_LOG_WARN("Unknown anim subelement <", subElement, ">. Ignoring");
             } else {
                 // no sub-element following, transformId is remaining string
                 entry.mTransformId = srcChannel.mTarget.substr(slashPos + 1);
@@ -1241,7 +1241,7 @@ void ColladaLoader::CreateAnimation(aiScene *pScene, const ColladaParser &pParse
                     continue;
                 }
                 entry.mTargetId = entry.mTransformId;
-                entry.mTransformId = "";
+                entry.mTransformId = std::string();
             }
 
             entry.mChannel = &(*cit);
@@ -1711,7 +1711,7 @@ aiString ColladaLoader::FindFilenameForEffectTexture(const ColladaParser &pParse
     // find the image referred by this name in the image library of the scene
     ColladaParser::ImageLibrary::const_iterator imIt = pParser.mImageLibrary.find(name);
     if (imIt == pParser.mImageLibrary.end()) {
-        ASSIMP_LOG_WARN_F("Collada: Unable to resolve effect texture entry \"", pName, "\", ended up at ID \"", name, "\".");
+        ASSIMP_LOG_WARN("Collada: Unable to resolve effect texture entry \"", pName, "\", ended up at ID \"", name, "\".");
 
         //set default texture file name
         result.Set(name + ".jpg");
diff --git a/code/AssetLib/Collada/ColladaParser.cpp b/code/AssetLib/Collada/ColladaParser.cpp
index 42166fdd4..5dbf0a567 100644
--- a/code/AssetLib/Collada/ColladaParser.cpp
+++ b/code/AssetLib/Collada/ColladaParser.cpp
@@ -71,7 +71,7 @@ static void ReportWarning(const char *msg, ...) {
     ai_assert(iLen > 0);
 
     va_end(args);
-    ASSIMP_LOG_WARN_F("Validation warning: ", std::string(szBuffer, iLen));
+    ASSIMP_LOG_WARN("Validation warning: ", std::string(szBuffer, iLen));
 }
 
 static bool FindCommonKey(const std::string &collada_key, const MetaKeyPairVector &key_renaming, size_t &found_index) {
@@ -234,7 +234,7 @@ void ColladaParser::UriDecodePath(aiString &ss) {
 #if defined(_MSC_VER)
     if (ss.data[0] == '/' && isalpha((unsigned char)ss.data[1]) && ss.data[2] == ':') {
 #else
-    if (ss.data[0] == '/' && isalpha(ss.data[1]) && ss.data[2] == ':') {
+    if (ss.data[0] == '/' && isalpha((unsigned char)ss.data[1]) && ss.data[2] == ':') {
 #endif
         --ss.length;
         ::memmove(ss.data, ss.data + 1, ss.length);
@@ -623,8 +623,7 @@ void ColladaParser::ReadController(XmlNode &node, Collada::Controller &controlle
     controller.mType = Skin;
     controller.mMethod = Normalized;
 
-    XmlNodeIterator xmlIt(node);
-    xmlIt.collectChildrenPreOrder(node);
+    XmlNodeIterator xmlIt(node, XmlNodeIterator::PreOrderMode);
     XmlNode currentNode;
     while (xmlIt.getNext(currentNode)) {
 
@@ -929,8 +928,7 @@ void ColladaParser::ReadMaterial(XmlNode &node, Collada::Material &pMaterial) {
 // ------------------------------------------------------------------------------------------------
 // Reads a light entry into the given light
 void ColladaParser::ReadLight(XmlNode &node, Collada::Light &pLight) {
-    XmlNodeIterator xmlIt(node);
-    xmlIt.collectChildrenPreOrder(node);
+    XmlNodeIterator xmlIt(node, XmlNodeIterator::PreOrderMode);
     XmlNode currentNode;
     while (xmlIt.getNext(currentNode)) {
         const std::string &currentName = currentNode.name();
@@ -991,10 +989,8 @@ void ColladaParser::ReadLight(XmlNode &node, Collada::Light &pLight) {
 // ------------------------------------------------------------------------------------------------
 // Reads a camera entry into the given light
 void ColladaParser::ReadCamera(XmlNode &node, Collada::Camera &camera) {
-    XmlNodeIterator xmlIt(node);
-    xmlIt.collectChildrenPreOrder(node);
+    XmlNodeIterator xmlIt(node, XmlNodeIterator::PreOrderMode);
     XmlNode currentNode;
-
     while (xmlIt.getNext(currentNode)) {
         const std::string &currentName = currentNode.name();
         if (currentName == "orthographic") {
@@ -1050,11 +1046,10 @@ void ColladaParser::ReadEffect(XmlNode &node, Collada::Effect &pEffect) {
 // ------------------------------------------------------------------------------------------------
 // Reads an COMMON effect profile
 void ColladaParser::ReadEffectProfileCommon(XmlNode &node, Collada::Effect &pEffect) {
-    XmlNodeIterator xmlIt(node);
-    xmlIt.collectChildrenPreOrder(node);
+    XmlNodeIterator xmlIt(node, XmlNodeIterator::PreOrderMode);
     XmlNode currentNode;
     while (xmlIt.getNext(currentNode)) {
-        const std::string &currentName = currentNode.name();
+        const std::string currentName = currentNode.name();
         if (currentName == "newparam") {
             // save ID
             std::string sid = currentNode.attribute("sid").as_string();
@@ -1145,10 +1140,9 @@ void ColladaParser::ReadSamplerProperties(XmlNode &node, Sampler &out) {
     if (node.empty()) {
         return;
     }
-    XmlNodeIterator xmlIt(node);
-    xmlIt.collectChildrenPreOrder(node);
-    XmlNode currentNode;
 
+    XmlNodeIterator xmlIt(node, XmlNodeIterator::PreOrderMode);
+    XmlNode currentNode;
     while (xmlIt.getNext(currentNode)) {
         const std::string &currentName = currentNode.name();
         // MAYA extensions
@@ -1208,10 +1202,9 @@ void ColladaParser::ReadEffectColor(XmlNode &node, aiColor4D &pColor, Sampler &p
     if (node.empty()) {
         return;
     }
-    XmlNodeIterator xmlIt(node);
-    xmlIt.collectChildrenPreOrder(node);
-    XmlNode currentNode;
 
+    XmlNodeIterator xmlIt(node, XmlNodeIterator::PreOrderMode);
+    XmlNode currentNode;
     while (xmlIt.getNext(currentNode)) {
         const std::string &currentName = currentNode.name();
         if (currentName == "color") {
@@ -1273,8 +1266,7 @@ void ColladaParser::ReadEffectParam(XmlNode &node, Collada::EffectParam &pParam)
         return;
     }
 
-    XmlNodeIterator xmlIt(node);
-    xmlIt.collectChildrenPreOrder(node);
+    XmlNodeIterator xmlIt(node, XmlNodeIterator::PreOrderMode);
     XmlNode currentNode;
     while (xmlIt.getNext(currentNode)) {
         const std::string &currentName = currentNode.name();
@@ -1360,8 +1352,7 @@ void ColladaParser::ReadMesh(XmlNode &node, Mesh &pMesh) {
         return;
     }
 
-    XmlNodeIterator xmlIt(node);
-    xmlIt.collectChildrenPreOrder(node);
+    XmlNodeIterator xmlIt(node, XmlNodeIterator::PreOrderMode);
     XmlNode currentNode;
     while (xmlIt.getNext(currentNode)) {
         const std::string &currentName = currentNode.name();
@@ -1386,8 +1377,7 @@ void ColladaParser::ReadSource(XmlNode &node) {
 
     std::string sourceID;
     XmlParser::getStdStrAttribute(node, "id", sourceID);
-    XmlNodeIterator xmlIt(node);
-    xmlIt.collectChildrenPreOrder(node);
+    XmlNodeIterator xmlIt(node, XmlNodeIterator::PreOrderMode);
     XmlNode currentNode;
     while (xmlIt.getNext(currentNode)) {
         const std::string &currentName = currentNode.name();
@@ -1490,8 +1480,7 @@ void ColladaParser::ReadAccessor(XmlNode &node, const std::string &pID) {
     acc.mSource = source.c_str() + 1; // ignore the leading '#'
     acc.mSize = 0; // gets incremented with every param
 
-    XmlNodeIterator xmlIt(node);
-    xmlIt.collectChildrenPreOrder(node);
+    XmlNodeIterator xmlIt(node, XmlNodeIterator::PreOrderMode);
     XmlNode currentNode;
     while (xmlIt.getNext(currentNode)) {
         const std::string &currentName = currentNode.name();
@@ -1608,8 +1597,7 @@ void ColladaParser::ReadIndexData(XmlNode &node, Mesh &pMesh) {
     ai_assert(primType != Prim_Invalid);
 
     // also a number of <input> elements, but in addition a <p> primitive collection and probably index counts for all primitives
-    XmlNodeIterator xmlIt(node);
-    xmlIt.collectChildrenPreOrder(node);
+    XmlNodeIterator xmlIt(node, XmlNodeIterator::PreOrderMode);
     XmlNode currentNode;
     while (xmlIt.getNext(currentNode)) {
         const std::string &currentName = currentNode.name();
@@ -2400,7 +2388,7 @@ Collada::InputType ColladaParser::GetTypeForSemantic(const std::string &semantic
     else if (semantic == "TANGENT" || semantic == "TEXTANGENT")
         return IT_Tangent;
 
-    ASSIMP_LOG_WARN_F("Unknown vertex input type \"", semantic, "\". Ignoring.");
+    ASSIMP_LOG_WARN("Unknown vertex input type \"", semantic, "\". Ignoring.");
     return IT_Invalid;
 }
 
diff --git a/code/AssetLib/DXF/DXFHelper.h b/code/AssetLib/DXF/DXFHelper.h
index f7fc470e8..c7e75c3b1 100644
--- a/code/AssetLib/DXF/DXFHelper.h
+++ b/code/AssetLib/DXF/DXFHelper.h
@@ -135,7 +135,7 @@ public:
                 for(;splitter->length() && splitter->at(0) != '}'; splitter++, cnt++);
 
                 splitter++;
-                ASSIMP_LOG_VERBOSE_DEBUG((Formatter::format("DXF: skipped over control group ("),cnt," lines)"));
+                ASSIMP_LOG_VERBOSE_DEBUG("DXF: skipped over control group (",cnt," lines)");
             }
         } catch(std::logic_error&) {
             ai_assert(!splitter);
diff --git a/code/AssetLib/DXF/DXFLoader.cpp b/code/AssetLib/DXF/DXFLoader.cpp
index d4a6be4ad..09c229265 100644
--- a/code/AssetLib/DXF/DXFLoader.cpp
+++ b/code/AssetLib/DXF/DXFLoader.cpp
@@ -202,7 +202,7 @@ void DXFImporter::InternReadFile( const std::string& filename, aiScene* pScene,
 
         // comments
         else if (reader.Is(999)) {
-            ASSIMP_LOG_INFO_F("DXF Comment: ", reader.Value());
+            ASSIMP_LOG_INFO("DXF Comment: ", reader.Value());
         }
 
         // don't read past the official EOF sign
@@ -241,7 +241,7 @@ void DXFImporter::ConvertMeshes(aiScene* pScene, DXF::FileData& output) {
             }
         }
 
-        ASSIMP_LOG_VERBOSE_DEBUG_F("DXF: Unexpanded polycount is ", icount, ", vertex count is ", vcount);
+        ASSIMP_LOG_VERBOSE_DEBUG("DXF: Unexpanded polycount is ", icount, ", vertex count is ", vcount);
     }
 
     if (! output.blocks.size()  ) {
@@ -372,7 +372,7 @@ void DXFImporter::ExpandBlockReferences(DXF::Block& bl,const DXF::BlockMap& bloc
         // first check if the referenced blocks exists ...
         const DXF::BlockMap::const_iterator it = blocks_by_name.find(insert.name);
         if (it == blocks_by_name.end()) {
-            ASSIMP_LOG_ERROR_F("DXF: Failed to resolve block reference: ", insert.name,"; skipping" );
+            ASSIMP_LOG_ERROR("DXF: Failed to resolve block reference: ", insert.name,"; skipping" );
             continue;
         }
 
@@ -473,7 +473,7 @@ void DXFImporter::ParseBlocks(DXF::LineReader& reader, DXF::FileData& output) {
         ++reader;
     }
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("DXF: got ", output.blocks.size()," entries in BLOCKS" );
+    ASSIMP_LOG_VERBOSE_DEBUG("DXF: got ", output.blocks.size()," entries in BLOCKS" );
 }
 
 // ------------------------------------------------------------------------------------------------
@@ -549,7 +549,7 @@ void DXFImporter::ParseEntities(DXF::LineReader& reader, DXF::FileData& output)
         ++reader;
     }
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F( "DXF: got ", block.lines.size()," polylines and ", block.insertions.size(), 
+    ASSIMP_LOG_VERBOSE_DEBUG( "DXF: got ", block.lines.size()," polylines and ", block.insertions.size(), 
         " inserted blocks in ENTITIES" );
 }
 
@@ -654,7 +654,7 @@ void DXFImporter::ParsePolyLine(DXF::LineReader& reader, DXF::FileData& output)
     //}
 
     if (vguess && line.positions.size() != vguess) {
-        ASSIMP_LOG_WARN_F("DXF: unexpected vertex count in polymesh: ",
+        ASSIMP_LOG_WARN("DXF: unexpected vertex count in polymesh: ",
             line.positions.size(),", expected ", vguess );
     }
 
@@ -670,7 +670,7 @@ void DXFImporter::ParsePolyLine(DXF::LineReader& reader, DXF::FileData& output)
         // to set the 71 and 72 fields, respectively, to valid values.
         // So just fire a warning.
         if (iguess && line.counts.size() != iguess) {
-            ASSIMP_LOG_WARN_F( "DXF: unexpected face count in polymesh: ", line.counts.size(),", expected ", iguess );
+            ASSIMP_LOG_WARN( "DXF: unexpected face count in polymesh: ", line.counts.size(),", expected ", iguess );
         }
     }
     else if (!line.indices.size() && !line.counts.size()) {
diff --git a/code/AssetLib/FBX/FBXBinaryTokenizer.cpp b/code/AssetLib/FBX/FBXBinaryTokenizer.cpp
index 800d0014d..348812054 100644
--- a/code/AssetLib/FBX/FBXBinaryTokenizer.cpp
+++ b/code/AssetLib/FBX/FBXBinaryTokenizer.cpp
@@ -459,7 +459,7 @@ void TokenizeBinary(TokenList& output_tokens, const char* input, size_t length)
 	/*Result ignored*/ ReadByte(input, cursor, input + length);
 	/*Result ignored*/ ReadByte(input, cursor, input + length);
 	const uint32_t version = ReadWord(input, cursor, input + length);
-	ASSIMP_LOG_DEBUG_F("FBX version: ", version);
+	ASSIMP_LOG_DEBUG("FBX version: ", version);
 	const bool is64bits = version >= 7500;
     const char *end = input + length;
     try
diff --git a/code/AssetLib/FBX/FBXConverter.cpp b/code/AssetLib/FBX/FBXConverter.cpp
index cb033a651..8d37d3790 100644
--- a/code/AssetLib/FBX/FBXConverter.cpp
+++ b/code/AssetLib/FBX/FBXConverter.cpp
@@ -811,7 +811,7 @@ bool FBXConverter::GenerateTransformationNodeChain(const Model &model, const std
     // we need to generate a full node chain to accommodate for assimp's
     // lack to express pivots and offsets.
     if ((chainBits & chainMaskComplex) && doc.Settings().preservePivots) {
-        FBXImporter::LogInfo("generating full transformation chain for node: " + name);
+        FBXImporter::LogInfo("generating full transformation chain for node: ", name);
 
         // query the anim_chain_bits dictionary to find out which chain elements
         // have associated node animation channels. These can not be dropped
@@ -918,7 +918,7 @@ void FBXConverter::ConvertModel(const Model &model, aiNode *parent, aiNode *root
             const std::vector<unsigned int> &indices = ConvertLine(*line, root_node);
             std::copy(indices.begin(), indices.end(), std::back_inserter(meshes));
         } else {
-            FBXImporter::LogWarn("ignoring unrecognized geometry: " + geo->Name());
+            FBXImporter::LogWarn("ignoring unrecognized geometry: ", geo->Name());
         }
     }
 
@@ -944,7 +944,7 @@ FBXConverter::ConvertMesh(const MeshGeometry &mesh, const Model &model, aiNode *
     const std::vector<aiVector3D> &vertices = mesh.GetVertices();
     const std::vector<unsigned int> &faces = mesh.GetFaceIndexCounts();
     if (vertices.empty() || faces.empty()) {
-        FBXImporter::LogWarn("ignoring empty geometry: " + mesh.Name());
+        FBXImporter::LogWarn("ignoring empty geometry: ", mesh.Name());
         return temp;
     }
 
@@ -971,7 +971,7 @@ std::vector<unsigned int> FBXConverter::ConvertLine(const LineGeometry &line, ai
     const std::vector<aiVector3D> &vertices = line.GetVertices();
     const std::vector<int> &indices = line.GetIndices();
     if (vertices.empty() || indices.empty()) {
-        FBXImporter::LogWarn("ignoring empty line: " + line.Name());
+        FBXImporter::LogWarn("ignoring empty line: ", line.Name());
         return temp;
     }
 
@@ -1542,10 +1542,10 @@ void FBXConverter::ConvertCluster(std::vector<aiBone *> &local_mesh_bones, const
     aiBone *bone = nullptr;
 
     if (bone_map.count(deformer_name)) {
-        ASSIMP_LOG_VERBOSE_DEBUG_F("retrieved bone from lookup ", bone_name.C_Str(), ". Deformer:", deformer_name);
+        ASSIMP_LOG_VERBOSE_DEBUG("retrieved bone from lookup ", bone_name.C_Str(), ". Deformer:", deformer_name);
         bone = bone_map[deformer_name];
     } else {
-        ASSIMP_LOG_VERBOSE_DEBUG_F("created new bone ", bone_name.C_Str(), ". Deformer: ", deformer_name);
+        ASSIMP_LOG_VERBOSE_DEBUG("created new bone ", bone_name.C_Str(), ". Deformer: ", deformer_name);
         bone = new aiBone();
         bone->mName = bone_name;
 
@@ -1591,7 +1591,7 @@ void FBXConverter::ConvertCluster(std::vector<aiBone *> &local_mesh_bones, const
         bone_map.insert(std::pair<const std::string, aiBone *>(deformer_name, bone));
     }
 
-    ASSIMP_LOG_DEBUG_F("bone research: Indicies size: ", out_indices.size());
+    ASSIMP_LOG_DEBUG("bone research: Indicies size: ", out_indices.size());
 
     // lookup must be populated in case something goes wrong
     // this also allocates bones to mesh instance outside
@@ -1815,14 +1815,14 @@ void FBXConverter::TrySetTextureProperties(aiMaterial *out_mat, const TextureMap
                             }
                         }
                         if (index == -1) {
-                            FBXImporter::LogWarn("did not find UV channel named " + uvSet + " in a mesh using this material");
+                            FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                             continue;
                         }
 
                         if (uvIndex == -1) {
                             uvIndex = index;
                         } else {
-                            FBXImporter::LogWarn("the UV channel named " + uvSet +
+                            FBXImporter::LogWarn("the UV channel named ", uvSet,
                                                  " appears at different positions in meshes, results will be wrong");
                         }
                     }
@@ -1839,7 +1839,7 @@ void FBXConverter::TrySetTextureProperties(aiMaterial *out_mat, const TextureMap
                         }
                     }
                     if (index == -1) {
-                        FBXImporter::LogWarn("did not find UV channel named " + uvSet + " in a mesh using this material");
+                        FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                     }
 
                     if (uvIndex == -1) {
@@ -1848,7 +1848,7 @@ void FBXConverter::TrySetTextureProperties(aiMaterial *out_mat, const TextureMap
                 }
 
                 if (uvIndex == -1) {
-                    FBXImporter::LogWarn("failed to resolve UV channel " + uvSet + ", using first UV channel");
+                    FBXImporter::LogWarn("failed to resolve UV channel ", uvSet, ", using first UV channel");
                     uvIndex = 0;
                 }
             }
@@ -1934,14 +1934,14 @@ void FBXConverter::TrySetTextureProperties(aiMaterial *out_mat, const LayeredTex
                             }
                         }
                         if (index == -1) {
-                            FBXImporter::LogWarn("did not find UV channel named " + uvSet + " in a mesh using this material");
+                            FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                             continue;
                         }
 
                         if (uvIndex == -1) {
                             uvIndex = index;
                         } else {
-                            FBXImporter::LogWarn("the UV channel named " + uvSet +
+                            FBXImporter::LogWarn("the UV channel named ", uvSet,
                                                  " appears at different positions in meshes, results will be wrong");
                         }
                     }
@@ -1958,7 +1958,7 @@ void FBXConverter::TrySetTextureProperties(aiMaterial *out_mat, const LayeredTex
                         }
                     }
                     if (index == -1) {
-                        FBXImporter::LogWarn("did not find UV channel named " + uvSet + " in a mesh using this material");
+                        FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                     }
 
                     if (uvIndex == -1) {
@@ -1967,7 +1967,7 @@ void FBXConverter::TrySetTextureProperties(aiMaterial *out_mat, const LayeredTex
                 }
 
                 if (uvIndex == -1) {
-                    FBXImporter::LogWarn("failed to resolve UV channel " + uvSet + ", using first UV channel");
+                    FBXImporter::LogWarn("failed to resolve UV channel ", uvSet, ", using first UV channel");
                     uvIndex = 0;
                 }
             }
@@ -2319,14 +2319,14 @@ void FBXConverter::SetShadingPropertiesRaw(aiMaterial *out_mat, const PropertyTa
                                 }
                             }
                             if (index == -1) {
-                                FBXImporter::LogWarn("did not find UV channel named " + uvSet + " in a mesh using this material");
+                                FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                                 continue;
                             }
 
                             if (uvIndex == -1) {
                                 uvIndex = index;
                             } else {
-                                FBXImporter::LogWarn("the UV channel named " + uvSet + " appears at different positions in meshes, results will be wrong");
+                                FBXImporter::LogWarn("the UV channel named ", uvSet, " appears at different positions in meshes, results will be wrong");
                             }
                         }
                     } else {
@@ -2342,7 +2342,7 @@ void FBXConverter::SetShadingPropertiesRaw(aiMaterial *out_mat, const PropertyTa
                             }
                         }
                         if (index == -1) {
-                            FBXImporter::LogWarn("did not find UV channel named " + uvSet + " in a mesh using this material");
+                            FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                         }
 
                         if (uvIndex == -1) {
@@ -2351,7 +2351,7 @@ void FBXConverter::SetShadingPropertiesRaw(aiMaterial *out_mat, const PropertyTa
                     }
 
                     if (uvIndex == -1) {
-                        FBXImporter::LogWarn("failed to resolve UV channel " + uvSet + ", using first UV channel");
+                        FBXImporter::LogWarn("failed to resolve UV channel ", uvSet, ", using first UV channel");
                         uvIndex = 0;
                     }
                 }
@@ -2574,7 +2574,7 @@ void FBXConverter::ConvertAnimationStack(const AnimationStack &st) {
         // empty animations would fail validation, so drop them
         delete anim;
         animations.pop_back();
-        FBXImporter::LogInfo("ignoring empty AnimationStack (using IK?): " + name);
+        FBXImporter::LogInfo("ignoring empty AnimationStack (using IK?): ", name);
         return;
     }
 
@@ -2707,13 +2707,13 @@ void FBXConverter::GenerateNodeAnimations(std::vector<aiNodeAnim *> &node_anims,
         ai_assert(node);
 
         if (node->TargetProperty().empty()) {
-            FBXImporter::LogWarn("target property for animation curve not set: " + node->Name());
+            FBXImporter::LogWarn("target property for animation curve not set: ", node->Name());
             continue;
         }
 
         curve_node = node;
         if (node->Curves().empty()) {
-            FBXImporter::LogWarn("no animation curves assigned to AnimationCurveNode: " + node->Name());
+            FBXImporter::LogWarn("no animation curves assigned to AnimationCurveNode: ", node->Name());
             continue;
         }
 
@@ -2748,7 +2748,7 @@ void FBXConverter::GenerateNodeAnimations(std::vector<aiNodeAnim *> &node_anims,
             if (doc.Settings().optimizeEmptyAnimationCurves &&
                     IsRedundantAnimationData(target, comp, (chain[i]->second))) {
 
-                FBXImporter::LogVerboseDebug("dropping redundant animation channel for node " + target.Name());
+                FBXImporter::LogVerboseDebug("dropping redundant animation channel for node ", target.Name());
                 continue;
             }
 
diff --git a/code/AssetLib/FBX/FBXDocument.cpp b/code/AssetLib/FBX/FBXDocument.cpp
index a9eb3ad15..7adaadf6c 100644
--- a/code/AssetLib/FBX/FBXDocument.cpp
+++ b/code/AssetLib/FBX/FBXDocument.cpp
@@ -312,7 +312,7 @@ void Document::ReadHeader() {
 
     const Scope& shead = *ehead->Compound();
     fbxVersion = ParseTokenAsInt(GetRequiredToken(GetRequiredElement(shead,"FBXVersion",ehead),0));
-	ASSIMP_LOG_DEBUG_F("FBX Version: ", fbxVersion);
+	ASSIMP_LOG_DEBUG("FBX Version: ", fbxVersion);
 
     // While we may have some success with newer files, we don't support
     // the older 6.n fbx format
diff --git a/code/AssetLib/FBX/FBXDocumentUtil.cpp b/code/AssetLib/FBX/FBXDocumentUtil.cpp
index 6ba01aa47..ab15298a8 100644
--- a/code/AssetLib/FBX/FBXDocumentUtil.cpp
+++ b/code/AssetLib/FBX/FBXDocumentUtil.cpp
@@ -79,7 +79,7 @@ void DOMError(const std::string& message, const Element* element /*= nullptr*/)
 void DOMWarning(const std::string& message, const Token& token)
 {
     if(DefaultLogger::get()) {
-        ASSIMP_LOG_WARN_F("FBX-DOM", Util::GetTokenText(&token), message);
+        ASSIMP_LOG_WARN("FBX-DOM", Util::GetTokenText(&token), message);
     }
 }
 
@@ -91,7 +91,7 @@ void DOMWarning(const std::string& message, const Element* element /*= nullptr*/
         return;
     }
     if(DefaultLogger::get()) {
-        ASSIMP_LOG_WARN("FBX-DOM: " + message);
+        ASSIMP_LOG_WARN("FBX-DOM: ", message);
     }
 }
 
diff --git a/code/AssetLib/FBX/FBXExporter.cpp b/code/AssetLib/FBX/FBXExporter.cpp
index 322161411..e519f7e77 100644
--- a/code/AssetLib/FBX/FBXExporter.cpp
+++ b/code/AssetLib/FBX/FBXExporter.cpp
@@ -1789,13 +1789,13 @@ void FBXExporter::WriteObjects ()
             blendchannel_uid, blendshape_name + FBX::SEPARATOR + "SubDeformer", "BlendShapeChannel"
         );
         sdnode.AddChild("Version", int32_t(100));
-        sdnode.AddChild("DeformPercent", int32_t(100));
+        sdnode.AddChild("DeformPercent", float_t(0.0));
         FBX::Node p("Properties70");
-        p.AddP70numberA("DeformPercent", 100.);
+        p.AddP70numberA("DeformPercent", 0.0);
         sdnode.AddChild(p);
         // TODO: Normally just one weight per channel, adding stub for later development
         std::vector<float>fFullWeights;
-        fFullWeights.push_back(0.);
+        fFullWeights.push_back(100.);
         sdnode.AddChild("FullWeights", fFullWeights);
         sdnode.Dump(outstream, binary, indent);
 
diff --git a/code/AssetLib/FBX/FBXMaterial.cpp b/code/AssetLib/FBX/FBXMaterial.cpp
index 3af014bc3..6ada9630b 100644
--- a/code/AssetLib/FBX/FBXMaterial.cpp
+++ b/code/AssetLib/FBX/FBXMaterial.cpp
@@ -82,7 +82,7 @@ Material::Material(uint64_t id, const Element& element, const Document& doc, con
 
     // lower-case shading because Blender (for example) writes "Phong"
     for (size_t i = 0; i < shading.length(); ++i) {
-        shading[i] = static_cast<char>(tolower(shading[i]));
+        shading[i] = static_cast<char>(tolower(static_cast<unsigned char>(shading[i])));
     }
     std::string templateName;
     if(shading == "phong") {
@@ -352,7 +352,7 @@ Video::Video(uint64_t id, const Element& element, const Document& doc, const std
             }
         } catch (const runtime_error& runtimeError) {
             //we don't need the content data for contents that has already been loaded
-            ASSIMP_LOG_VERBOSE_DEBUG_F("Caught exception in FBXMaterial (likely because content was already loaded): ",
+            ASSIMP_LOG_VERBOSE_DEBUG("Caught exception in FBXMaterial (likely because content was already loaded): ",
                     runtimeError.what());
         }
     }
diff --git a/code/AssetLib/FBX/FBXMeshGeometry.cpp b/code/AssetLib/FBX/FBXMeshGeometry.cpp
index fd8a0ff98..9bafcbd2a 100644
--- a/code/AssetLib/FBX/FBXMeshGeometry.cpp
+++ b/code/AssetLib/FBX/FBXMeshGeometry.cpp
@@ -307,8 +307,8 @@ void MeshGeometry::ReadLayerElement(const Scope& layerElement)
         }
     }
 
-    FBXImporter::LogError(Formatter::format("failed to resolve vertex layer element: ")
-        << type << ", index: " << typedIndex);
+    FBXImporter::LogError("failed to resolve vertex layer element: ",
+        type, ", index: ", typedIndex);
 }
 
 // ------------------------------------------------------------------------------------------------
@@ -324,13 +324,13 @@ void MeshGeometry::ReadVertexData(const std::string& type, int index, const Scop
 
     if (type == "LayerElementUV") {
         if(index >= AI_MAX_NUMBER_OF_TEXTURECOORDS) {
-            FBXImporter::LogError(Formatter::format("ignoring UV layer, maximum number of UV channels exceeded: ")
-                << index << " (limit is " << AI_MAX_NUMBER_OF_TEXTURECOORDS << ")" );
+            FBXImporter::LogError("ignoring UV layer, maximum number of UV channels exceeded: ",
+                index, " (limit is ", AI_MAX_NUMBER_OF_TEXTURECOORDS, ")" );
             return;
         }
 
         const Element* Name = source["Name"];
-        m_uvNames[index] = "";
+        m_uvNames[index] = std::string();
         if(Name) {
             m_uvNames[index] = ParseTokenAsString(GetRequiredToken(*Name,0));
         }
@@ -402,8 +402,8 @@ void MeshGeometry::ReadVertexData(const std::string& type, int index, const Scop
     }
     else if (type == "LayerElementColor") {
         if(index >= AI_MAX_NUMBER_OF_COLOR_SETS) {
-            FBXImporter::LogError(Formatter::format("ignoring vertex color layer, maximum number of color sets exceeded: ")
-                << index << " (limit is " << AI_MAX_NUMBER_OF_COLOR_SETS << ")" );
+            FBXImporter::LogError("ignoring vertex color layer, maximum number of color sets exceeded: ",
+                index, " (limit is ", AI_MAX_NUMBER_OF_COLOR_SETS, ")" );
             return;
         }
 
@@ -449,8 +449,8 @@ void ResolveVertexDataArray(std::vector<T>& data_out, const Scope& source,
         ParseVectorDataArray(tempData, GetRequiredElement(source, dataElementName));
 
         if (tempData.size() != mapping_offsets.size()) {
-            FBXImporter::LogError(Formatter::format("length of input data unexpected for ByVertice mapping: ")
-                                  << tempData.size() << ", expected " << mapping_offsets.size());
+            FBXImporter::LogError("length of input data unexpected for ByVertice mapping: ",
+                                  tempData.size(), ", expected ", mapping_offsets.size());
             return;
         }
 
@@ -470,8 +470,8 @@ void ResolveVertexDataArray(std::vector<T>& data_out, const Scope& source,
         ParseVectorDataArray(uvIndices,GetRequiredElement(source,indexDataElementName));
 
         if (uvIndices.size() != vertex_count) {
-            FBXImporter::LogError(Formatter::format("length of input data unexpected for ByVertice mapping: ")
-                                  << uvIndices.size() << ", expected " << vertex_count);
+            FBXImporter::LogError("length of input data unexpected for ByVertice mapping: ",
+                                  uvIndices.size(), ", expected ", vertex_count);
             return;
         }
 
@@ -493,8 +493,8 @@ void ResolveVertexDataArray(std::vector<T>& data_out, const Scope& source,
 		ParseVectorDataArray(tempData, GetRequiredElement(source, dataElementName));
 
 		if (tempData.size() != vertex_count) {
-            FBXImporter::LogError(Formatter::format("length of input data unexpected for ByPolygon mapping: ")
-				<< tempData.size() << ", expected " << vertex_count
+            FBXImporter::LogError("length of input data unexpected for ByPolygon mapping: ",
+				tempData.size(), ", expected ", vertex_count
             );
             return;
         }
@@ -509,14 +509,14 @@ void ResolveVertexDataArray(std::vector<T>& data_out, const Scope& source,
         ParseVectorDataArray(uvIndices,GetRequiredElement(source,indexDataElementName));
 
         if (uvIndices.size() > vertex_count) {
-            FBXImporter::LogWarn(Formatter::format("trimming length of input array for ByPolygonVertex mapping: ")
-                                          << uvIndices.size() << ", expected " << vertex_count);
+            FBXImporter::LogWarn("trimming length of input array for ByPolygonVertex mapping: ",
+                                          uvIndices.size(), ", expected ", vertex_count);
             uvIndices.resize(vertex_count);
         }
 
         if (uvIndices.size() != vertex_count) {
-            FBXImporter::LogError(Formatter::format("length of input data unexpected for ByPolygonVertex mapping: ")
-                                  << uvIndices.size() << ", expected " << vertex_count);
+            FBXImporter::LogError("length of input data unexpected for ByPolygonVertex mapping: ",
+                                  uvIndices.size(), ", expected ", vertex_count);
             return;
         }
 
@@ -537,8 +537,8 @@ void ResolveVertexDataArray(std::vector<T>& data_out, const Scope& source,
         }
     }
     else {
-        FBXImporter::LogError(Formatter::format("ignoring vertex data channel, access type not implemented: ")
-            << MappingInformationType << "," << ReferenceInformationType);
+        FBXImporter::LogError("ignoring vertex data channel, access type not implemented: ",
+            MappingInformationType, ",", ReferenceInformationType);
     }
 }
 
@@ -642,10 +642,10 @@ void MeshGeometry::ReadVertexDataMaterials(std::vector<int>& materials_out, cons
     if (MappingInformationType == "AllSame") {
         // easy - same material for all faces
         if (materials_out.empty()) {
-            FBXImporter::LogError(Formatter::format("expected material index, ignoring"));
+            FBXImporter::LogError("expected material index, ignoring");
             return;
         } else if (materials_out.size() > 1) {
-            FBXImporter::LogWarn(Formatter::format("expected only a single material index, ignoring all except the first one"));
+            FBXImporter::LogWarn("expected only a single material index, ignoring all except the first one");
             materials_out.clear();
         }
 
@@ -655,14 +655,14 @@ void MeshGeometry::ReadVertexDataMaterials(std::vector<int>& materials_out, cons
         materials_out.resize(face_count);
 
         if(materials_out.size() != face_count) {
-            FBXImporter::LogError(Formatter::format("length of input data unexpected for ByPolygon mapping: ")
-                << materials_out.size() << ", expected " << face_count
+            FBXImporter::LogError("length of input data unexpected for ByPolygon mapping: ",
+                materials_out.size(), ", expected ", face_count
             );
             return;
         }
     } else {
-        FBXImporter::LogError(Formatter::format("ignoring material assignments, access type not implemented: ")
-            << MappingInformationType << "," << ReferenceInformationType);
+        FBXImporter::LogError("ignoring material assignments, access type not implemented: ",
+            MappingInformationType, ",", ReferenceInformationType);
     }
 }
 // ------------------------------------------------------------------------------------------------
diff --git a/code/AssetLib/FBX/FBXParser.cpp b/code/AssetLib/FBX/FBXParser.cpp
index 046d26c95..37cf83cf9 100644
--- a/code/AssetLib/FBX/FBXParser.cpp
+++ b/code/AssetLib/FBX/FBXParser.cpp
@@ -462,7 +462,7 @@ std::string ParseTokenAsString(const Token& t, const char*& err_out)
 
     if (t.Type() != TokenType_DATA) {
         err_out = "expected TOK_DATA token";
-        return "";
+        return std::string();
     }
 
     if(t.IsBinary())
@@ -470,7 +470,7 @@ std::string ParseTokenAsString(const Token& t, const char*& err_out)
         const char* data = t.begin();
         if (data[0] != 'S') {
             err_out = "failed to parse S(tring), unexpected data type (binary)";
-            return "";
+            return std::string();
         }
 
         // read string length
@@ -484,13 +484,13 @@ std::string ParseTokenAsString(const Token& t, const char*& err_out)
     const size_t length = static_cast<size_t>(t.end() - t.begin());
     if(length < 2) {
         err_out = "token is too short to hold a string";
-        return "";
+        return std::string();
     }
 
     const char* s = t.begin(), *e = t.end() - 1;
     if (*s != '\"' || *e != '\"') {
         err_out = "expected double quoted string";
-        return "";
+        return std::string();
     }
 
     return std::string(s+1,length-2);
diff --git a/code/AssetLib/FBX/FBXProperties.cpp b/code/AssetLib/FBX/FBXProperties.cpp
index 2f39fc7dc..1e4cd0ead 100644
--- a/code/AssetLib/FBX/FBXProperties.cpp
+++ b/code/AssetLib/FBX/FBXProperties.cpp
@@ -155,7 +155,7 @@ std::string PeekPropertyName(const Element& element)
     ai_assert(element.KeyToken().StringContents() == "P");
     const TokenList& tok = element.Tokens();
     if(tok.size() < 4) {
-        return "";
+        return std::string();
     }
 
     return ParseTokenAsString(*tok[0]);
diff --git a/code/AssetLib/HMP/HMPLoader.cpp b/code/AssetLib/HMP/HMPLoader.cpp
index 56401f5c9..cd14cb9c3 100644
--- a/code/AssetLib/HMP/HMPLoader.cpp
+++ b/code/AssetLib/HMP/HMPLoader.cpp
@@ -47,6 +47,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "AssetLib/HMP/HMPLoader.h"
 #include "AssetLib/MD2/MD2FileData.h"
 
+#include <assimp/StringUtils.h>
 #include <assimp/importerdesc.h>
 #include <assimp/scene.h>
 #include <assimp/DefaultLogger.hpp>
@@ -151,12 +152,7 @@ void HMPImporter::InternReadFile(const std::string &pFile,
         InternReadFile_HMP7();
     } else {
         // Print the magic word to the logger
-        char szBuffer[5];
-        szBuffer[0] = ((char *)&iMagic)[0];
-        szBuffer[1] = ((char *)&iMagic)[1];
-        szBuffer[2] = ((char *)&iMagic)[2];
-        szBuffer[3] = ((char *)&iMagic)[3];
-        szBuffer[4] = '\0';
+        std::string szBuffer = ai_str_toprintable((const char *)&iMagic, sizeof(iMagic));
     
         delete[] mBuffer;
         mBuffer = nullptr;
diff --git a/code/AssetLib/IFC/IFCBoolean.cpp b/code/AssetLib/IFC/IFCBoolean.cpp
index 6015920c1..86cac7f46 100644
--- a/code/AssetLib/IFC/IFCBoolean.cpp
+++ b/code/AssetLib/IFC/IFCBoolean.cpp
@@ -715,7 +715,7 @@ void ProcessBoolean(const Schema_2x3::IfcBooleanResult &boolean, TempMesh &resul
     //   DIFFERENCE
     if (const Schema_2x3::IfcBooleanResult *const clip = boolean.ToPtr<Schema_2x3::IfcBooleanResult>()) {
         if (clip->Operator != "DIFFERENCE") {
-            IFCImporter::LogWarn("encountered unsupported boolean operator: " + (std::string)clip->Operator);
+            IFCImporter::LogWarn("encountered unsupported boolean operator: ", (std::string)clip->Operator);
             return;
         }
 
@@ -756,7 +756,7 @@ void ProcessBoolean(const Schema_2x3::IfcBooleanResult &boolean, TempMesh &resul
             ProcessBooleanExtrudedAreaSolidDifference(as, result, first_operand, conv);
         }
     } else {
-        IFCImporter::LogWarn("skipping unknown IfcBooleanResult entity, type is " + boolean.GetClassName());
+        IFCImporter::LogWarn("skipping unknown IfcBooleanResult entity, type is ", boolean.GetClassName());
     }
 }
 
diff --git a/code/AssetLib/IFC/IFCGeometry.cpp b/code/AssetLib/IFC/IFCGeometry.cpp
index 664444443..6e645f1ae 100644
--- a/code/AssetLib/IFC/IFCGeometry.cpp
+++ b/code/AssetLib/IFC/IFCGeometry.cpp
@@ -216,7 +216,7 @@ void ProcessConnectedFaceSet(const Schema_2x3::IfcConnectedFaceSet& fset, TempMe
                 }
             }
             else {
-                IFCImporter::LogWarn("skipping unknown IfcFaceBound entity, type is " + bound.Bound->GetClassName());
+                IFCImporter::LogWarn("skipping unknown IfcFaceBound entity, type is ", bound.Bound->GetClassName());
                 continue;
             }
 
@@ -729,7 +729,7 @@ void ProcessSweptAreaSolid(const Schema_2x3::IfcSweptAreaSolid& swept, TempMesh&
         ProcessRevolvedAreaSolid(*rev,meshout,conv);
     }
     else {
-        IFCImporter::LogWarn("skipping unknown IfcSweptAreaSolid entity, type is " + swept.GetClassName());
+        IFCImporter::LogWarn("skipping unknown IfcSweptAreaSolid entity, type is ", swept.GetClassName());
     }
 }
 
@@ -781,7 +781,7 @@ bool ProcessGeometricItem(const Schema_2x3::IfcRepresentationItem& geo, unsigned
         return false;
     }
     else {
-        IFCImporter::LogWarn("skipping unknown IfcGeometricRepresentationItem entity, type is " + geo.GetClassName());
+        IFCImporter::LogWarn("skipping unknown IfcGeometricRepresentationItem entity, type is ", geo.GetClassName());
         return false;
     }
 
diff --git a/code/AssetLib/IFC/IFCLoader.cpp b/code/AssetLib/IFC/IFCLoader.cpp
index be100df57..daf2cc946 100644
--- a/code/AssetLib/IFC/IFCLoader.cpp
+++ b/code/AssetLib/IFC/IFCLoader.cpp
@@ -115,7 +115,7 @@ static const aiImporterDesc desc = {
     0,
     0,
     0,
-    "ifc ifczip stp"
+    "ifc ifczip step stp"
 };
 
 // ------------------------------------------------------------------------------------------------
@@ -243,12 +243,12 @@ void IFCImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
     }
 
     if (!DefaultLogger::isNullLogger()) {
-        LogDebug("File schema is \'" + head.fileSchema + '\'');
+        LogDebug("File schema is \'", head.fileSchema, '\'');
         if (head.timestamp.length()) {
-            LogDebug("Timestamp \'" + head.timestamp + '\'');
+            LogDebug("Timestamp \'", head.timestamp, '\'');
         }
         if (head.app.length()) {
-            LogDebug("Application/Exporter identline is \'" + head.app + '\'');
+            LogDebug("Application/Exporter identline is \'", head.app, '\'');
         }
     }
 
@@ -315,7 +315,7 @@ void IFCImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 
     // this must be last because objects are evaluated lazily as we process them
     if (!DefaultLogger::isNullLogger()) {
-        LogDebug((Formatter::format(), "STEP: evaluated ", db->GetEvaluatedObjectCount(), " object records"));
+        LogDebug("STEP: evaluated ", db->GetEvaluatedObjectCount(), " object records");
     }
 }
 
@@ -403,7 +403,7 @@ void ResolveObjectPlacement(aiMatrix4x4 &m, const Schema_2x3::IfcObjectPlacement
             m = tmpM * m;
         }
     } else {
-        IFCImporter::LogWarn("skipping unknown IfcObjectPlacement entity, type is " + place.GetClassName());
+        IFCImporter::LogWarn("skipping unknown IfcObjectPlacement entity, type is ", place.GetClassName());
     }
 }
 
@@ -438,7 +438,7 @@ bool ProcessMappedItem(const Schema_2x3::IfcMappedItem &mapped, aiNode *nd_src,
     bool got = false;
     for (const Schema_2x3::IfcRepresentationItem &item : repr.Items) {
         if (!ProcessRepresentationItem(item, localmatid, meshes, conv)) {
-            IFCImporter::LogWarn("skipping mapped entity of type " + item.GetClassName() + ", no representations could be generated");
+            IFCImporter::LogWarn("skipping mapped entity of type ", item.GetClassName(), ", no representations could be generated");
         } else
             got = true;
     }
@@ -567,7 +567,7 @@ typedef std::map<std::string, std::string> Metadata;
 
 // ------------------------------------------------------------------------------------------------
 void ProcessMetadata(const Schema_2x3::ListOf<Schema_2x3::Lazy<Schema_2x3::IfcProperty>, 1, 0> &set, ConversionData &conv, Metadata &properties,
-        const std::string &prefix = "",
+        const std::string &prefix = std::string(),
         unsigned int nest = 0) {
     for (const Schema_2x3::IfcProperty &property : set) {
         const std::string &key = prefix.length() > 0 ? (prefix + "." + property.Name) : property.Name;
@@ -618,7 +618,7 @@ void ProcessMetadata(const Schema_2x3::ListOf<Schema_2x3::Lazy<Schema_2x3::IfcPr
                 ProcessMetadata(complexProp->HasProperties, conv, properties, key, nest + 1);
             }
         } else {
-            properties[key] = "";
+            properties[key] = std::string();
         }
     }
 }
@@ -856,7 +856,7 @@ void ProcessSpatialStructures(ConversionData &conv) {
         if (!prod) {
             continue;
         }
-        IFCImporter::LogVerboseDebug("looking at spatial structure `" + (prod->Name ? prod->Name.Get() : "unnamed") + "`" + (prod->ObjectType ? " which is of type " + prod->ObjectType.Get() : ""));
+        IFCImporter::LogVerboseDebug("looking at spatial structure `", (prod->Name ? prod->Name.Get() : "unnamed"), "`", (prod->ObjectType ? " which is of type " + prod->ObjectType.Get() : ""));
 
         // the primary sites are referenced by an IFCRELAGGREGATES element which assigns them to the IFCPRODUCT
         const STEP::DB::RefMap &refs = conv.db.GetRefs();
diff --git a/code/AssetLib/IFC/IFCMaterial.cpp b/code/AssetLib/IFC/IFCMaterial.cpp
index e0146b887..2a79f0754 100644
--- a/code/AssetLib/IFC/IFCMaterial.cpp
+++ b/code/AssetLib/IFC/IFCMaterial.cpp
@@ -64,7 +64,7 @@ static int ConvertShadingMode(const std::string& name) {
     else if (name == "PHONG") {
         return aiShadingMode_Phong;
     }
-    IFCImporter::LogWarn("shading mode "+name+" not recognized by Assimp, using Phong instead");
+    IFCImporter::LogWarn("shading mode ", name, " not recognized by Assimp, using Phong instead");
     return aiShadingMode_Phong;
 }
 
@@ -145,7 +145,7 @@ unsigned int ProcessMaterials(uint64_t id, unsigned int prevMatId, ConversionDat
                         // not found, create new material
                         const std::string side = static_cast<std::string>(surf->Side);
                         if( side != "BOTH" ) {
-                            IFCImporter::LogWarn("ignoring surface side marker on IFC::IfcSurfaceStyle: " + side);
+                            IFCImporter::LogWarn("ignoring surface side marker on IFC::IfcSurfaceStyle: ", side);
                         }
 
                         std::unique_ptr<aiMaterial> mat(new aiMaterial());
diff --git a/code/AssetLib/IFC/IFCProfile.cpp b/code/AssetLib/IFC/IFCProfile.cpp
index f33f8cdbe..4235be181 100644
--- a/code/AssetLib/IFC/IFCProfile.cpp
+++ b/code/AssetLib/IFC/IFCProfile.cpp
@@ -68,7 +68,7 @@ bool ProcessCurve(const Schema_2x3::IfcCurve& curve,  TempMesh& meshout, Convers
 {
     std::unique_ptr<const Curve> cv(Curve::Convert(curve,conv));
     if (!cv) {
-        IFCImporter::LogWarn("skipping unknown IfcCurve entity, type is " + curve.GetClassName());
+        IFCImporter::LogWarn("skipping unknown IfcCurve entity, type is ", curve.GetClassName());
         return false;
     }
 
@@ -78,7 +78,7 @@ bool ProcessCurve(const Schema_2x3::IfcCurve& curve,  TempMesh& meshout, Convers
             bc->SampleDiscrete(meshout);
         }
         catch(const  CurveError& cv) {
-            IFCImporter::LogError(cv.mStr + " (error occurred while processing curve)");
+            IFCImporter::LogError(cv.mStr, " (error occurred while processing curve)");
             return false;
         }
         meshout.mVertcnt.push_back(static_cast<unsigned int>(meshout.mVerts.size()));
@@ -152,7 +152,7 @@ void ProcessParametrizedProfile(const Schema_2x3::IfcParameterizedProfileDef& de
         meshout.mVertcnt.push_back(12);
     }
     else {
-        IFCImporter::LogWarn("skipping unknown IfcParameterizedProfileDef entity, type is " + def.GetClassName());
+        IFCImporter::LogWarn("skipping unknown IfcParameterizedProfileDef entity, type is ", def.GetClassName());
         return;
     }
 
@@ -174,7 +174,7 @@ bool ProcessProfile(const Schema_2x3::IfcProfileDef& prof, TempMesh& meshout, Co
         ProcessParametrizedProfile(*cparam,meshout,conv);
     }
     else {
-        IFCImporter::LogWarn("skipping unknown IfcProfileDef entity, type is " + prof.GetClassName());
+        IFCImporter::LogWarn("skipping unknown IfcProfileDef entity, type is ", prof.GetClassName());
         return false;
     }
     meshout.RemoveAdjacentDuplicates();
diff --git a/code/AssetLib/IFC/IFCUtil.cpp b/code/AssetLib/IFC/IFCUtil.cpp
index b451262e9..8c37cebed 100644
--- a/code/AssetLib/IFC/IFCUtil.cpp
+++ b/code/AssetLib/IFC/IFCUtil.cpp
@@ -506,7 +506,7 @@ IfcFloat ConvertSIPrefix(const std::string& prefix)
         return 1e-18f;
     }
     else {
-        IFCImporter::LogError("Unrecognized SI prefix: " + prefix);
+        IFCImporter::LogError("Unrecognized SI prefix: ", prefix);
         return 1;
     }
 }
diff --git a/code/AssetLib/Irr/IRRLoader.cpp b/code/AssetLib/Irr/IRRLoader.cpp
index 9c1136499..cb383e936 100644
--- a/code/AssetLib/Irr/IRRLoader.cpp
+++ b/code/AssetLib/Irr/IRRLoader.cpp
@@ -639,7 +639,7 @@ void IRRImporter::GenerateGraph(Node *root, aiNode *rootOut, aiScene *scene,
 			// graph we're currently building
 			aiScene *localScene = batch.GetImport(root->id);
 			if (!localScene) {
-				ASSIMP_LOG_ERROR("IRR: Unable to load external file: " + root->meshPath);
+				ASSIMP_LOG_ERROR("IRR: Unable to load external file: ", root->meshPath);
 				break;
 			}
 			attach.push_back(AttachmentInfo(localScene, rootOut));
@@ -859,13 +859,13 @@ void IRRImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 
 	// Check whether we can read from the file
 	if (file.get() == nullptr) {
-		throw DeadlyImportError("Failed to open IRR file " + pFile + "");
+        throw DeadlyImportError("Failed to open IRR file ", pFile);
 	}
 
 	// Construct the irrXML parser
 	XmlParser st;
     if (!st.parse( file.get() )) {
-        return;
+        throw DeadlyImportError("XML parse error while loading IRR file ", pFile);
     }
     pugi::xml_node rootElement = st.getRootNode();
 
@@ -963,7 +963,7 @@ void IRRImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 						ASSIMP_LOG_ERROR("IRR: Billboards are not supported by Assimp");
 						nd = new Node(Node::DUMMY);
 					} else {
-						ASSIMP_LOG_WARN("IRR: Found unknown node: " + std::string(attrib.name()));
+						ASSIMP_LOG_WARN("IRR: Found unknown node: ", attrib.name());
 
 						/*  We skip the contents of nodes we don't know.
                          *  We parse the transformation and all animators
@@ -1181,7 +1181,7 @@ void IRRImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 											lights.pop_back();
 											curNode->type = Node::DUMMY;
 
-											ASSIMP_LOG_ERROR("Ignoring light of unknown type: " + prop.value);
+											ASSIMP_LOG_ERROR("Ignoring light of unknown type: ", prop.value);
 										}
 									} else if ((prop.name == "Mesh" && Node::MESH == curNode->type) ||
 											   Node::ANIMMESH == curNode->type) {
@@ -1225,7 +1225,7 @@ void IRRImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 										} else if (prop.value == "followSpline") {
 											curAnim->type = Animator::FOLLOW_SPLINE;
 										} else {
-											ASSIMP_LOG_WARN("IRR: Ignoring unknown animator: " + prop.value);
+											ASSIMP_LOG_WARN("IRR: Ignoring unknown animator: ", prop.value);
 
 											curAnim->type = Animator::UNKNOWN;
 										}
diff --git a/code/AssetLib/Irr/IRRMeshLoader.cpp b/code/AssetLib/Irr/IRRMeshLoader.cpp
index 97d74026f..9350e07b8 100644
--- a/code/AssetLib/Irr/IRRMeshLoader.cpp
+++ b/code/AssetLib/Irr/IRRMeshLoader.cpp
@@ -135,12 +135,12 @@ void IRRMeshImporter::InternReadFile(const std::string &pFile,
 
 	// Check whether we can read from the file
 	if (file.get() == NULL)
-		throw DeadlyImportError("Failed to open IRRMESH file " + pFile + "");
+        throw DeadlyImportError("Failed to open IRRMESH file ", pFile);
 
 	// Construct the irrXML parser
 	XmlParser parser;
     if (!parser.parse( file.get() )) {
-        return;
+        throw DeadlyImportError("XML parse error while loading IRRMESH file ", pFile);
     }
     XmlNode root = parser.getRootNode();
 
diff --git a/code/AssetLib/Irr/IRRShared.cpp b/code/AssetLib/Irr/IRRShared.cpp
index b119b063a..b42f34b65 100644
--- a/code/AssetLib/Irr/IRRShared.cpp
+++ b/code/AssetLib/Irr/IRRShared.cpp
@@ -260,7 +260,7 @@ aiMaterial* IrrlichtBase::ParseMaterial(unsigned int& matFlags) {
 							   prop.value == "parallaxmap_trans_add") {
 						matFlags = AI_IRRMESH_MAT_normalmap_ta;
 					} else {
-						ASSIMP_LOG_WARN("IRRMat: Unrecognized material type: " + prop.value);
+						ASSIMP_LOG_WARN("IRRMat: Unrecognized material type: ", prop.value);
 					}
 				}
 
diff --git a/code/AssetLib/LWO/LWOBLoader.cpp b/code/AssetLib/LWO/LWOBLoader.cpp
index 2654eccf4..8ef40fc21 100644
--- a/code/AssetLib/LWO/LWOBLoader.cpp
+++ b/code/AssetLib/LWO/LWOBLoader.cpp
@@ -242,7 +242,7 @@ LWO::Texture* LWOImporter::SetupNewTextureLWOB(LWO::TextureList& list,unsigned i
     else
     {
         // procedural or gradient, not supported
-        ASSIMP_LOG_ERROR_F("LWOB: Unsupported legacy texture: ", type);
+        ASSIMP_LOG_ERROR("LWOB: Unsupported legacy texture: ", type);
     }
 
     return tex;
diff --git a/code/AssetLib/LWO/LWOFileData.h b/code/AssetLib/LWO/LWOFileData.h
index 70642c537..93ac1a236 100644
--- a/code/AssetLib/LWO/LWOFileData.h
+++ b/code/AssetLib/LWO/LWOFileData.h
@@ -502,7 +502,7 @@ struct Surface {
     Surface() :
             mColor(0.78431f, 0.78431f, 0.78431f), bDoubleSided(false), mDiffuseValue(1.f), mSpecularValue(0.f), mTransparency(0.f), mGlossiness(0.4f), mLuminosity(0.f), mColorHighlights(0.f), mMaximumSmoothAngle(0.f) // 0 == not specified, no smoothing
             ,
-            mVCMap(""),
+            mVCMap(),
             mVCMapType(AI_LWO_RGBA),
             mIOR(1.f) // vakuum
             ,
diff --git a/code/AssetLib/LWO/LWOLoader.cpp b/code/AssetLib/LWO/LWOLoader.cpp
index a9fa08f11..bc62152c5 100644
--- a/code/AssetLib/LWO/LWOLoader.cpp
+++ b/code/AssetLib/LWO/LWOLoader.cpp
@@ -961,7 +961,7 @@ void LWOImporter::LoadLWO2VertexMap(unsigned int length, bool perPoly) {
     switch (type) {
         case AI_LWO_TXUV:
             if (dims != 2) {
-                ASSIMP_LOG_WARN("LWO2: Skipping UV channel \'" + name + "\' with !2 components");
+                ASSIMP_LOG_WARN("LWO2: Skipping UV channel \'", name, "\' with !2 components");
                 return;
             }
             base = FindEntry(mCurLayer->mUVChannels, name, perPoly);
@@ -969,7 +969,7 @@ void LWOImporter::LoadLWO2VertexMap(unsigned int length, bool perPoly) {
         case AI_LWO_WGHT:
         case AI_LWO_MNVW:
             if (dims != 1) {
-                ASSIMP_LOG_WARN("LWO2: Skipping Weight Channel \'" + name + "\' with !1 components");
+                ASSIMP_LOG_WARN("LWO2: Skipping Weight Channel \'", name, "\' with !1 components");
                 return;
             }
             base = FindEntry((type == AI_LWO_WGHT ? mCurLayer->mWeightChannels : mCurLayer->mSWeightChannels), name, perPoly);
@@ -977,7 +977,7 @@ void LWOImporter::LoadLWO2VertexMap(unsigned int length, bool perPoly) {
         case AI_LWO_RGB:
         case AI_LWO_RGBA:
             if (dims != 3 && dims != 4) {
-                ASSIMP_LOG_WARN("LWO2: Skipping Color Map \'" + name + "\' with a dimension > 4 or < 3");
+                ASSIMP_LOG_WARN("LWO2: Skipping Color Map \'", name, "\' with a dimension > 4 or < 3");
                 return;
             }
             base = FindEntry(mCurLayer->mVColorChannels, name, perPoly);
@@ -1006,7 +1006,7 @@ void LWOImporter::LoadLWO2VertexMap(unsigned int length, bool perPoly) {
             if (name == "APS.Level") {
                 // XXX handle this (seems to be subdivision-related).
             }
-            ASSIMP_LOG_WARN_F("LWO2: Skipping unknown VMAP/VMAD channel \'", name, "\'");
+            ASSIMP_LOG_WARN("LWO2: Skipping unknown VMAP/VMAD channel \'", name, "\'");
             return;
     };
     base->Allocate((unsigned int)mCurLayer->mTempPoints.size());
@@ -1026,7 +1026,7 @@ void LWOImporter::LoadLWO2VertexMap(unsigned int length, bool perPoly) {
 
         unsigned int idx = ReadVSizedIntLWO2(mFileBuffer) + mCurLayer->mPointIDXOfs;
         if (idx >= numPoints) {
-            ASSIMP_LOG_WARN_F("LWO2: Failure evaluating VMAP/VMAD entry \'", name, "\', vertex index is out of range");
+            ASSIMP_LOG_WARN("LWO2: Failure evaluating VMAP/VMAD entry \'", name, "\', vertex index is out of range");
             mFileBuffer += base->dims << 2u;
             continue;
         }
@@ -1036,7 +1036,7 @@ void LWOImporter::LoadLWO2VertexMap(unsigned int length, bool perPoly) {
                 // we have already a VMAP entry for this vertex - thus
                 // we need to duplicate the corresponding polygon.
                 if (polyIdx >= numFaces) {
-                    ASSIMP_LOG_WARN_F("LWO2: Failure evaluating VMAD entry \'", name, "\', polygon index is out of range");
+                    ASSIMP_LOG_WARN("LWO2: Failure evaluating VMAD entry \'", name, "\', polygon index is out of range");
                     mFileBuffer += base->dims << 2u;
                     continue;
                 }
@@ -1076,7 +1076,7 @@ void LWOImporter::LoadLWO2VertexMap(unsigned int length, bool perPoly) {
                     CreateNewEntry(mCurLayer->mNormals, srcIdx);
                 }
                 if (!had) {
-                    ASSIMP_LOG_WARN_F("LWO2: Failure evaluating VMAD entry \'", name, "\', vertex index wasn't found in that polygon");
+                    ASSIMP_LOG_WARN("LWO2: Failure evaluating VMAD entry \'", name, "\', vertex index wasn't found in that polygon");
                     ai_assert(had);
                 }
             }
diff --git a/code/AssetLib/LWO/LWOMaterial.cpp b/code/AssetLib/LWO/LWOMaterial.cpp
index 9d51438d7..178f24265 100644
--- a/code/AssetLib/LWO/LWOMaterial.cpp
+++ b/code/AssetLib/LWO/LWOMaterial.cpp
@@ -335,7 +335,7 @@ void LWOImporter::ConvertMaterial(const LWO::Surface &surf, aiMaterial *pcMat) {
             m = aiShadingMode_Fresnel;
             break;
         } else {
-            ASSIMP_LOG_WARN_F("LWO2: Unknown surface shader: ", shader.functionName);
+            ASSIMP_LOG_WARN("LWO2: Unknown surface shader: ", shader.functionName);
         }
     }
     if (surf.mMaximumSmoothAngle <= 0.0)
@@ -711,7 +711,7 @@ void LWOImporter::LoadLWO2Surface(unsigned int size) {
             }
         }
         if (derived.size()) {
-            ASSIMP_LOG_WARN("LWO2: Unable to find source surface: " + derived);
+            ASSIMP_LOG_WARN("LWO2: Unable to find source surface: ", derived);
         }
     }
 
diff --git a/code/AssetLib/LWS/LWSLoader.cpp b/code/AssetLib/LWS/LWSLoader.cpp
index a75b90ef9..d469a1064 100644
--- a/code/AssetLib/LWS/LWSLoader.cpp
+++ b/code/AssetLib/LWS/LWSLoader.cpp
@@ -346,7 +346,7 @@ void LWSImporter::BuildGraph(aiNode *nd, LWS::NodeDesc &src, std::vector<Attachm
         if (src.path.length()) {
             obj = batch.GetImport(src.id);
             if (!obj) {
-                ASSIMP_LOG_ERROR("LWS: Failed to read external file " + src.path);
+                ASSIMP_LOG_ERROR("LWS: Failed to read external file ", src.path);
             } else {
                 if (obj->mRootNode->mNumChildren == 1) {
 
@@ -538,7 +538,7 @@ void LWSImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
     // get file format version and print to log
     ++it;
     unsigned int version = strtoul10((*it).tokens[0].c_str());
-    ASSIMP_LOG_INFO("LWS file format version is " + (*it).tokens[0]);
+    ASSIMP_LOG_INFO("LWS file format version is ", (*it).tokens[0]);
     first = 0.;
     last = 60.;
     fps = 25.; // seems to be a good default frame rate
diff --git a/code/AssetLib/LWS/LWSLoader.h b/code/AssetLib/LWS/LWSLoader.h
index 93251cd5d..cd7a0543e 100644
--- a/code/AssetLib/LWS/LWSLoader.h
+++ b/code/AssetLib/LWS/LWSLoader.h
@@ -88,7 +88,7 @@ struct NodeDesc {
             id(),
             number(0),
             parent(0),
-            name(""),
+            name(),
             isPivotSet(false),
             lightColor(1.f, 1.f, 1.f),
             lightIntensity(1.f),
diff --git a/code/AssetLib/M3D/M3DExporter.cpp b/code/AssetLib/M3D/M3DExporter.cpp
index 856932947..bcac1d98a 100644
--- a/code/AssetLib/M3D/M3DExporter.cpp
+++ b/code/AssetLib/M3D/M3DExporter.cpp
@@ -294,21 +294,17 @@ void ExportSceneM3D(
 // Worker function for exporting a scene to ASCII A3D.
 // Prototyped and registered in Exporter.cpp
 void ExportSceneM3DA(
-        const char *,
-        IOSystem *,
-        const aiScene *,
-        const ExportProperties *
+        const char *pFile,
+        IOSystem *pIOSystem,
+        const aiScene *pScene,
+        const ExportProperties *pProperties
 
 ) {
-#ifdef M3D_ASCII
     // initialize the exporter
     M3DExporter exporter(pScene, pProperties);
 
     // perform ascii export
     exporter.doExport(pFile, pIOSystem, true);
-#else
-    throw DeadlyExportError("Assimp configured without M3D_ASCII support");
-#endif
 }
 
 // ------------------------------------------------------------------------------------------------
diff --git a/code/AssetLib/M3D/M3DImporter.cpp b/code/AssetLib/M3D/M3DImporter.cpp
index 8cbda23cb..38bbd1d4a 100644
--- a/code/AssetLib/M3D/M3DImporter.cpp
+++ b/code/AssetLib/M3D/M3DImporter.cpp
@@ -95,11 +95,7 @@ static const aiImporterDesc desc = {
     0,
     0,
     0,
-#ifdef M3D_ASCII
     "m3d a3d"
-#else
-    "m3d"
-#endif
 };
 
 namespace Assimp {
@@ -119,9 +115,7 @@ bool M3DImporter::CanRead(const std::string &pFile, IOSystem *pIOHandler, bool c
     const std::string extension = GetExtension(pFile);
 
     if (extension == "m3d"
-#ifdef M3D_ASCII
             || extension == "a3d"
-#endif
     )
         return true;
     else if (!extension.length() || checkSig) {
@@ -137,13 +131,11 @@ bool M3DImporter::CanRead(const std::string &pFile, IOSystem *pIOHandler, bool c
         */
         std::unique_ptr<IOStream> pStream(pIOHandler->Open(pFile, "rb"));
         unsigned char data[4];
-        if (4 != pStream->Read(data, 1, 4)) {
+        if (!pStream || 4 != pStream->Read(data, 1, 4)) {
             return false;
         }
         return !memcmp(data, "3DMO", 4) /* bin */
-#ifdef M3D_ASCII
                || !memcmp(data, "3dmo", 4) /* ASCII */
-#endif
                 ;
     }
     return false;
@@ -176,12 +168,10 @@ void M3DImporter::InternReadFile(const std::string &file, aiScene *pScene, IOSys
     if (!memcmp(buffer.data(), "3DMO", 4) && memcmp(buffer.data() + 4, &fileSize, 4)) {
         throw DeadlyImportError("Bad binary header in file ", file, ".");
     }
-#ifdef M3D_ASCII
     // make sure there's a terminator zero character, as input must be ASCIIZ
     if (!memcmp(buffer.data(), "3dmo", 4)) {
         buffer.push_back(0);
     }
-#endif
 
     // Get the path for external assets
     std::string folderName("./");
@@ -194,7 +184,7 @@ void M3DImporter::InternReadFile(const std::string &file, aiScene *pScene, IOSys
     }
 
     //DefaultLogger::create("/dev/stderr", Logger::VERBOSE);
-    ASSIMP_LOG_DEBUG_F("M3D: loading ", file);
+    ASSIMP_LOG_DEBUG("M3D: loading ", file);
 
     // let the C SDK do the hard work for us
     M3DWrapper m3d(pIOHandler, buffer);
@@ -210,7 +200,7 @@ void M3DImporter::InternReadFile(const std::string &file, aiScene *pScene, IOSys
     pScene->mRootNode->mNumChildren = 0;
     mScene = pScene;
 
-    ASSIMP_LOG_DEBUG("M3D: root node " + m3d.Name());
+    ASSIMP_LOG_DEBUG("M3D: root node ", m3d.Name());
 
     // now we just have to fill up the Assimp structures in pScene
     importMaterials(m3d);
@@ -240,7 +230,7 @@ void M3DImporter::importMaterials(const M3DWrapper &m3d) {
     mScene->mNumMaterials = m3d->nummaterial + 1;
     mScene->mMaterials = new aiMaterial *[mScene->mNumMaterials];
 
-    ASSIMP_LOG_DEBUG_F("M3D: importMaterials ", mScene->mNumMaterials);
+    ASSIMP_LOG_DEBUG("M3D: importMaterials ", mScene->mNumMaterials);
 
     // add a default material as first
     aiMaterial *mat = new aiMaterial;
@@ -335,7 +325,7 @@ void M3DImporter::importTextures(const M3DWrapper &m3d) {
     ai_assert(m3d);
 
     mScene->mNumTextures = m3d->numtexture;
-    ASSIMP_LOG_DEBUG_F("M3D: importTextures ", mScene->mNumTextures);
+    ASSIMP_LOG_DEBUG("M3D: importTextures ", mScene->mNumTextures);
 
     if (!m3d->numtexture || !m3d->texture) {
         return;
@@ -390,7 +380,7 @@ void M3DImporter::importTextures(const M3DWrapper &m3d) {
 // individually. In assimp there're per mesh vertex and UV lists, and they must be
 // indexed simultaneously.
 void M3DImporter::importMeshes(const M3DWrapper &m3d) {
-    ASSIMP_LOG_DEBUG_F("M3D: importMeshes ", m3d->numface);
+    ASSIMP_LOG_DEBUG("M3D: importMeshes ", m3d->numface);
 
     if (!m3d->numface || !m3d->face || !m3d->numvertex || !m3d->vertex) {
         return;
@@ -509,7 +499,7 @@ void M3DImporter::importBones(const M3DWrapper &m3d, unsigned int parentid, aiNo
     ai_assert(mScene != nullptr);
     ai_assert(m3d);
 
-    ASSIMP_LOG_DEBUG_F("M3D: importBones ", m3d->numbone, " parentid ", (int)parentid);
+    ASSIMP_LOG_DEBUG("M3D: importBones ", m3d->numbone, " parentid ", (int)parentid);
 
     if (!m3d->numbone || !m3d->bone) {
         return;
@@ -550,7 +540,7 @@ void M3DImporter::importAnimations(const M3DWrapper &m3d) {
 
     mScene->mNumAnimations = m3d->numaction;
 
-    ASSIMP_LOG_DEBUG_F("M3D: importAnimations ", mScene->mNumAnimations);
+    ASSIMP_LOG_DEBUG("M3D: importAnimations ", mScene->mNumAnimations);
 
     if (!m3d->numaction || !m3d->action || !m3d->numbone || !m3d->bone || !m3d->vertex) {
         return;
@@ -713,7 +703,7 @@ void M3DImporter::populateMesh(const M3DWrapper &m3d, aiMesh *pMesh, std::vector
     ai_assert(vertexids != nullptr);
     ai_assert(m3d);
 
-    ASSIMP_LOG_DEBUG_F("M3D: populateMesh numvertices ", vertices->size(), " numfaces ", faces->size(),
+    ASSIMP_LOG_DEBUG("M3D: populateMesh numvertices ", vertices->size(), " numfaces ", faces->size(),
             " numnormals ", normals->size(), " numtexcoord ", texcoords->size(), " numbones ", m3d->numbone);
 
     if (vertices->size() && faces->size()) {
diff --git a/code/AssetLib/M3D/M3DWrapper.h b/code/AssetLib/M3D/M3DWrapper.h
index 5c370e607..782e908d2 100644
--- a/code/AssetLib/M3D/M3DWrapper.h
+++ b/code/AssetLib/M3D/M3DWrapper.h
@@ -54,7 +54,6 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Assimp specific M3D configuration. Comment out these defines to remove functionality
 //#define ASSIMP_USE_M3D_READFILECB
-//#define M3D_ASCII
 
 #include "m3d.h"
 
diff --git a/code/AssetLib/M3D/m3d.h b/code/AssetLib/M3D/m3d.h
index dfc30aec3..68265959e 100644
--- a/code/AssetLib/M3D/m3d.h
+++ b/code/AssetLib/M3D/m3d.h
@@ -231,14 +231,9 @@ enum {
 typedef struct {
     uint8_t format;
     uint8_t id;
-#ifdef M3D_ASCII
 #define M3D_PROPERTYDEF(f, i, n) \
     { (f), (i), (char *)(n) }
     char *key;
-#else
-#define M3D_PROPERTYDEF(f, i, n) \
-    { (f), (i) }
-#endif
 } m3dpd_t;
 
 /* material property types */
@@ -376,18 +371,11 @@ enum {
 
 #define M3D_CMDMAXARG 8 /* if you increase this, add more arguments to the macro below */
 typedef struct {
-#ifdef M3D_ASCII
 #define M3D_CMDDEF(t, n, p, a, b, c, d, e, f, g, h)                  \
     {                                                                \
         (char *)(n), (p), { (a), (b), (c), (d), (e), (f), (g), (h) } \
     }
     char *key;
-#else
-#define M3D_CMDDEF(t, n, p, a, b, c, d, e, f, g, h)     \
-    {                                                   \
-        (p), { (a), (b), (c), (d), (e), (f), (g), (h) } \
-    }
-#endif
     uint8_t p;
     uint8_t a[M3D_CMDMAXARG];
 } m3dcd_t;
@@ -2059,15 +2047,13 @@ unsigned char *_m3dstbi_zlib_compress(unsigned char *data, int data_len, int *ou
 
 #define M3D_CHUNKMAGIC(m, a, b, c, d) ((m)[0] == (a) && (m)[1] == (b) && (m)[2] == (c) && (m)[3] == (d))
 
-#ifdef M3D_ASCII
 #include <locale.h> /* sprintf and strtod cares about number locale */
 #include <stdio.h> /* get sprintf */
-#endif
 #ifdef M3D_PROFILING
 #include <sys/time.h>
 #endif
 
-#if !defined(M3D_NOIMPORTER) && defined(M3D_ASCII)
+#if !defined(M3D_NOIMPORTER) 
 /* helper functions for the ASCII parser */
 static char *_m3d_findarg(char *s) {
     while (s && *s && *s != ' ' && *s != '\t' && *s != '\r' && *s != '\n')
@@ -2118,7 +2104,7 @@ static char *_m3d_getfloat(char *s, M3D_FLOAT *ret) {
     return _m3d_findarg(e);
 }
 #endif
-#if !defined(M3D_NODUP) && (!defined(M3D_NOIMPORTER) || defined(M3D_ASCII) || defined(M3D_EXPORTER))
+#if !defined(M3D_NODUP) && (!defined(M3D_NOIMPORTER) || defined(M3D_EXPORTER))
 /* helper function to create safe strings */
 char *_m3d_safestr(char *in, int morelines) {
     char *out, *o, *i = in;
@@ -2426,21 +2412,17 @@ m3d_t *m3d_load(unsigned char *data, m3dread_t readfilecb, m3dfree_t freecb, m3d
 #ifndef M3D_NOWEIGHTS
     m3ds_t *sk;
 #endif
-#ifdef M3D_ASCII
     m3ds_t s;
     M3D_INDEX bi[M3D_BONEMAXLEVEL + 1], level;
     const char *ol;
     char *ptr, *pe, *fn;
-#endif
 #ifdef M3D_PROFILING
     struct timeval tv0, tv1, tvd;
     gettimeofday(&tv0, NULL);
 #endif
 
     if (!data || (!M3D_CHUNKMAGIC(data, '3', 'D', 'M', 'O')
-#ifdef M3D_ASCII
                          && !M3D_CHUNKMAGIC(data, '3', 'd', 'm', 'o')
-#endif
                                  ))
         return NULL;
     model = (m3d_t *)M3D_MALLOC(sizeof(m3d_t));
@@ -2457,7 +2439,6 @@ m3d_t *m3d_load(unsigned char *data, m3dread_t readfilecb, m3dfree_t freecb, m3d
         model->texture = mtllib->texture;
         model->flags |= M3D_FLG_MTLLIB;
     }
-#ifdef M3D_ASCII
     /* ASCII variant? */
     if (M3D_CHUNKMAGIC(data, '3', 'd', 'm', 'o')) {
         model->errcode = M3D_ERR_BADFILE;
@@ -3034,7 +3015,6 @@ m3d_t *m3d_load(unsigned char *data, m3dread_t readfilecb, m3dfree_t freecb, m3d
         setlocale(LC_NUMERIC, ol);
         goto postprocess;
     }
-#endif
     /* Binary variant */
     if (!M3D_CHUNKMAGIC(data + 8, 'H', 'E', 'A', 'D')) {
         buff = (unsigned char *)stbi_zlib_decode_malloc_guesssize_headerflag((const char *)data + 8, ((m3dchunk_t *)data)->length - 8,
@@ -3698,9 +3678,7 @@ m3d_t *m3d_load(unsigned char *data, m3dread_t readfilecb, m3dfree_t freecb, m3d
         }
     }
     /* calculate normals, normalize skin weights, create bone/vertex cross-references and calculate transform matrices */
-#ifdef M3D_ASCII
 postprocess:
-#endif
     if (model) {
         M3D_LOG("Post-process");
 #ifdef M3D_PROFILING
@@ -3989,7 +3967,6 @@ void m3d_free(m3d_t *model) {
     unsigned int i, j;
 
     if (!model) return;
-#ifdef M3D_ASCII
     /* if model imported from ASCII, we have to free all strings as well */
     if (model->flags & M3D_FLG_FREESTR) {
         if (model->name) M3D_FREE(model->name);
@@ -4047,7 +4024,6 @@ void m3d_free(m3d_t *model) {
         if (model->preview.data)
             M3D_FREE(model->preview.data);
     }
-#endif
     if (model->flags & M3D_FLG_FREERAW) M3D_FREE(model->raw);
 
     if (model->tmap) M3D_FREE(model->tmap);
@@ -4315,7 +4291,6 @@ static void _m3d_round(int quality, m3dv_t *src, m3dv_t *dst) {
     if (dst->w == (M3D_FLOAT)-0.0) dst->w = (M3D_FLOAT)0.0;
 }
 
-#ifdef M3D_ASCII
 /* add a bone to ascii output */
 static char *_m3d_prtbone(char *ptr, m3db_t *bone, M3D_INDEX numbone, M3D_INDEX parent, uint32_t level, M3D_INDEX *vrtxidx) {
     uint32_t i, j;
@@ -4334,16 +4309,13 @@ static char *_m3d_prtbone(char *ptr, m3db_t *bone, M3D_INDEX numbone, M3D_INDEX
     }
     return ptr;
 }
-#endif
 
 /**
  * Function to encode an in-memory model into on storage Model 3D format
  */
 unsigned char *m3d_save(m3d_t *model, int quality, int flags, unsigned int *size) {
-#ifdef M3D_ASCII
     const char *ol;
     char *ptr;
-#endif
     char vc_s, vi_s, si_s, ci_s, ti_s, bi_s, nb_s, sk_s, fc_s, hi_s, fi_s;
     char *sn = NULL, *sl = NULL, *sa = NULL, *sd = NULL;
     unsigned char *out = NULL, *z = NULL, weights[M3D_NUMBONE], *norm = NULL;
@@ -4369,9 +4341,7 @@ unsigned char *m3d_save(m3d_t *model, int quality, int flags, unsigned int *size
         return NULL;
     }
     model->errcode = M3D_SUCCESS;
-#ifdef M3D_ASCII
     if (flags & M3D_EXP_ASCII) quality = M3D_EXP_DOUBLE;
-#endif
     vrtxidx = (M3D_INDEX *)M3D_MALLOC(model->numvertex * sizeof(M3D_INDEX));
     if (!vrtxidx) goto memerr;
     memset(vrtxidx, 255, model->numvertex * sizeof(M3D_INDEX));
@@ -4800,7 +4770,6 @@ unsigned char *m3d_save(m3d_t *model, int quality, int flags, unsigned int *size
     }
 
     M3D_LOG("Serializing model");
-#ifdef M3D_ASCII
     if (flags & M3D_EXP_ASCII) {
         /* use CRLF to make model creators on Win happy... */
         sd = _m3d_safestr(model->desc, 1);
@@ -5073,7 +5042,7 @@ unsigned char *m3d_save(m3d_t *model, int quality, int flags, unsigned int *size
             ptr += sprintf(ptr, "\r\n");
         }
         /* mathematical shapes face */
-        if (model->numshape !(flags & M3D_EXP_NOFACE)) {
+        if (model->numshape && (!(flags & M3D_EXP_NOFACE))) {
             for (j = 0; j < model->numshape; j++) {
                 sn = _m3d_safestr(model->shape[j].name, 0);
                 if (!sn) {
@@ -5287,7 +5256,6 @@ unsigned char *m3d_save(m3d_t *model, int quality, int flags, unsigned int *size
         if (!out) goto memerr;
         out[len] = 0;
     } else
-#endif
     {
         /* stricly only use LF (newline) in binary */
         sd = _m3d_safestr(model->desc, 3);
diff --git a/code/AssetLib/MD2/MD2Loader.cpp b/code/AssetLib/MD2/MD2Loader.cpp
index 9ccbcdfca..b7bf24ef7 100644
--- a/code/AssetLib/MD2/MD2Loader.cpp
+++ b/code/AssetLib/MD2/MD2Loader.cpp
@@ -53,6 +53,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/IOSystem.hpp>
 #include <assimp/scene.h>
 #include <assimp/importerdesc.h>
+#include <assimp/StringUtils.h>
 
 #include <memory>
 
@@ -148,46 +149,39 @@ void MD2Importer::ValidateHeader( )
     if (m_pcHeader->magic != AI_MD2_MAGIC_NUMBER_BE &&
         m_pcHeader->magic != AI_MD2_MAGIC_NUMBER_LE)
     {
-        char szBuffer[5];
-        szBuffer[0] = ((char*)&m_pcHeader->magic)[0];
-        szBuffer[1] = ((char*)&m_pcHeader->magic)[1];
-        szBuffer[2] = ((char*)&m_pcHeader->magic)[2];
-        szBuffer[3] = ((char*)&m_pcHeader->magic)[3];
-        szBuffer[4] = '\0';
-
-        throw DeadlyImportError("Invalid MD2 magic word: should be IDP2, the "
-            "magic word found is " + std::string(szBuffer));
+        throw DeadlyImportError("Invalid MD2 magic word: expected IDP2, found ",
+                                ai_str_toprintable((char *)&m_pcHeader->magic, 4));
     }
 
     // check file format version
     if (m_pcHeader->version != 8)
-        ASSIMP_LOG_WARN( "Unsupported md2 file version. Continuing happily ...");
+        ASSIMP_LOG_WARN( "Unsupported MD2 file version. Continuing happily ...");
 
     // check some values whether they are valid
     if (0 == m_pcHeader->numFrames)
-        throw DeadlyImportError( "Invalid md2 file: NUM_FRAMES is 0");
+        throw DeadlyImportError( "Invalid MD2 file: NUM_FRAMES is 0");
 
     if (m_pcHeader->offsetEnd > (uint32_t)fileSize)
-        throw DeadlyImportError( "Invalid md2 file: File is too small");
+        throw DeadlyImportError( "Invalid MD2 file: File is too small");
 
     if (m_pcHeader->numSkins > AI_MAX_ALLOC(MD2::Skin)) {
-        throw DeadlyImportError("Invalid MD2 header: too many skins, would overflow");
+        throw DeadlyImportError("Invalid MD2 header: Too many skins, would overflow");
     }
 
     if (m_pcHeader->numVertices > AI_MAX_ALLOC(MD2::Vertex)) {
-        throw DeadlyImportError("Invalid MD2 header: too many vertices, would overflow");
+        throw DeadlyImportError("Invalid MD2 header: Too many vertices, would overflow");
     }
 
     if (m_pcHeader->numTexCoords > AI_MAX_ALLOC(MD2::TexCoord)) {
-        throw DeadlyImportError("Invalid MD2 header: too many texcoords, would overflow");
+        throw DeadlyImportError("Invalid MD2 header: Too many texcoords, would overflow");
     }
 
     if (m_pcHeader->numTriangles > AI_MAX_ALLOC(MD2::Triangle)) {
-        throw DeadlyImportError("Invalid MD2 header: too many triangles, would overflow");
+        throw DeadlyImportError("Invalid MD2 header: Too many triangles, would overflow");
     }
 
     if (m_pcHeader->numFrames > AI_MAX_ALLOC(MD2::Frame)) {
-        throw DeadlyImportError("Invalid MD2 header: too many frames, would overflow");
+        throw DeadlyImportError("Invalid MD2 header: Too many frames, would overflow");
     }
 
     // -1 because Frame already contains one
@@ -199,7 +193,7 @@ void MD2Importer::ValidateHeader( )
         m_pcHeader->offsetFrames    + m_pcHeader->numFrames * frameSize                 >= fileSize ||
         m_pcHeader->offsetEnd           > fileSize)
     {
-        throw DeadlyImportError("Invalid MD2 header: some offsets are outside the file");
+        throw DeadlyImportError("Invalid MD2 header: Some offsets are outside the file");
     }
 
     if (m_pcHeader->numSkins > AI_MD2_MAX_SKINS)
@@ -210,7 +204,7 @@ void MD2Importer::ValidateHeader( )
         ASSIMP_LOG_WARN("The model contains more vertices than Quake 2 supports");
 
     if (m_pcHeader->numFrames <= configFrameID )
-        throw DeadlyImportError("The requested frame is not existing the file");
+        throw DeadlyImportError("MD2: The requested frame (", configFrameID, ") does not exist in the file");
 }
 
 // ------------------------------------------------------------------------------------------------
@@ -433,10 +427,6 @@ void MD2Importer::InternReadFile( const std::string& pFile,
             aiVector3D& vNormal = pcMesh->mNormals[iCurrent];
             LookupNormalIndex(pcVerts[iIndex].lightNormalIndex,vNormal);
 
-            // flip z and y to become right-handed
-            std::swap((float&)vNormal.z,(float&)vNormal.y);
-            std::swap((float&)vec.z,(float&)vec.y);
-
             if (m_pcHeader->numTexCoords)   {
                 // validate texture coordinates
                 iIndex = pcTriangles[i].textureIndices[c];
@@ -454,7 +444,15 @@ void MD2Importer::InternReadFile( const std::string& pFile,
             }
             pScene->mMeshes[0]->mFaces[i].mIndices[c] = iCurrent;
         }
+        // flip the face order
+        std::swap( pScene->mMeshes[0]->mFaces[i].mIndices[0], pScene->mMeshes[0]->mFaces[i].mIndices[2] );
     }
+    // Now rotate the whole scene 90 degrees around the x axis to convert to internal coordinate system
+    pScene->mRootNode->mTransformation = aiMatrix4x4(
+            1.f, 0.f, 0.f, 0.f,
+            0.f, 0.f, 1.f, 0.f,
+            0.f, -1.f, 0.f, 0.f,
+            0.f, 0.f, 0.f, 1.f);
 }
 
 #endif // !! ASSIMP_BUILD_NO_MD2_IMPORTER
diff --git a/code/AssetLib/MD2/MD2NormalTable.h b/code/AssetLib/MD2/MD2NormalTable.h
index 3eff0d666..b2330d862 100644
--- a/code/AssetLib/MD2/MD2NormalTable.h
+++ b/code/AssetLib/MD2/MD2NormalTable.h
@@ -51,7 +51,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define AI_MDL_NORMALTABLE_H_INC
 
 
-float g_avNormals[162][3] = {
+const float g_avNormals[162][3] = {
 { -0.525731f,  0.000000f,  0.850651f },
 { -0.442863f,  0.238856f,  0.864188f },
 { -0.295242f,  0.000000f,  0.955423f },
diff --git a/code/AssetLib/MD3/MD3Loader.cpp b/code/AssetLib/MD3/MD3Loader.cpp
index 53a0eea41..abaabe47f 100644
--- a/code/AssetLib/MD3/MD3Loader.cpp
+++ b/code/AssetLib/MD3/MD3Loader.cpp
@@ -101,7 +101,7 @@ Q3Shader::BlendFunc StringToBlendFunc(const std::string &m) {
     if (m == "GL_ONE_MINUS_DST_COLOR") {
         return Q3Shader::BLEND_GL_ONE_MINUS_DST_COLOR;
     }
-    ASSIMP_LOG_ERROR("Q3Shader: Unknown blend function: " + m);
+    ASSIMP_LOG_ERROR("Q3Shader: Unknown blend function: ", m);
     return Q3Shader::BLEND_NONE;
 }
 
@@ -112,7 +112,7 @@ bool Q3Shader::LoadShader(ShaderData &fill, const std::string &pFile, IOSystem *
     if (!file.get())
         return false; // if we can't access the file, don't worry and return
 
-    ASSIMP_LOG_INFO_F("Loading Quake3 shader file ", pFile);
+    ASSIMP_LOG_INFO("Loading Quake3 shader file ", pFile);
 
     // read file in memory
     const size_t s = file->FileSize();
@@ -226,7 +226,7 @@ bool Q3Shader::LoadSkin(SkinData &fill, const std::string &pFile, IOSystem *io)
     if (!file.get())
         return false; // if we can't access the file, don't worry and return
 
-    ASSIMP_LOG_INFO("Loading Quake3 skin file " + pFile);
+    ASSIMP_LOG_INFO("Loading Quake3 skin file ", pFile);
 
     // read file in memory
     const size_t s = file->FileSize();
@@ -706,7 +706,7 @@ void MD3Importer::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
     }
     filename = mFile.substr(s), path = mFile.substr(0, s);
     for (std::string::iterator it = filename.begin(); it != filename.end(); ++it) {
-        *it = static_cast<char>(tolower(*it));
+        *it = static_cast<char>(tolower(static_cast<unsigned char>(*it)));
     }
 
     // Load multi-part model file, if necessary
@@ -857,7 +857,7 @@ void MD3Importer::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 
         if (it != skins.textures.end()) {
             texture_name = &*(_texture_name = (*it).second).begin();
-            ASSIMP_LOG_VERBOSE_DEBUG_F("MD3: Assigning skin texture ", (*it).second, " to surface ", pcSurfaces->NAME);
+            ASSIMP_LOG_VERBOSE_DEBUG("MD3: Assigning skin texture ", (*it).second, " to surface ", pcSurfaces->NAME);
             (*it).resolved = true; // mark entry as resolved
         }
 
@@ -891,9 +891,9 @@ void MD3Importer::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
             if (dit != shaders.blocks.end()) {
                 // We made it!
                 shader = &*dit;
-                ASSIMP_LOG_INFO("Found shader record for " + without_ext);
+                ASSIMP_LOG_INFO("Found shader record for ", without_ext);
             } else {
-                ASSIMP_LOG_WARN("Unable to find shader record for " + without_ext);
+                ASSIMP_LOG_WARN("Unable to find shader record for ", without_ext);
             }
         }
 
@@ -1011,7 +1011,7 @@ void MD3Importer::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
     if (!DefaultLogger::isNullLogger()) {
         for (std::list<Q3Shader::SkinData::TextureEntry>::const_iterator it = skins.textures.begin(); it != skins.textures.end(); ++it) {
             if (!(*it).resolved) {
-                ASSIMP_LOG_ERROR_F("MD3: Failed to match skin ", (*it).first, " to surface ", (*it).second);
+                ASSIMP_LOG_ERROR("MD3: Failed to match skin ", (*it).first, " to surface ", (*it).second);
             }
         }
     }
diff --git a/code/AssetLib/MD5/MD5Loader.cpp b/code/AssetLib/MD5/MD5Loader.cpp
index b99638cd2..0d9c77b71 100644
--- a/code/AssetLib/MD5/MD5Loader.cpp
+++ b/code/AssetLib/MD5/MD5Loader.cpp
@@ -345,7 +345,7 @@ void MD5Importer::LoadMD5MeshFile() {
 
     // Check whether we can read from the file
     if (file.get() == nullptr || !file->FileSize()) {
-        ASSIMP_LOG_WARN("Failed to access MD5MESH file: " + filename);
+        ASSIMP_LOG_WARN("Failed to access MD5MESH file: ", filename);
         return;
     }
     mHadMD5Mesh = true;
@@ -567,7 +567,7 @@ void MD5Importer::LoadMD5AnimFile() {
 
     // Check whether we can read from the file
     if (!file.get() || !file->FileSize()) {
-        ASSIMP_LOG_WARN("Failed to read MD5ANIM file: " + pFile);
+        ASSIMP_LOG_WARN("Failed to read MD5ANIM file: ", pFile);
         return;
     }
 
diff --git a/code/AssetLib/MDC/MDCLoader.cpp b/code/AssetLib/MDC/MDCLoader.cpp
index 17a349768..8f089bbd8 100644
--- a/code/AssetLib/MDC/MDCLoader.cpp
+++ b/code/AssetLib/MDC/MDCLoader.cpp
@@ -53,6 +53,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/DefaultLogger.hpp>
 #include <assimp/IOSystem.hpp>
 #include <assimp/Importer.hpp>
+#include <assimp/StringUtils.h>
 
 #include <memory>
 
@@ -143,16 +144,8 @@ void MDCImporter::ValidateHeader() {
 
     if (pcHeader->ulIdent != AI_MDC_MAGIC_NUMBER_BE &&
             pcHeader->ulIdent != AI_MDC_MAGIC_NUMBER_LE) {
-        char szBuffer[5];
-        szBuffer[0] = ((char *)&pcHeader->ulIdent)[0];
-        szBuffer[1] = ((char *)&pcHeader->ulIdent)[1];
-        szBuffer[2] = ((char *)&pcHeader->ulIdent)[2];
-        szBuffer[3] = ((char *)&pcHeader->ulIdent)[3];
-        szBuffer[4] = '\0';
-
-        throw DeadlyImportError("Invalid MDC magic word: should be IDPC, the "
-                                "magic word found is " +
-                                std::string(szBuffer));
+        throw DeadlyImportError("Invalid MDC magic word: expected IDPC, found ",
+                                ai_str_toprintable((char *)&pcHeader->ulIdent, 4));
     }
 
     if (pcHeader->ulVersion != AI_MDC_VERSION) {
@@ -465,6 +458,13 @@ void MDCImporter::InternReadFile(
             pcMat->AddProperty(&path, AI_MATKEY_TEXTURE_DIFFUSE(0));
         }
     }
+
+    // Now rotate the whole scene 90 degrees around the x axis to convert to internal coordinate system
+    pScene->mRootNode->mTransformation = aiMatrix4x4(
+            1.f, 0.f, 0.f, 0.f,
+            0.f, 0.f, 1.f, 0.f,
+            0.f, -1.f, 0.f, 0.f,
+            0.f, 0.f, 0.f, 1.f);
 }
 
 #endif // !! ASSIMP_BUILD_NO_MDC_IMPORTER
diff --git a/code/AssetLib/MDC/MDCNormalTable.h b/code/AssetLib/MDC/MDCNormalTable.h
index f47e97f33..c96eba7bd 100644
--- a/code/AssetLib/MDC/MDCNormalTable.h
+++ b/code/AssetLib/MDC/MDCNormalTable.h
@@ -36,7 +36,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define MDC_NORMAL_TABLE_INCLUDED
 
 /* mdc decoding normal table */
-float mdcNormals[ 256 ][ 3 ] =
+const float mdcNormals[ 256 ][ 3 ] =
 {
     { 1.000000f, 0.000000f, 0.000000f },
     { 0.980785f, 0.195090f, 0.000000f },
diff --git a/code/AssetLib/MDL/HalfLife/HL1MDLLoader.cpp b/code/AssetLib/MDL/HalfLife/HL1MDLLoader.cpp
index 4df0d0d1d..e6576b344 100644
--- a/code/AssetLib/MDL/HalfLife/HL1MDLLoader.cpp
+++ b/code/AssetLib/MDL/HalfLife/HL1MDLLoader.cpp
@@ -57,6 +57,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <iomanip>
 #include <sstream>
+#include <map>
 
 #ifdef MDL_HALFLIFE_LOG_WARN_HEADER
 #undef MDL_HALFLIFE_LOG_WARN_HEADER
@@ -868,7 +869,7 @@ void HL1MDLLoader::read_meshes() {
                         scene_mesh->mNormals[v] = bind_pose_normals[pTrivert->normindex];
                         scene_mesh->mTextureCoords[0][v] = aiVector3D(
                                 pTrivert->s * texcoords_s_scale,
-                                pTrivert->t * texcoords_t_scale, 0);
+                                pTrivert->t * -texcoords_t_scale, 0);
                     }
 
                     // Add face and indices.
@@ -879,9 +880,9 @@ void HL1MDLLoader::read_meshes() {
                         aiFace *face = &scene_mesh->mFaces[f];
                         face->mNumIndices = 3;
                         face->mIndices = new unsigned int[3];
-                        face->mIndices[0] = mesh_faces[f].v0;
+                        face->mIndices[0] = mesh_faces[f].v2;
                         face->mIndices[1] = mesh_faces[f].v1;
-                        face->mIndices[2] = mesh_faces[f].v2;
+                        face->mIndices[2] = mesh_faces[f].v0;
                     }
 
                     // Add mesh bones.
@@ -1342,7 +1343,7 @@ bool HL1MDLLoader::get_num_blend_controllers(const int num_blend_animations, int
             return true;
         default:
             num_blend_controllers = 0;
-            ASSIMP_LOG_WARN(MDL_HALFLIFE_LOG_HEADER "Unsupported number of blend animations (" + std::to_string(num_blend_animations) + ")");
+            ASSIMP_LOG_WARN(MDL_HALFLIFE_LOG_HEADER "Unsupported number of blend animations (", num_blend_animations, ")");
             return false;
     }
 }
diff --git a/code/AssetLib/MDL/HalfLife/UniqueNameGenerator.cpp b/code/AssetLib/MDL/HalfLife/UniqueNameGenerator.cpp
index 72081ea73..dde81454b 100644
--- a/code/AssetLib/MDL/HalfLife/UniqueNameGenerator.cpp
+++ b/code/AssetLib/MDL/HalfLife/UniqueNameGenerator.cpp
@@ -95,7 +95,7 @@ void UniqueNameGenerator::make_unique(std::vector<std::string> &names) {
     auto generate_unique_name = [&](const std::string &base_name) -> std::string {
         auto *duplicate_info = &names_to_duplicates[base_name];
 
-        std::string new_name = "";
+        std::string new_name;
 
         bool found_identical_name;
         bool tried_with_base_name_only = false;
diff --git a/code/AssetLib/MDL/MDLLoader.cpp b/code/AssetLib/MDL/MDLLoader.cpp
index a4286a716..51d76e740 100644
--- a/code/AssetLib/MDL/MDLLoader.cpp
+++ b/code/AssetLib/MDL/MDLLoader.cpp
@@ -199,6 +199,7 @@ void MDLImporter::InternReadFile(const std::string &pFile,
         const uint32_t iMagicWord = *((uint32_t *)mBuffer);
 
         // Determine the file subtype and call the appropriate member function
+        bool is_half_life = false;
 
         // Original Quake1 format
         if (AI_MDL_MAGIC_NUMBER_BE == iMagicWord || AI_MDL_MAGIC_NUMBER_LE == iMagicWord) {
@@ -240,6 +241,7 @@ void MDLImporter::InternReadFile(const std::string &pFile,
         else if (AI_MDL_MAGIC_NUMBER_BE_HL2a == iMagicWord || AI_MDL_MAGIC_NUMBER_LE_HL2a == iMagicWord ||
                  AI_MDL_MAGIC_NUMBER_BE_HL2b == iMagicWord || AI_MDL_MAGIC_NUMBER_LE_HL2b == iMagicWord) {
             iGSFileVersion = 0;
+            is_half_life = true;
 
             HalfLife::HalfLifeMDLBaseHeader *pHeader = (HalfLife::HalfLifeMDLBaseHeader *)mBuffer;
             if (pHeader->version == AI_MDL_HL1_VERSION) {
@@ -252,12 +254,22 @@ void MDLImporter::InternReadFile(const std::string &pFile,
         } else {
             // print the magic word to the log file
             throw DeadlyImportError("Unknown MDL subformat ", pFile,
-                                    ". Magic word (", std::string((char *)&iMagicWord, 4), ") is not known");
+                                    ". Magic word (", ai_str_toprintable((const char *)&iMagicWord, sizeof(iMagicWord)), ") is not known");
         }
 
-        // Now rotate the whole scene 90 degrees around the x axis to convert to internal coordinate system
-        pScene->mRootNode->mTransformation = aiMatrix4x4(1.f, 0.f, 0.f, 0.f,
-                0.f, 0.f, 1.f, 0.f, 0.f, -1.f, 0.f, 0.f, 0.f, 0.f, 0.f, 1.f);
+        if (is_half_life){
+            // Now rotate the whole scene 90 degrees around the z and x axes to convert to internal coordinate system
+            pScene->mRootNode->mTransformation = aiMatrix4x4(
+                    0.f, -1.f, 0.f, 0.f,
+                    0.f, 0.f, 1.f, 0.f,
+                    -1.f, 0.f, 0.f, 0.f,
+                    0.f, 0.f, 0.f, 1.f);
+        }
+        else {
+            // Now rotate the whole scene 90 degrees around the x axis to convert to internal coordinate system
+            pScene->mRootNode->mTransformation = aiMatrix4x4(1.f, 0.f, 0.f, 0.f,
+                    0.f, 0.f, 1.f, 0.f, 0.f, -1.f, 0.f, 0.f, 0.f, 0.f, 0.f, 1.f);
+        }
 
         DeleteBufferAndCleanup();
     } catch (...) {
diff --git a/code/AssetLib/MMD/MMDImporter.cpp b/code/AssetLib/MMD/MMDImporter.cpp
index e4ecc1445..2895c3879 100644
--- a/code/AssetLib/MMD/MMDImporter.cpp
+++ b/code/AssetLib/MMD/MMDImporter.cpp
@@ -75,7 +75,7 @@ using namespace std;
 //  Default constructor
 MMDImporter::MMDImporter() :
         m_Buffer(),
-        m_strAbsPath("") {
+        m_strAbsPath() {
     DefaultIOSystem io;
     m_strAbsPath = io.getOsSeparator();
 }
diff --git a/code/AssetLib/MMD/MMDPmxParser.cpp b/code/AssetLib/MMD/MMDPmxParser.cpp
index 320182c3d..d57dc169a 100644
--- a/code/AssetLib/MMD/MMDPmxParser.cpp
+++ b/code/AssetLib/MMD/MMDPmxParser.cpp
@@ -91,7 +91,7 @@ namespace pmx
 		std::vector<char> buffer;
 		if (size == 0)
 		{
-			return std::string("");
+			return std::string();
 		}
 		buffer.reserve(size);
 		stream->read((char*) buffer.data(), size);
@@ -478,8 +478,7 @@ namespace pmx
 
     void PmxSoftBody::Read(std::istream * /*stream*/, PmxSetting * /*setting*/)
 	{
-		std::cerr << "Not Implemented Exception" << std::endl;
-        throw DeadlyImportError("MMD: Not Implemented Exception");
+        throw DeadlyImportError("MMD: Soft Body support is not implemented.");
     }
 
 	void PmxModel::Init()
@@ -516,15 +515,13 @@ namespace pmx
 		char magic[4];
 		stream->read((char*) magic, sizeof(char) * 4);
 		if (magic[0] != 0x50 || magic[1] != 0x4d || magic[2] != 0x58 || magic[3] != 0x20)
-		{
-			std::cerr << "invalid magic number." << std::endl;
-      throw DeadlyImportError("MMD: invalid magic number.");
+        {
+      throw DeadlyImportError("MMD: Invalid magic number.");
     }
 		stream->read((char*) &version, sizeof(float));
 		if (version != 2.0f && version != 2.1f)
 		{
-			std::cerr << "this is not ver2.0 or ver2.1 but " << version << "." << std::endl;
-            throw DeadlyImportError("MMD: this is not ver2.0 or ver2.1 but ", ai_to_string(version));
+            throw DeadlyImportError("MMD: Unsupported version (must be 2.0 or 2.1): ", ai_to_string(version));
     }
 		this->setting.Read(stream);
 
diff --git a/code/AssetLib/MS3D/MS3DLoader.cpp b/code/AssetLib/MS3D/MS3DLoader.cpp
index 192bcbe41..e4057a43a 100644
--- a/code/AssetLib/MS3D/MS3DLoader.cpp
+++ b/code/AssetLib/MS3D/MS3DLoader.cpp
@@ -215,7 +215,12 @@ void MS3DImporter :: CollectChildJoints(const std::vector<TempJoint>& joints, ai
 void MS3DImporter::InternReadFile( const std::string& pFile,
     aiScene* pScene, IOSystem* pIOHandler)
 {
-    StreamReaderLE stream(pIOHandler->Open(pFile,"rb"));
+
+    auto file = pIOHandler->Open(pFile, "rb");
+    if (!file)
+        throw DeadlyImportError("MS3D: Could not open ", pFile);
+
+    StreamReaderLE stream(file);
 
     // CanRead() should have done this already
     char head[10];
@@ -382,7 +387,7 @@ void MS3DImporter::InternReadFile( const std::string& pFile,
                 }
 
                 const std::string& s = std::string(reinterpret_cast<char*>(stream.GetPtr()),len);
-                ASSIMP_LOG_DEBUG_F("MS3D: Model comment: ", s);
+                ASSIMP_LOG_DEBUG("MS3D: Model comment: ", s);
             }
 
             if(stream.GetRemainingSize() > 4 && inrange((stream >> subversion,subversion),1u,3u)) {
diff --git a/code/AssetLib/NDO/NDOLoader.cpp b/code/AssetLib/NDO/NDOLoader.cpp
index 77fe3e36c..0abc09dc8 100644
--- a/code/AssetLib/NDO/NDOLoader.cpp
+++ b/code/AssetLib/NDO/NDOLoader.cpp
@@ -116,7 +116,13 @@ void NDOImporter::SetupProperties(const Importer* /*pImp*/)
 void NDOImporter::InternReadFile( const std::string& pFile,
     aiScene* pScene, IOSystem* pIOHandler)
 {
-    StreamReaderBE reader(pIOHandler->Open( pFile, "rb"));
+
+    auto file = pIOHandler->Open( pFile, "rb");
+    if (!file) {
+        throw DeadlyImportError("Nendo: Could not open ", pFile);
+    }
+
+    StreamReaderBE reader(file);
 
     // first 9 bytes are nendo file format ("nendo 1.n")
     const char* head = (const char*)reader.GetPtr();
@@ -141,7 +147,7 @@ void NDOImporter::InternReadFile( const std::string& pFile,
         ASSIMP_LOG_INFO("NDO file format is 1.2");
     }
     else {
-        ASSIMP_LOG_WARN_F( "Unrecognized nendo file format version, continuing happily ... :", (head+6));
+        ASSIMP_LOG_WARN( "Unrecognized nendo file format version, continuing happily ... :", (head+6));
     }
 
     reader.IncPtr(2); /* skip flags */
diff --git a/code/AssetLib/NFF/NFFLoader.cpp b/code/AssetLib/NFF/NFFLoader.cpp
index 11cce0990..15f46b5e6 100644
--- a/code/AssetLib/NFF/NFFLoader.cpp
+++ b/code/AssetLib/NFF/NFFLoader.cpp
@@ -132,7 +132,7 @@ void NFFImporter::LoadNFF2MaterialTable(std::vector<ShadingInfo> &output,
 
     // Check whether we can read from the file
     if (!file.get()) {
-        ASSIMP_LOG_ERROR("NFF2: Unable to open material library " + path + ".");
+        ASSIMP_LOG_ERROR("NFF2: Unable to open material library ", path, ".");
         return;
     }
 
@@ -150,7 +150,7 @@ void NFFImporter::LoadNFF2MaterialTable(std::vector<ShadingInfo> &output,
 
     // The file should start with the magic sequence "mat"
     if (!TokenMatch(buffer, "mat", 3)) {
-        ASSIMP_LOG_ERROR_F("NFF2: Not a valid material library ", path, ".");
+        ASSIMP_LOG_ERROR("NFF2: Not a valid material library ", path, ".");
         return;
     }
 
@@ -164,7 +164,7 @@ void NFFImporter::LoadNFF2MaterialTable(std::vector<ShadingInfo> &output,
 
         // 'version' defines the version of the file format
         if (TokenMatch(sz, "version", 7)) {
-            ASSIMP_LOG_INFO_F("NFF (Sense8) material library file format: ", std::string(sz));
+            ASSIMP_LOG_INFO("NFF (Sense8) material library file format: ", std::string(sz));
         }
         // 'matdef' starts a new material in the file
         else if (TokenMatch(sz, "matdef", 6)) {
@@ -177,7 +177,7 @@ void NFFImporter::LoadNFF2MaterialTable(std::vector<ShadingInfo> &output,
             // check whether we have an active material at the moment
             if (!IsLineEnd(*sz)) {
                 if (!curShader) {
-                    ASSIMP_LOG_ERROR_F("NFF2 material library: Found element ", sz, "but there is no active material");
+                    ASSIMP_LOG_ERROR("NFF2 material library: Found element ", sz, "but there is no active material");
                     continue;
                 }
             } else
@@ -277,7 +277,7 @@ void NFFImporter::InternReadFile(const std::string &pFile,
         while (GetNextLine(buffer, line)) {
             SkipSpaces(line, &sz);
             if (TokenMatch(sz, "version", 7)) {
-                ASSIMP_LOG_INFO_F("NFF (Sense8) file format: ", sz);
+                ASSIMP_LOG_INFO("NFF (Sense8) file format: ", sz);
             } else if (TokenMatch(sz, "viewpos", 7)) {
                 AI_NFF_PARSE_TRIPLE(camPos);
                 hasCam = true;
diff --git a/code/AssetLib/Obj/ObjFileParser.cpp b/code/AssetLib/Obj/ObjFileParser.cpp
index a8039ae23..767805c10 100644
--- a/code/AssetLib/Obj/ObjFileParser.cpp
+++ b/code/AssetLib/Obj/ObjFileParser.cpp
@@ -556,7 +556,7 @@ void ObjFileParser::getMaterialDesc() {
             // This may be the case if the material library is missing. We don't want to lose all
             // materials if that happens, so create a new named material instead of discarding it
             // completely.
-            ASSIMP_LOG_ERROR("OBJ: failed to locate material " + strName + ", creating new material");
+            ASSIMP_LOG_ERROR("OBJ: failed to locate material ", strName, ", creating new material");
             m_pModel->m_pCurrentMaterial = new ObjFile::Material();
             m_pModel->m_pCurrentMaterial->MaterialName.Set(strName);
             m_pModel->m_MaterialLib.push_back(strName);
@@ -620,12 +620,12 @@ void ObjFileParser::getMaterialLib() {
 
     IOStream *pFile = m_pIO->Open(absName);
     if (nullptr == pFile) {
-        ASSIMP_LOG_ERROR("OBJ: Unable to locate material file " + strMatName);
+        ASSIMP_LOG_ERROR("OBJ: Unable to locate material file ", strMatName);
         std::string strMatFallbackName = m_originalObjFileName.substr(0, m_originalObjFileName.length() - 3) + "mtl";
-        ASSIMP_LOG_INFO("OBJ: Opening fallback material file " + strMatFallbackName);
+        ASSIMP_LOG_INFO("OBJ: Opening fallback material file ", strMatFallbackName);
         pFile = m_pIO->Open(strMatFallbackName);
         if (!pFile) {
-            ASSIMP_LOG_ERROR("OBJ: Unable to locate fallback material file " + strMatFallbackName);
+            ASSIMP_LOG_ERROR("OBJ: Unable to locate fallback material file ", strMatFallbackName);
             m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
             return;
         }
@@ -660,7 +660,7 @@ void ObjFileParser::getNewMaterial() {
     std::map<std::string, ObjFile::Material *>::iterator it = m_pModel->m_MaterialMap.find(strMat);
     if (it == m_pModel->m_MaterialMap.end()) {
         // Show a warning, if material was not found
-        ASSIMP_LOG_WARN("OBJ: Unsupported material requested: " + strMat);
+        ASSIMP_LOG_WARN("OBJ: Unsupported material requested: ", strMat);
         m_pModel->m_pCurrentMaterial = m_pModel->m_pDefaultMaterial;
     } else {
         // Set new material
diff --git a/code/AssetLib/Ogre/OgreBinarySerializer.cpp b/code/AssetLib/Ogre/OgreBinarySerializer.cpp
index 0fc18feb9..1d20799a1 100644
--- a/code/AssetLib/Ogre/OgreBinarySerializer.cpp
+++ b/code/AssetLib/Ogre/OgreBinarySerializer.cpp
@@ -155,7 +155,7 @@ uint16_t OgreBinarySerializer::ReadHeader(bool readLen) {
 
 #if (OGRE_BINARY_SERIALIZER_DEBUG == 1)
     if (id != HEADER_CHUNK_ID) {
-        ASSIMP_LOG_DEBUG(Formatter::format() << (assetMode == AM_Mesh ? MeshHeaderToString(static_cast<MeshChunkId>(id)) : SkeletonHeaderToString(static_cast<SkeletonChunkId>(id))));
+        ASSIMP_LOG_DEBUG((assetMode == AM_Mesh ? MeshHeaderToString(static_cast<MeshChunkId>(id)) : SkeletonHeaderToString(static_cast<SkeletonChunkId>(id))));
     }
 #endif
 
@@ -168,7 +168,7 @@ void OgreBinarySerializer::RollbackHeader() {
 
 void OgreBinarySerializer::SkipBytes(size_t numBytes) {
 #if (OGRE_BINARY_SERIALIZER_DEBUG == 1)
-    ASSIMP_LOG_VERBOSE_DEBUG_F("Skipping ", numBytes, " bytes");
+    ASSIMP_LOG_VERBOSE_DEBUG("Skipping ", numBytes, " bytes");
 #endif
 
     m_reader->IncPtr(numBytes);
@@ -208,7 +208,7 @@ void OgreBinarySerializer::ReadMesh(Mesh *mesh) {
     mesh->hasSkeletalAnimations = Read<bool>();
 
     ASSIMP_LOG_VERBOSE_DEBUG("Reading Mesh");
-    ASSIMP_LOG_VERBOSE_DEBUG_F("  - Skeletal animations: ", mesh->hasSkeletalAnimations ? "true" : "false");
+    ASSIMP_LOG_VERBOSE_DEBUG("  - Skeletal animations: ", mesh->hasSkeletalAnimations ? "true" : "false");
 
     if (!AtEnd()) {
         uint16_t id = ReadHeader();
@@ -364,9 +364,9 @@ void OgreBinarySerializer::ReadSubMesh(Mesh *mesh) {
     submesh->indexData->faceCount = static_cast<uint32_t>(submesh->indexData->count / 3);
     submesh->indexData->is32bit = Read<bool>();
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("Reading SubMesh ", mesh->subMeshes.size());
-    ASSIMP_LOG_VERBOSE_DEBUG_F("  - Material: '", submesh->materialRef, "'");
-    ASSIMP_LOG_VERBOSE_DEBUG_F("  - Uses shared geometry: ", submesh->usesSharedVertexData ? "true" : "false");
+    ASSIMP_LOG_VERBOSE_DEBUG("Reading SubMesh ", mesh->subMeshes.size());
+    ASSIMP_LOG_VERBOSE_DEBUG("  - Material: '", submesh->materialRef, "'");
+    ASSIMP_LOG_VERBOSE_DEBUG("  - Uses shared geometry: ", submesh->usesSharedVertexData ? "true" : "false");
 
     // Index buffer
     if (submesh->indexData->count > 0) {
@@ -374,7 +374,7 @@ void OgreBinarySerializer::ReadSubMesh(Mesh *mesh) {
         uint8_t *indexBuffer = ReadBytes(numBytes);
         submesh->indexData->buffer = MemoryStreamPtr(new Assimp::MemoryIOStream(indexBuffer, numBytes, true));
 
-        ASSIMP_LOG_VERBOSE_DEBUG_F("  - ", submesh->indexData->faceCount,
+        ASSIMP_LOG_VERBOSE_DEBUG("  - ", submesh->indexData->faceCount,
                 " faces from ", submesh->indexData->count, (submesh->indexData->is32bit ? " 32bit" : " 16bit"),
                 " indexes of ", numBytes, " bytes");
     }
@@ -475,7 +475,7 @@ void OgreBinarySerializer::ReadSubMeshNames(Mesh *mesh) {
             }
 
             submesh->name = ReadLine();
-            ASSIMP_LOG_VERBOSE_DEBUG_F("  - SubMesh ", submesh->index, " name '", submesh->name, "'");
+            ASSIMP_LOG_VERBOSE_DEBUG("  - SubMesh ", submesh->index, " name '", submesh->name, "'");
 
             if (!AtEnd())
                 id = ReadHeader();
@@ -488,7 +488,7 @@ void OgreBinarySerializer::ReadSubMeshNames(Mesh *mesh) {
 void OgreBinarySerializer::ReadGeometry(VertexData *dest) {
     dest->count = Read<uint32_t>();
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("  - Reading geometry of ", dest->count, " vertices");
+    ASSIMP_LOG_VERBOSE_DEBUG("  - Reading geometry of ", dest->count, " vertices");
 
     if (!AtEnd()) {
         uint16_t id = ReadHeader();
@@ -536,7 +536,7 @@ void OgreBinarySerializer::ReadGeometryVertexElement(VertexData *dest) {
     element.offset = Read<uint16_t>();
     element.index = Read<uint16_t>();
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("    - Vertex element ", element.SemanticToString(), " of type ",
+    ASSIMP_LOG_VERBOSE_DEBUG("    - Vertex element ", element.SemanticToString(), " of type ",
             element.TypeToString(), " index=", element.index, " source=", element.source);
 
     dest->vertexElements.push_back(element);
@@ -557,7 +557,7 @@ void OgreBinarySerializer::ReadGeometryVertexBuffer(VertexData *dest) {
     uint8_t *vertexBuffer = ReadBytes(numBytes);
     dest->vertexBindings[bindIndex] = MemoryStreamPtr(new Assimp::MemoryIOStream(vertexBuffer, numBytes, true));
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("    - Read vertex buffer for source ", bindIndex, " of ", numBytes, " bytes");
+    ASSIMP_LOG_VERBOSE_DEBUG("    - Read vertex buffer for source ", bindIndex, " of ", numBytes, " bytes");
 }
 
 void OgreBinarySerializer::ReadEdgeList(Mesh * /*mesh*/) {
@@ -777,12 +777,12 @@ bool OgreBinarySerializer::ImportSkeleton(Assimp::IOSystem *pIOHandler, MeshXml
 
 MemoryStreamReaderPtr OgreBinarySerializer::OpenReader(Assimp::IOSystem *pIOHandler, const std::string &filename) {
     if (!EndsWith(filename, ".skeleton", false)) {
-        ASSIMP_LOG_ERROR_F("Imported Mesh is referencing to unsupported '", filename, "' skeleton file.");
+        ASSIMP_LOG_ERROR("Imported Mesh is referencing to unsupported '", filename, "' skeleton file.");
         return MemoryStreamReaderPtr();
     }
 
     if (!pIOHandler->Exists(filename)) {
-        ASSIMP_LOG_ERROR_F("Failed to find skeleton file '", filename, "' that is referenced by imported Mesh.");
+        ASSIMP_LOG_ERROR("Failed to find skeleton file '", filename, "' that is referenced by imported Mesh.");
         return MemoryStreamReaderPtr();
     }
 
@@ -874,7 +874,7 @@ void OgreBinarySerializer::ReadBone(Skeleton *skeleton) {
         throw DeadlyImportError("Ogre Skeleton bone indexes not contiguous. Error at bone index ", bone->id);
     }
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("    ", bone->id, " ", bone->name);
+    ASSIMP_LOG_VERBOSE_DEBUG("    ", bone->id, " ", bone->name);
 
     skeleton->bones.push_back(bone);
 }
@@ -919,7 +919,7 @@ void OgreBinarySerializer::ReadSkeletonAnimation(Skeleton *skeleton) {
 
     skeleton->animations.push_back(anim);
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("    ", anim->name, " (", anim->length, " sec, ", anim->tracks.size(), " tracks)");
+    ASSIMP_LOG_VERBOSE_DEBUG("    ", anim->name, " (", anim->length, " sec, ", anim->tracks.size(), " tracks)");
 }
 
 void OgreBinarySerializer::ReadSkeletonAnimationTrack(Skeleton * /*skeleton*/, Animation *dest) {
diff --git a/code/AssetLib/Ogre/OgreMaterial.cpp b/code/AssetLib/Ogre/OgreMaterial.cpp
index eced651f6..295dedde6 100644
--- a/code/AssetLib/Ogre/OgreMaterial.cpp
+++ b/code/AssetLib/Ogre/OgreMaterial.cpp
@@ -160,16 +160,16 @@ aiMaterial *OgreImporter::ReadMaterial(const std::string &pFile, Assimp::IOSyste
             if (materialFile) {
                 break;
             }
-            ASSIMP_LOG_VERBOSE_DEBUG_F("Source file for material '", materialName, "' ", potentialFiles[i], " does not exist");
+            ASSIMP_LOG_VERBOSE_DEBUG("Source file for material '", materialName, "' ", potentialFiles[i], " does not exist");
         }
         if (!materialFile) {
-            ASSIMP_LOG_ERROR_F("Failed to find source file for material '", materialName, "'");
+            ASSIMP_LOG_ERROR("Failed to find source file for material '", materialName, "'");
             return 0;
         }
 
         std::unique_ptr<IOStream> stream(materialFile);
         if (stream->FileSize() == 0) {
-            ASSIMP_LOG_WARN_F("Source file for material '", materialName, "' is empty (size is 0 bytes)");
+            ASSIMP_LOG_WARN("Source file for material '", materialName, "' is empty (size is 0 bytes)");
             return 0;
         }
 
@@ -184,7 +184,7 @@ aiMaterial *OgreImporter::ReadMaterial(const std::string &pFile, Assimp::IOSyste
         ss << &data[0];
     }
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("Reading material '", materialName, "'");
+    ASSIMP_LOG_VERBOSE_DEBUG("Reading material '", materialName, "'");
 
     aiMaterial *material = new aiMaterial();
     m_textures.clear();
@@ -219,11 +219,11 @@ aiMaterial *OgreImporter::ReadMaterial(const std::string &pFile, Assimp::IOSyste
 
         NextAfterNewLine(ss, linePart);
         if (linePart != partBlockStart) {
-            ASSIMP_LOG_ERROR_F("Invalid material: block start missing near index ", ss.tellg());
+            ASSIMP_LOG_ERROR("Invalid material: block start missing near index ", ss.tellg());
             return material;
         }
 
-        ASSIMP_LOG_VERBOSE_DEBUG_F("material '", materialName, "'");
+        ASSIMP_LOG_VERBOSE_DEBUG("material '", materialName, "'");
 
         while (linePart != partBlockEnd) {
             // Proceed to the first technique
@@ -303,11 +303,11 @@ bool OgreImporter::ReadTechnique(const std::string &techniqueName, stringstream
     ss >> linePart;
 
     if (linePart != partBlockStart) {
-        ASSIMP_LOG_ERROR_F("Invalid material: Technique block start missing near index ", ss.tellg());
+        ASSIMP_LOG_ERROR("Invalid material: Technique block start missing near index ", ss.tellg());
         return false;
     }
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F(" technique '", techniqueName, "'");
+    ASSIMP_LOG_VERBOSE_DEBUG(" technique '", techniqueName, "'");
 
     const string partPass = "pass";
 
@@ -334,11 +334,11 @@ bool OgreImporter::ReadPass(const std::string &passName, stringstream &ss, aiMat
     ss >> linePart;
 
     if (linePart != partBlockStart) {
-        ASSIMP_LOG_ERROR_F("Invalid material: Pass block start missing near index ", ss.tellg());
+        ASSIMP_LOG_ERROR("Invalid material: Pass block start missing near index ", ss.tellg());
         return false;
     }
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("  pass '", passName, "'");
+    ASSIMP_LOG_VERBOSE_DEBUG("  pass '", passName, "'");
 
     const string partAmbient = "ambient";
     const string partDiffuse = "diffuse";
@@ -362,7 +362,7 @@ bool OgreImporter::ReadPass(const std::string &passName, stringstream &ss, aiMat
             ss >> r >> g >> b;
             const aiColor3D color(r, g, b);
 
-            ASSIMP_LOG_VERBOSE_DEBUG_F("   ", linePart, " ", r, " ", g, " ", b);
+            ASSIMP_LOG_VERBOSE_DEBUG("   ", linePart, " ", r, " ", g, " ", b);
 
             if (linePart == partAmbient) {
                 material->AddProperty(&color, 1, AI_MATKEY_COLOR_AMBIENT);
@@ -386,11 +386,11 @@ bool OgreImporter::ReadTextureUnit(const std::string &textureUnitName, stringstr
     ss >> linePart;
 
     if (linePart != partBlockStart) {
-        ASSIMP_LOG_ERROR_F("Invalid material: Texture unit block start missing near index ", ss.tellg());
+        ASSIMP_LOG_ERROR("Invalid material: Texture unit block start missing near index ", ss.tellg());
         return false;
     }
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("   texture_unit '", textureUnitName, "'");
+    ASSIMP_LOG_VERBOSE_DEBUG("   texture_unit '", textureUnitName, "'");
 
     const string partTexture = "texture";
     const string partTextCoordSet = "tex_coord_set";
@@ -420,7 +420,7 @@ bool OgreImporter::ReadTextureUnit(const std::string &textureUnitName, stringstr
 
                 if (posSuffix != string::npos && posUnderscore != string::npos && posSuffix > posUnderscore) {
                     string identifier = ai_tolower(textureRef.substr(posUnderscore, posSuffix - posUnderscore));
-                    ASSIMP_LOG_VERBOSE_DEBUG_F("Detecting texture type from filename postfix '", identifier, "'");
+                    ASSIMP_LOG_VERBOSE_DEBUG("Detecting texture type from filename postfix '", identifier, "'");
 
                     if (identifier == "_n" || identifier == "_nrm" || identifier == "_nrml" || identifier == "_normal" || identifier == "_normals" || identifier == "_normalmap") {
                         textureType = aiTextureType_NORMALS;
@@ -477,14 +477,14 @@ bool OgreImporter::ReadTextureUnit(const std::string &textureUnitName, stringstr
         return false;
     }
     if (textureType == aiTextureType_NONE) {
-        ASSIMP_LOG_WARN("Failed to detect texture type for '" + textureRef + "', ignoring texture_unit.");
+        ASSIMP_LOG_WARN("Failed to detect texture type for '", textureRef, "', ignoring texture_unit.");
         return false;
     }
 
     unsigned int textureTypeIndex = m_textures[textureType];
     m_textures[textureType]++;
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("    texture '", textureRef, "' type ", textureType,
+    ASSIMP_LOG_VERBOSE_DEBUG("    texture '", textureRef, "' type ", textureType,
             " index ", textureTypeIndex, " UV ", uvCoord);
 
     aiString assimpTextureRef(textureRef);
diff --git a/code/AssetLib/Ogre/OgreStructs.cpp b/code/AssetLib/Ogre/OgreStructs.cpp
index 90e2d4465..a2d861172 100644
--- a/code/AssetLib/Ogre/OgreStructs.cpp
+++ b/code/AssetLib/Ogre/OgreStructs.cpp
@@ -545,7 +545,7 @@ aiMesh *SubMesh::ConvertToAssimpMesh(Mesh *parent) {
             dest->mNumUVComponents[0] = static_cast<unsigned int>(uv1Element->ComponentCount());
             dest->mTextureCoords[0] = new aiVector3D[dest->mNumVertices];
         } else {
-            ASSIMP_LOG_WARN(Formatter::format() << "Ogre imported UV0 type " << uv1Element->TypeToString() << " is not compatible with Assimp. Ignoring UV.");
+            ASSIMP_LOG_WARN("Ogre imported UV0 type ", uv1Element->TypeToString(), " is not compatible with Assimp. Ignoring UV.");
             uv1 = 0;
         }
     }
@@ -554,7 +554,7 @@ aiMesh *SubMesh::ConvertToAssimpMesh(Mesh *parent) {
             dest->mNumUVComponents[1] = static_cast<unsigned int>(uv2Element->ComponentCount());
             dest->mTextureCoords[1] = new aiVector3D[dest->mNumVertices];
         } else {
-            ASSIMP_LOG_WARN(Formatter::format() << "Ogre imported UV0 type " << uv2Element->TypeToString() << " is not compatible with Assimp. Ignoring UV.");
+            ASSIMP_LOG_WARN("Ogre imported UV0 type ", uv2Element->TypeToString(), " is not compatible with Assimp. Ignoring UV.");
             uv2 = 0;
         }
     }
diff --git a/code/AssetLib/Ogre/OgreXmlSerializer.cpp b/code/AssetLib/Ogre/OgreXmlSerializer.cpp
index 938ae48f3..70671f251 100644
--- a/code/AssetLib/Ogre/OgreXmlSerializer.cpp
+++ b/code/AssetLib/Ogre/OgreXmlSerializer.cpp
@@ -256,7 +256,7 @@ void OgreXmlSerializer::ReadMesh(MeshXml *mesh) {
 
 void OgreXmlSerializer::ReadGeometry(XmlNode &node, VertexDataXml *dest) {
     dest->count = ReadAttribute<uint32_t>(node, "vertexcount");
-    ASSIMP_LOG_VERBOSE_DEBUG_F("  - Reading geometry of ", dest->count, " vertices");
+    ASSIMP_LOG_VERBOSE_DEBUG("  - Reading geometry of ", dest->count, " vertices");
 
     for (XmlNode currentNode : node.children()) {
         const std::string &currentName = currentNode.name();
@@ -290,7 +290,7 @@ void OgreXmlSerializer::ReadGeometryVertexBuffer(XmlNode &node, VertexDataXml *d
         dest->tangents.reserve(dest->count);
     }
     if (uvs > 0) {
-        ASSIMP_LOG_VERBOSE_DEBUG_F("    - Contains ", uvs, " texture coords");
+        ASSIMP_LOG_VERBOSE_DEBUG("    - Contains ", uvs, " texture coords");
         dest->uvs.resize(uvs);
         for (size_t i = 0, len = dest->uvs.size(); i < len; ++i) {
             dest->uvs[i].reserve(dest->count);
@@ -365,9 +365,9 @@ void OgreXmlSerializer::ReadSubMesh(XmlNode &node, MeshXml *mesh) {
         submesh->usesSharedVertexData = ReadAttribute<bool>(node, anUseSharedVertices);
     }
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("Reading SubMesh ", mesh->subMeshes.size());
-    ASSIMP_LOG_VERBOSE_DEBUG_F("  - Material: '", submesh->materialRef, "'");
-    ASSIMP_LOG_VERBOSE_DEBUG_F("  - Uses shared geometry: ", (submesh->usesSharedVertexData ? "true" : "false"));
+    ASSIMP_LOG_VERBOSE_DEBUG("Reading SubMesh ", mesh->subMeshes.size());
+    ASSIMP_LOG_VERBOSE_DEBUG("  - Material: '", submesh->materialRef, "'");
+    ASSIMP_LOG_VERBOSE_DEBUG("  - Uses shared geometry: ", (submesh->usesSharedVertexData ? "true" : "false"));
 
     // TODO: maybe we have always just 1 faces and 1 geometry and always in this order. this loop will only work correct, when the order
     // of faces and geometry changed, and not if we have more than one of one
@@ -398,7 +398,7 @@ void OgreXmlSerializer::ReadSubMesh(XmlNode &node, MeshXml *mesh) {
                 }
             }
             if (submesh->indexData->faces.size() == submesh->indexData->faceCount) {
-                ASSIMP_LOG_VERBOSE_DEBUG_F("  - Faces ", submesh->indexData->faceCount);
+                ASSIMP_LOG_VERBOSE_DEBUG("  - Faces ", submesh->indexData->faceCount);
             } else {
                 throw DeadlyImportError("Read only ", submesh->indexData->faces.size(), " faces when should have read ", submesh->indexData->faceCount);
             }
@@ -459,7 +459,7 @@ void OgreXmlSerializer::ReadBoneAssignments(XmlNode &node, VertexDataXml *dest)
         }
     }
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("  - ", dest->boneAssignments.size(), " bone assignments");
+    ASSIMP_LOG_VERBOSE_DEBUG("  - ", dest->boneAssignments.size(), " bone assignments");
 }
 
 // Skeleton
@@ -515,12 +515,12 @@ bool OgreXmlSerializer::ImportSkeleton(Assimp::IOSystem *pIOHandler, Mesh *mesh)
 
 XmlParserPtr OgreXmlSerializer::OpenXmlParser(Assimp::IOSystem *pIOHandler, const std::string &filename) {
     if (!EndsWith(filename, ".skeleton.xml", false)) {
-        ASSIMP_LOG_ERROR_F("Imported Mesh is referencing to unsupported '", filename, "' skeleton file.");
+        ASSIMP_LOG_ERROR("Imported Mesh is referencing to unsupported '", filename, "' skeleton file.");
         return XmlParserPtr();
     }
 
     if (!pIOHandler->Exists(filename)) {
-        ASSIMP_LOG_ERROR_F("Failed to find skeleton file '", filename, "' that is referenced by imported Mesh.");
+        ASSIMP_LOG_ERROR("Failed to find skeleton file '", filename, "' that is referenced by imported Mesh.");
         return XmlParserPtr();
     }
 
@@ -631,7 +631,7 @@ void OgreXmlSerializer::ReadAnimationKeyFrames(XmlNode &node, Animation *anim, V
                             if (axis.Equal(zeroVec)) {
                                 axis.x = 1.0f;
                                 if (angle != 0) {
-                                    ASSIMP_LOG_WARN_F("Found invalid a key frame with a zero rotation axis in animation: ", anim->name);
+                                    ASSIMP_LOG_WARN("Found invalid a key frame with a zero rotation axis in animation: ", anim->name);
                                 }
                             }
                             keyframe.rotation = aiQuaternion(axis, angle);
@@ -741,7 +741,7 @@ void OgreXmlSerializer::ReadBones(XmlNode &node, Skeleton *skeleton) {
         as per the Ogre skeleton spec. It might be more that other (later) code in this imported does not break. */
     for (size_t i = 0, len = skeleton->bones.size(); i < len; ++i) {
         Bone *b = skeleton->bones[i];
-        ASSIMP_LOG_VERBOSE_DEBUG_F("    ", b->id, " ", b->name);
+        ASSIMP_LOG_VERBOSE_DEBUG("    ", b->id, " ", b->name);
 
         if (b->id != static_cast<uint16_t>(i)) {
             throw DeadlyImportError("Bone ids are not in sequence starting from 0. Missing index ", i);
diff --git a/code/AssetLib/OpenGEX/OpenGEXImporter.cpp b/code/AssetLib/OpenGEX/OpenGEXImporter.cpp
index 14c9ea37f..9baaa4a12 100644
--- a/code/AssetLib/OpenGEX/OpenGEXImporter.cpp
+++ b/code/AssetLib/OpenGEX/OpenGEXImporter.cpp
@@ -45,6 +45,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <assimp/DefaultIOSystem.h>
 #include <assimp/StringComparison.h>
+#include <assimp/StringUtils.h>
 #include <assimp/DefaultLogger.hpp>
 
 #include <assimp/ai_assert.h>
@@ -206,7 +207,7 @@ USE_ODDLPARSER_NS
 
 //------------------------------------------------------------------------------------------------
 static void propId2StdString(Property *prop, std::string &name, std::string &key) {
-    name = key = "";
+    name = key = std::string();
     if (nullptr == prop) {
         return;
     }
@@ -223,6 +224,18 @@ static void propId2StdString(Property *prop, std::string &name, std::string &key
     }
 }
 
+//------------------------------------------------------------------------------------------------
+static void logDDLParserMessage (LogSeverity severity, const std::string &rawmsg) {
+    std::string msg = ai_str_toprintable(rawmsg);
+    switch (severity) {
+    case ddl_debug_msg: ASSIMP_LOG_DEBUG(msg);         break;
+    case ddl_info_msg:  ASSIMP_LOG_INFO(msg);          break;
+    case ddl_warn_msg:  ASSIMP_LOG_WARN(msg);          break;
+    case ddl_error_msg: ASSIMP_LOG_ERROR(msg);         break;
+    default:            ASSIMP_LOG_VERBOSE_DEBUG(msg); break;
+    }
+}
+
 //------------------------------------------------------------------------------------------------
 OpenGEXImporter::VertexContainer::VertexContainer() :
         m_numColors(0), m_colors(nullptr), m_numUVComps(), m_textureCoords() {
@@ -306,6 +319,7 @@ void OpenGEXImporter::InternReadFile(const std::string &filename, aiScene *pScen
     pIOHandler->Close(file);
 
     OpenDDLParser myParser;
+    myParser.setLogCallback(&logDDLParserMessage);
     myParser.setBuffer(&buffer[0], buffer.size());
     bool success(myParser.parse());
     if (success) {
@@ -712,7 +726,7 @@ void OpenGEXImporter::handleMeshNode(ODDLParser::DDLNode *node, aiScene *pScene)
             } else if ("quads" == propKey) {
                 m_currentMesh->mPrimitiveTypes |= aiPrimitiveType_POLYGON;
             } else {
-                ASSIMP_LOG_WARN_F(propKey, " is not supported primitive type.");
+                ASSIMP_LOG_WARN(propKey, " is not supported primitive type.");
             }
         }
     }
diff --git a/code/AssetLib/OpenGEX/OpenGEXImporter.h b/code/AssetLib/OpenGEX/OpenGEXImporter.h
index 677ef73aa..3c26a4a30 100644
--- a/code/AssetLib/OpenGEX/OpenGEXImporter.h
+++ b/code/AssetLib/OpenGEX/OpenGEXImporter.h
@@ -79,7 +79,7 @@ struct MetricInfo {
     int m_intValue;
 
     MetricInfo()
-    : m_stringValue( "" )
+    : m_stringValue( )
     , m_floatValue( 0.0f )
     , m_intValue( -1 ) {
         // empty
diff --git a/code/AssetLib/Ply/PlyLoader.cpp b/code/AssetLib/Ply/PlyLoader.cpp
index ce52636dd..93d48bcbf 100644
--- a/code/AssetLib/Ply/PlyLoader.cpp
+++ b/code/AssetLib/Ply/PlyLoader.cpp
@@ -172,7 +172,7 @@ void PLYImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
             (headerCheck[1] != 'L' && headerCheck[1] != 'l') ||
             (headerCheck[2] != 'Y' && headerCheck[2] != 'y')) {
         streamedBuffer.close();
-        throw DeadlyImportError("Invalid .ply file: Magic number \'ply\' is no there");
+        throw DeadlyImportError("Invalid .ply file: Incorrect magic number (expected 'ply' or 'PLY').");
     }
 
     std::vector<char> mBuffer2;
diff --git a/code/AssetLib/Q3BSP/Q3BSPFileData.h b/code/AssetLib/Q3BSP/Q3BSPFileData.h
index ba826d541..a121cdbcd 100644
--- a/code/AssetLib/Q3BSP/Q3BSPFileData.h
+++ b/code/AssetLib/Q3BSP/Q3BSPFileData.h
@@ -178,7 +178,7 @@ struct Q3BSPModel {
         m_Textures(),
         m_Lightmaps(),
         m_EntityData(),
-        m_ModelName( "" )
+        m_ModelName()
     {
         // empty
     }
diff --git a/code/AssetLib/Q3BSP/Q3BSPFileImporter.cpp b/code/AssetLib/Q3BSP/Q3BSPFileImporter.cpp
index c66582fea..becfa41fc 100644
--- a/code/AssetLib/Q3BSP/Q3BSPFileImporter.cpp
+++ b/code/AssetLib/Q3BSP/Q3BSPFileImporter.cpp
@@ -75,7 +75,7 @@ static const aiImporterDesc desc = {
     0,
     0,
     0,
-    "pk3"
+    "bsp pk3"
 };
 
 namespace Assimp {
@@ -113,7 +113,7 @@ static void extractIds(const std::string &key, int &id1, int &id2) {
 // ------------------------------------------------------------------------------------------------
 //  Local helper function to normalize filenames.
 static void normalizePathName(const std::string &rPath, std::string &normalizedPath) {
-    normalizedPath = "";
+    normalizedPath = std::string();
     if (rPath.empty()) {
         return;
     }
@@ -183,7 +183,7 @@ void Q3BSPFileImporter::InternReadFile(const std::string &rFile, aiScene *scene,
         throw DeadlyImportError("Failed to open file ", rFile, ".");
     }
 
-    std::string archiveName(""), mapName("");
+    std::string archiveName, mapName;
     separateMapName(rFile, archiveName, mapName);
 
     if (mapName.empty()) {
@@ -202,8 +202,8 @@ void Q3BSPFileImporter::InternReadFile(const std::string &rFile, aiScene *scene,
 // ------------------------------------------------------------------------------------------------
 //  Separates the map name from the import name.
 void Q3BSPFileImporter::separateMapName(const std::string &importName, std::string &archiveName, std::string &mapName) {
-    archiveName = "";
-    mapName = "";
+    archiveName = std::string();
+    mapName = std::string();
     if (importName.empty()) {
         return;
     }
@@ -221,7 +221,7 @@ void Q3BSPFileImporter::separateMapName(const std::string &importName, std::stri
 // ------------------------------------------------------------------------------------------------
 //  Returns the first map in the map archive.
 bool Q3BSPFileImporter::findFirstMapInArchive(ZipArchiveIOSystem &bspArchive, std::string &mapName) {
-    mapName = "";
+    mapName = std::string();
     std::vector<std::string> fileList;
     bspArchive.getFileListExtension(fileList, "bsp");
     if (fileList.empty()) {
@@ -440,13 +440,13 @@ void Q3BSPFileImporter::createMaterials(const Q3BSP::Q3BSPModel *pModel, aiScene
         if (-1 != textureId) {
             sQ3BSPTexture *pTexture = pModel->m_Textures[textureId];
             if (nullptr != pTexture) {
-                std::string tmp("*"), texName("");
+                std::string tmp("*"), texName;
                 tmp += pTexture->strName;
                 tmp += ".jpg";
                 normalizePathName(tmp, texName);
 
                 if (!importTextureFromArchive(pModel, pArchive, pScene, pMatHelper, textureId)) {
-                    ASSIMP_LOG_ERROR("Cannot import texture from archive " + texName);
+                    ASSIMP_LOG_ERROR("Cannot import texture from archive ", texName);
                 }
             }
         }
@@ -512,7 +512,7 @@ size_t Q3BSPFileImporter::countTriangles(const std::vector<Q3BSP::sQ3BSPFace *>
 // ------------------------------------------------------------------------------------------------
 //  Creates the faces-to-material map.
 void Q3BSPFileImporter::createMaterialMap(const Q3BSP::Q3BSPModel *pModel) {
-    std::string key("");
+    std::string key;
     std::vector<sQ3BSPFace *> *pCurFaceArray = nullptr;
     for (size_t idx = 0; idx < pModel->m_Faces.size(); idx++) {
         Q3BSP::sQ3BSPFace *pQ3BSPFace = pModel->m_Faces[idx];
@@ -660,7 +660,7 @@ bool Q3BSPFileImporter::expandFile(ZipArchiveIOSystem *pArchive, const std::stri
 
     if (rExtList.empty()) {
         rFile = rFilename;
-        rExt = "";
+        rExt = std::string();
         return true;
     }
 
diff --git a/code/AssetLib/Q3D/Q3DLoader.cpp b/code/AssetLib/Q3D/Q3DLoader.cpp
index b52f86672..f81026547 100644
--- a/code/AssetLib/Q3D/Q3DLoader.cpp
+++ b/code/AssetLib/Q3D/Q3DLoader.cpp
@@ -47,6 +47,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // internal headers
 #include "Q3DLoader.h"
+#include <assimp/StringUtils.h>
 #include <assimp/StreamReader.h>
 #include <assimp/fast_atof.h>
 #include <assimp/importerdesc.h>
@@ -106,7 +107,12 @@ const aiImporterDesc *Q3DImporter::GetInfo() const {
 // Imports the given file into the given scene structure.
 void Q3DImporter::InternReadFile(const std::string &pFile,
         aiScene *pScene, IOSystem *pIOHandler) {
-    StreamReaderLE stream(pIOHandler->Open(pFile, "rb"));
+
+    auto file = pIOHandler->Open(pFile, "rb");
+    if (!file)
+        throw DeadlyImportError("Quick3D: Could not open ", pFile);
+
+    StreamReaderLE stream(file);
 
     // The header is 22 bytes large
     if (stream.GetRemainingSize() < 22)
@@ -115,11 +121,11 @@ void Q3DImporter::InternReadFile(const std::string &pFile,
     // Check the file's signature
     if (ASSIMP_strincmp((const char *)stream.GetPtr(), "quick3Do", 8) &&
             ASSIMP_strincmp((const char *)stream.GetPtr(), "quick3Ds", 8)) {
-        throw DeadlyImportError("Not a Quick3D file. Signature string is: ", std::string((const char *)stream.GetPtr(), 8));
+        throw DeadlyImportError("Not a Quick3D file. Signature string is: ", ai_str_toprintable((const char *)stream.GetPtr(), 8));
     }
 
     // Print the file format version
-    ASSIMP_LOG_INFO_F("Quick3D File format version: ",
+    ASSIMP_LOG_INFO("Quick3D File format version: ",
             std::string(&((const char *)stream.GetPtr())[8], 2));
 
     // ... an store it
diff --git a/code/AssetLib/SIB/SIBImporter.cpp b/code/AssetLib/SIB/SIBImporter.cpp
index 6898fb65c..0321e7064 100644
--- a/code/AssetLib/SIB/SIBImporter.cpp
+++ b/code/AssetLib/SIB/SIBImporter.cpp
@@ -68,6 +68,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/scene.h>
 #include <assimp/DefaultLogger.hpp>
 #include <assimp/IOSystem.hpp>
+#include <assimp/StringUtils.h>
 
 #include <map>
 
@@ -166,21 +167,20 @@ static aiColor3D ReadColor(StreamReaderLE *stream) {
 }
 
 static void UnknownChunk(StreamReaderLE * /*stream*/, const SIBChunk &chunk) {
-    char temp[5] = {
+    char temp[4] = {
         static_cast<char>((chunk.Tag >> 24) & 0xff),
         static_cast<char>((chunk.Tag >> 16) & 0xff),
         static_cast<char>((chunk.Tag >> 8) & 0xff),
-        static_cast<char>(chunk.Tag & 0xff), '\0'
+        static_cast<char>(chunk.Tag & 0xff)
     };
 
-    ASSIMP_LOG_WARN((Formatter::format(), "SIB: Skipping unknown '", temp, "' chunk."));
+    ASSIMP_LOG_WARN("SIB: Skipping unknown '", ai_str_toprintable(temp, 4), "' chunk.");
 }
 
 // Reads a UTF-16LE string and returns it at UTF-8.
 static aiString ReadString(StreamReaderLE *stream, uint32_t numWChars) {
     if (nullptr == stream || 0 == numWChars) {
-        static const aiString empty;
-        return empty;
+        return aiString();
     }
 
     // Allocate buffers (max expansion is 1 byte -> 4 bytes for UTF-8)
@@ -804,7 +804,12 @@ static void ReadScene(SIB *sib, StreamReaderLE *stream) {
 // Imports the given file into the given scene structure.
 void SIBImporter::InternReadFile(const std::string &pFile,
         aiScene *pScene, IOSystem *pIOHandler) {
-    StreamReaderLE stream(pIOHandler->Open(pFile, "rb"));
+
+    auto file = pIOHandler->Open(pFile, "rb");
+    if (!file)
+        throw DeadlyImportError("SIB: Could not open ", pFile);
+
+    StreamReaderLE stream(file);
 
     // We should have at least one chunk
     if (stream.GetRemainingSize() < 16)
diff --git a/code/AssetLib/STEPParser/STEPFileReader.cpp b/code/AssetLib/STEPParser/STEPFileReader.cpp
index cbf8c07c2..e97ea1e28 100644
--- a/code/AssetLib/STEPParser/STEPFileReader.cpp
+++ b/code/AssetLib/STEPParser/STEPFileReader.cpp
@@ -297,8 +297,8 @@ void STEP::ReadFile(DB& db,const EXPRESS::ConversionSchema& scheme,
     }
 
     if ( !DefaultLogger::isNullLogger()){
-        ASSIMP_LOG_DEBUG((Formatter::format(),"STEP: got ",map.size()," object records with ",
-            db.GetRefs().size()," inverse index entries"));
+        ASSIMP_LOG_DEBUG("STEP: got ",map.size()," object records with ",
+            db.GetRefs().size()," inverse index entries");
     }
 }
 
diff --git a/code/AssetLib/Unreal/UnrealLoader.cpp b/code/AssetLib/Unreal/UnrealLoader.cpp
index 499b49c05..e3ebc05c3 100644
--- a/code/AssetLib/Unreal/UnrealLoader.cpp
+++ b/code/AssetLib/Unreal/UnrealLoader.cpp
@@ -228,9 +228,9 @@ void UnrealImporter::InternReadFile(const std::string &pFile,
     a_path = extension + "_a.3d";
     uc_path = extension + ".uc";
 
-    ASSIMP_LOG_DEBUG_F("UNREAL: data file is ", d_path);
-    ASSIMP_LOG_DEBUG_F("UNREAL: aniv file is ", a_path);
-    ASSIMP_LOG_DEBUG_F("UNREAL: uc file is ", uc_path);
+    ASSIMP_LOG_DEBUG("UNREAL: data file is ", d_path);
+    ASSIMP_LOG_DEBUG("UNREAL: aniv file is ", a_path);
+    ASSIMP_LOG_DEBUG("UNREAL: uc file is ", uc_path);
 
     // and open the files ... we can't live without them
     std::unique_ptr<IOStream> p(pIOHandler->Open(d_path));
diff --git a/code/AssetLib/X/XFileHelper.h b/code/AssetLib/X/XFileHelper.h
index 8ba166350..5bdaf4d35 100644
--- a/code/AssetLib/X/XFileHelper.h
+++ b/code/AssetLib/X/XFileHelper.h
@@ -130,7 +130,7 @@ struct Mesh {
 
     std::vector<Bone> mBones;
 
-    explicit Mesh(const std::string &pName = "") AI_NO_EXCEPT
+    explicit Mesh(const std::string &pName = std::string()) AI_NO_EXCEPT
     : mName( pName )
     , mPositions()
     , mPosFaces()
diff --git a/code/AssetLib/X/XFileImporter.cpp b/code/AssetLib/X/XFileImporter.cpp
index cb245ed74..df1aba331 100644
--- a/code/AssetLib/X/XFileImporter.cpp
+++ b/code/AssetLib/X/XFileImporter.cpp
@@ -602,7 +602,7 @@ void XFileImporter::ConvertMaterials( aiScene* pScene, std::vector<XFile::Materi
             }
 
             if( oldMat.sceneIndex == SIZE_MAX ) {
-                ASSIMP_LOG_WARN_F( "Could not resolve global material reference \"", oldMat.mName, "\"" );
+                ASSIMP_LOG_WARN( "Could not resolve global material reference \"", oldMat.mName, "\"" );
                 oldMat.sceneIndex = 0;
             }
 
@@ -667,8 +667,8 @@ void XFileImporter::ConvertMaterials( aiScene* pScene, std::vector<XFile::Materi
 
                 // convert to lower case for easier comparison
                 for ( unsigned int c = 0; c < sz.length(); ++c ) {
-                    if ( isalpha( sz[ c ] ) ) {
-                        sz[ c ] = (char) tolower( sz[ c ] );
+                    if ( isalpha( (unsigned char) sz[ c ] ) ) {
+                        sz[ c ] = (char) tolower( (unsigned char) sz[ c ] );
                     }
                 }
 
diff --git a/code/AssetLib/X/XFileParser.cpp b/code/AssetLib/X/XFileParser.cpp
index c5ce426ae..494ef5b2b 100644
--- a/code/AssetLib/X/XFileParser.cpp
+++ b/code/AssetLib/X/XFileParser.cpp
@@ -1245,13 +1245,13 @@ unsigned int XFileParser::ReadInt() {
         }
 
         // at least one digit expected
-        if (!isdigit(*mP))
+        if (!isdigit((unsigned char)*mP))
             ThrowException("Number expected.");
 
         // read digits
         unsigned int number = 0;
         while (mP < mEnd) {
-            if (!isdigit(*mP))
+            if (!isdigit((unsigned char)*mP))
                 break;
             number = number * 10 + (*mP - 48);
             mP++;
diff --git a/code/AssetLib/X3D/X3DImporter.cpp b/code/AssetLib/X3D/X3DImporter.cpp
index 287fdeceb..121b7490e 100644
--- a/code/AssetLib/X3D/X3DImporter.cpp
+++ b/code/AssetLib/X3D/X3DImporter.cpp
@@ -167,10 +167,6 @@ bool X3DImporter::CanRead( const std::string &pFile, IOSystem * /*pIOHandler*/,
     return false;
 }
 
-void X3DImporter::GetExtensionList( std::set<std::string> &extensionList ) {
-    extensionList.insert("x3d");
-}
-
 void X3DImporter::InternReadFile( const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler ) {
     std::shared_ptr<IOStream> stream(pIOHandler->Open(pFile, "rb"));
     if (!stream) {
diff --git a/code/AssetLib/X3D/X3DImporter.hpp b/code/AssetLib/X3D/X3DImporter.hpp
index 3d263a2cc..c96bb17d8 100644
--- a/code/AssetLib/X3D/X3DImporter.hpp
+++ b/code/AssetLib/X3D/X3DImporter.hpp
@@ -307,7 +307,6 @@ public:
     /// \param [in] pIOHandler - pointer to IO helper object.
     void ParseFile(const std::string &pFile, IOSystem *pIOHandler);
     bool CanRead(const std::string &pFile, IOSystem *pIOHandler, bool pCheckSig) const;
-    void GetExtensionList(std::set<std::string> &pExtensionList);
     void InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler);
     const aiImporterDesc *GetInfo() const;
     void Clear();
diff --git a/code/AssetLib/XGL/XGLLoader.cpp b/code/AssetLib/XGL/XGLLoader.cpp
index 824f0c2c3..3b84d7ba9 100644
--- a/code/AssetLib/XGL/XGLLoader.cpp
+++ b/code/AssetLib/XGL/XGLLoader.cpp
@@ -142,7 +142,7 @@ void XGLImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 
 	// check whether we can read from the file
 	if (stream.get() == NULL) {
-		throw DeadlyImportError("Failed to open XGL/ZGL file " + pFile + "");
+		throw DeadlyImportError("Failed to open XGL/ZGL file " + pFile);
 	}
 
 	// see if its compressed, if so uncompress it
@@ -200,7 +200,7 @@ void XGLImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 	// parse the XML file
     mXmlParser = new XmlParser;
     if (!mXmlParser->parse(stream.get())) {
-		return;
+        throw DeadlyImportError("XML parse error while loading XGL file ", pFile);
 	}
 
 	TempScope scope;
diff --git a/code/AssetLib/glTF/glTFAsset.h b/code/AssetLib/glTF/glTFAsset.h
index 623f18173..da49a1737 100644
--- a/code/AssetLib/glTF/glTFAsset.h
+++ b/code/AssetLib/glTF/glTFAsset.h
@@ -1033,7 +1033,7 @@ namespace glTF
 
         AssetMetadata()
             : premultipliedAlpha(false)
-            , version("")
+            , version()
         {
         }
     };
diff --git a/code/AssetLib/glTF/glTFExporter.cpp b/code/AssetLib/glTF/glTFExporter.cpp
index 0d644be8b..5e1992319 100644
--- a/code/AssetLib/glTF/glTFExporter.cpp
+++ b/code/AssetLib/glTF/glTFExporter.cpp
@@ -604,7 +604,7 @@ void glTFExporter::ExportMeshes()
 			else
 				msg = "mesh must has vertices and faces.";
 
-            ASSIMP_LOG_WARN_F("GLTF: can not use Open3DGC-compression: ", msg);
+            ASSIMP_LOG_WARN("GLTF: can not use Open3DGC-compression: ", msg);
             comp_allow = false;
 		}
 
diff --git a/code/AssetLib/glTF2/glTF2Asset.h b/code/AssetLib/glTF2/glTF2Asset.h
index fad5cba83..26a2f64c3 100644
--- a/code/AssetLib/glTF2/glTF2Asset.h
+++ b/code/AssetLib/glTF2/glTF2Asset.h
@@ -1071,7 +1071,7 @@ struct AssetMetadata {
     void Read(Document &doc);
 
     AssetMetadata() :
-            version("") {}
+            version() {}
 };
 
 //
diff --git a/code/AssetLib/glTF2/glTF2Importer.cpp b/code/AssetLib/glTF2/glTF2Importer.cpp
index f34b1b451..dbc8267d3 100644
--- a/code/AssetLib/glTF2/glTF2Importer.cpp
+++ b/code/AssetLib/glTF2/glTF2Importer.cpp
@@ -325,7 +325,7 @@ static aiMaterial *ImportMaterial(std::vector<int> &embeddedTexIdxs, Asset &r, M
 
 void glTF2Importer::ImportMaterials(glTF2::Asset &r) {
     const unsigned int numImportedMaterials = unsigned(r.materials.Size());
-    ASSIMP_LOG_DEBUG_F("Importing ", numImportedMaterials, " materials");
+    ASSIMP_LOG_DEBUG("Importing ", numImportedMaterials, " materials");
     Material defaultMaterial;
 
     mScene->mNumMaterials = numImportedMaterials + 1;
@@ -402,7 +402,7 @@ aiColor4D* GetVertexColorsForType(glTF2::Ref<glTF2::Accessor> input) {
 }
 
 void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
-    ASSIMP_LOG_DEBUG_F("Importing ", r.meshes.Size(), " meshes");
+    ASSIMP_LOG_DEBUG("Importing ", r.meshes.Size(), " meshes");
     std::vector<std::unique_ptr<aiMesh>> meshes;
 
     unsigned int k = 0;
@@ -455,14 +455,14 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
 
             if (attr.normal.size() > 0 && attr.normal[0]) {
                 if (attr.normal[0]->count != aim->mNumVertices) {
-                    DefaultLogger::get()->warn("Normal count in mesh \"" + mesh.name + "\" does not match the vertex count, normals ignored.");
+                    DefaultLogger::get()->warn("Normal count in mesh \"", mesh.name, "\" does not match the vertex count, normals ignored.");
                 } else {
                     attr.normal[0]->ExtractData(aim->mNormals);
 
                     // only extract tangents if normals are present
                     if (attr.tangent.size() > 0 && attr.tangent[0]) {
                         if (attr.tangent[0]->count != aim->mNumVertices) {
-                            DefaultLogger::get()->warn("Tangent count in mesh \"" + mesh.name + "\" does not match the vertex count, tangents ignored.");
+                            DefaultLogger::get()->warn("Tangent count in mesh \"", mesh.name, "\" does not match the vertex count, tangents ignored.");
                         } else {
                             // generate bitangents from normals and tangents according to spec
                             Tangent *tangents = nullptr;
@@ -485,7 +485,7 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
 
             for (size_t c = 0; c < attr.color.size() && c < AI_MAX_NUMBER_OF_COLOR_SETS; ++c) {
                 if (attr.color[c]->count != aim->mNumVertices) {
-                    DefaultLogger::get()->warn("Color stream size in mesh \"" + mesh.name +
+                    DefaultLogger::get()->warn("Color stream size in mesh \"", mesh.name,
                                                "\" does not match the vertex count");
                     continue;
                 }
@@ -508,7 +508,7 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                 }
 
                 if (attr.texcoord[tc]->count != aim->mNumVertices) {
-                    DefaultLogger::get()->warn("Texcoord stream size in mesh \"" + mesh.name +
+                    DefaultLogger::get()->warn("Texcoord stream size in mesh \"", mesh.name,
                                                "\" does not match the vertex count");
                     continue;
                 }
@@ -539,7 +539,7 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
 
                     if (needPositions) {
                         if (target.position[0]->count != aim->mNumVertices) {
-                            ASSIMP_LOG_WARN_F("Positions of target ", i, " in mesh \"", mesh.name, "\" does not match the vertex count");
+                            ASSIMP_LOG_WARN("Positions of target ", i, " in mesh \"", mesh.name, "\" does not match the vertex count");
                         } else {
                             aiVector3D *positionDiff = nullptr;
                             target.position[0]->ExtractData(positionDiff);
@@ -551,7 +551,7 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                     }
                     if (needNormals) {
                         if (target.normal[0]->count != aim->mNumVertices) {
-                            ASSIMP_LOG_WARN_F("Normals of target ", i, " in mesh \"", mesh.name, "\" does not match the vertex count");
+                            ASSIMP_LOG_WARN("Normals of target ", i, " in mesh \"", mesh.name, "\" does not match the vertex count");
                         } else {
                             aiVector3D *normalDiff = nullptr;
                             target.normal[0]->ExtractData(normalDiff);
@@ -563,7 +563,7 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                     }
                     if (needTangents) {
                         if (target.tangent[0]->count != aim->mNumVertices) {
-                            ASSIMP_LOG_WARN_F("Tangents of target ", i, " in mesh \"", mesh.name, "\" does not match the vertex count");
+                            ASSIMP_LOG_WARN("Tangents of target ", i, " in mesh \"", mesh.name, "\" does not match the vertex count");
                         } else {
                             Tangent *tangent = nullptr;
                             attr.tangent[0]->ExtractData(tangent);
@@ -785,7 +785,7 @@ void glTF2Importer::ImportCameras(glTF2::Asset &r) {
     if (!r.cameras.Size()) return;
 
     const unsigned int numCameras = r.cameras.Size();
-    ASSIMP_LOG_DEBUG_F("Importing ", numCameras, " cameras");
+    ASSIMP_LOG_DEBUG("Importing ", numCameras, " cameras");
     mScene->mNumCameras = numCameras;
     mScene->mCameras = new aiCamera *[numCameras];
     std::fill(mScene->mCameras, mScene->mCameras + numCameras, nullptr);
@@ -822,7 +822,7 @@ void glTF2Importer::ImportLights(glTF2::Asset &r) {
         return;
 
     const unsigned int numLights = r.lights.Size();
-    ASSIMP_LOG_DEBUG_F("Importing ", numLights, " lights");
+    ASSIMP_LOG_DEBUG("Importing ", numLights, " lights");
     mScene->mNumLights = numLights;
     mScene->mLights = new aiLight *[numLights];
     std::fill(mScene->mLights, mScene->mLights + numLights, nullptr);
@@ -1329,7 +1329,7 @@ void glTF2Importer::ImportAnimations(glTF2::Asset &r) {
     if (!r.scene) return;
 
     const unsigned numAnimations = r.animations.Size();
-    ASSIMP_LOG_DEBUG_F("Importing ", numAnimations, " animations");
+    ASSIMP_LOG_DEBUG("Importing ", numAnimations, " animations");
     mScene->mNumAnimations = numAnimations;
     if (mScene->mNumAnimations == 0) {
         return;
@@ -1445,7 +1445,7 @@ void glTF2Importer::ImportEmbeddedTextures(glTF2::Asset &r) {
     if (numEmbeddedTexs == 0)
         return;
 
-      ASSIMP_LOG_DEBUG_F("Importing ", numEmbeddedTexs, " embedded textures");
+      ASSIMP_LOG_DEBUG("Importing ", numEmbeddedTexs, " embedded textures");
 
     mScene->mTextures = new aiTexture *[numEmbeddedTexs];
     std::fill(mScene->mTextures, mScene->mTextures + numEmbeddedTexs, nullptr);
diff --git a/code/CApi/CInterfaceIOWrapper.cpp b/code/CApi/CInterfaceIOWrapper.cpp
index ac358a4a8..8e2ac95c0 100644
--- a/code/CApi/CInterfaceIOWrapper.cpp
+++ b/code/CApi/CInterfaceIOWrapper.cpp
@@ -47,7 +47,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 namespace Assimp {
 
-CIOStreamWrapper::~CIOStreamWrapper(void) {
+CIOStreamWrapper::~CIOStreamWrapper() {
     /* Various places depend on this destructor to close the file */
     if (mFile) {
         mIO->mFileSystem->CloseProc(mIO->mFileSystem, mFile);
@@ -78,7 +78,7 @@ aiReturn CIOStreamWrapper::Seek(size_t pOffset,
 }
 
 // ...................................................................
-size_t CIOStreamWrapper::Tell(void) const {
+size_t CIOStreamWrapper::Tell() const {
     return mFile->TellProc(mFile);
 }
 
diff --git a/code/Common/BaseImporter.cpp b/code/Common/BaseImporter.cpp
index 0657216cf..0f41e9e65 100644
--- a/code/Common/BaseImporter.cpp
+++ b/code/Common/BaseImporter.cpp
@@ -65,20 +65,6 @@ using namespace Assimp;
 // Constructor to be privately used by Importer
 BaseImporter::BaseImporter() AI_NO_EXCEPT
         : m_progress() {
-    /**
-    * Assimp Importer
-    * unit conversions available
-    * if you need another measurment unit add it below.
-    * it's currently defined in assimp that we prefer meters.
-    *
-    * NOTE: Initialised here rather than in the header file
-    * to workaround a VS2013 bug with brace initialisers
-    * */
-    importerUnits[ImporterUnits::M] = 1.0;
-    importerUnits[ImporterUnits::CM] = 0.01;
-    importerUnits[ImporterUnits::MM] = 0.001;
-    importerUnits[ImporterUnits::INCHES] = 0.0254;
-    importerUnits[ImporterUnits::FEET] = 0.3048;
 }
 
 // ------------------------------------------------------------------------------------------------
@@ -97,7 +83,7 @@ void BaseImporter::UpdateImporterScale(Importer *pImp) {
     // Set active scaling
     pImp->SetPropertyFloat(AI_CONFIG_APP_SCALE_KEY, static_cast<float>(activeScale));
 
-    ASSIMP_LOG_DEBUG_F("UpdateImporterScale scale set: %f", activeScale);
+    ASSIMP_LOG_DEBUG("UpdateImporterScale scale set: ", activeScale);
 }
 
 // ------------------------------------------------------------------------------------------------
@@ -193,7 +179,7 @@ void BaseImporter::GetExtensionList(std::set<std::string> &extensions) {
         }
 
         for (size_t i = 0; i < read; ++i) {
-            buffer[i] = static_cast<char>(::tolower(buffer[i]));
+            buffer[i] = static_cast<char>(::tolower((unsigned char)buffer[i]));
         }
 
         // It is not a proper handling of unicode files here ...
@@ -214,7 +200,7 @@ void BaseImporter::GetExtensionList(std::set<std::string> &extensions) {
             token.clear();
             const char *ptr(tokens[i]);
             for (size_t tokIdx = 0; tokIdx < len; ++tokIdx) {
-                token.push_back(static_cast<char>(tolower(*ptr)));
+                token.push_back(static_cast<char>(tolower(static_cast<unsigned char>(*ptr))));
                 ++ptr;
             }
             const char *r = strstr(buffer, token.c_str());
@@ -223,13 +209,13 @@ void BaseImporter::GetExtensionList(std::set<std::string> &extensions) {
             }
             // We need to make sure that we didn't accidentially identify the end of another token as our token,
             // e.g. in a previous version the "gltf " present in some gltf files was detected as "f "
-            if (noAlphaBeforeTokens && (r != buffer && isalpha(r[-1]))) {
+            if (noAlphaBeforeTokens && (r != buffer && isalpha(static_cast<unsigned char>(r[-1])))) {
                 continue;
             }
             // We got a match, either we don't care where it is, or it happens to
             // be in the beginning of the file / line
             if (!tokensSol || r == buffer || r[-1] == '\r' || r[-1] == '\n') {
-                ASSIMP_LOG_DEBUG_F("Found positive match for header keyword: ", tokens[i]);
+                ASSIMP_LOG_DEBUG("Found positive match for header keyword: ", tokens[i]);
                 return true;
             }
         }
@@ -271,7 +257,7 @@ std::string BaseImporter::GetExtension(const std::string &file) {
 
     // no file extension at all
     if (pos == std::string::npos) {
-        return "";
+        return std::string();
     }
 
     // thanks to Andy Maloney for the hint
@@ -618,7 +604,7 @@ void BatchLoader::LoadAll() {
 
         if (!DefaultLogger::isNullLogger()) {
             ASSIMP_LOG_INFO("%%% BEGIN EXTERNAL FILE %%%");
-            ASSIMP_LOG_INFO_F("File: ", (*it).file);
+            ASSIMP_LOG_INFO("File: ", (*it).file);
         }
         m_data->pImporter->ReadFile((*it).file, pp);
         (*it).scene = m_data->pImporter->GetOrphanedScene();
diff --git a/code/Common/DefaultIOSystem.cpp b/code/Common/DefaultIOSystem.cpp
index ec7a311cf..98d51a17d 100644
--- a/code/Common/DefaultIOSystem.cpp
+++ b/code/Common/DefaultIOSystem.cpp
@@ -176,7 +176,7 @@ inline static std::string MakeAbsolutePath(const char *in) {
     if (!ret) {
         // preserve the input path, maybe someone else is able to fix
         // the path before it is accessed (e.g. our file system filter)
-        ASSIMP_LOG_WARN_F("Invalid path: ", std::string(in));
+        ASSIMP_LOG_WARN("Invalid path: ", std::string(in));
         out = in;
     }
     return out;
diff --git a/code/Common/DefaultLogger.cpp b/code/Common/DefaultLogger.cpp
index aa13ca5ce..4fa9c865b 100644
--- a/code/Common/DefaultLogger.cpp
+++ b/code/Common/DefaultLogger.cpp
@@ -177,9 +177,7 @@ void Logger::debug(const char *message) {
 // ----------------------------------------------------------------------------------
 void Logger::verboseDebug(const char *message) {
 
-    // SECURITY FIX: otherwise it's easy to produce overruns since
-    // sometimes importers will include data from the input file
-    // (i.e. node names) in their messages.
+    // SECURITY FIX: see above
     if (strlen(message) > MAX_LOG_MESSAGE_LENGTH) {
         return;
     }
diff --git a/code/Common/FileSystemFilter.h b/code/Common/FileSystemFilter.h
index 1440cf97d..6585f9df6 100644
--- a/code/Common/FileSystemFilter.h
+++ b/code/Common/FileSystemFilter.h
@@ -76,7 +76,7 @@ public:
         if (std::string::npos != (ss2 = mBase.find_last_of("\\/")))  {
             mBase.erase(ss2,mBase.length()-ss2);
         } else {
-            mBase = "";
+            mBase = std::string();
         }
 
         // make sure the directory is terminated properly
@@ -89,7 +89,7 @@ public:
             mBase += getOsSeparator();
         }
 
-        DefaultLogger::get()->info("Import root directory is \'" + mBase + "\'");
+        DefaultLogger::get()->info("Import root directory is \'", mBase, "\'");
     }
 
     /** Destructor. */
diff --git a/code/Common/Importer.cpp b/code/Common/Importer.cpp
index db7fc9e1c..a2ad041fb 100644
--- a/code/Common/Importer.cpp
+++ b/code/Common/Importer.cpp
@@ -149,7 +149,7 @@ void AllocateFromAssimpHeap::operator delete[] ( void* data)    {
 Importer::Importer()
  : pimpl( new ImporterPimpl ) {
     pimpl->mScene = nullptr;
-    pimpl->mErrorString = "";
+    pimpl->mErrorString = std::string();
 
     // Allocate a default IO handler
     pimpl->mIOHandler = new DefaultIOSystem;
@@ -232,7 +232,7 @@ aiReturn Importer::RegisterLoader(BaseImporter* pImp) {
 
 #ifdef ASSIMP_BUILD_DEBUG
         if (IsExtensionSupported(*it)) {
-            ASSIMP_LOG_WARN_F("The file extension ", *it, " is already in use");
+            ASSIMP_LOG_WARN("The file extension ", *it, " is already in use");
         }
 #endif
         baked += *it;
@@ -240,7 +240,7 @@ aiReturn Importer::RegisterLoader(BaseImporter* pImp) {
 
     // add the loader
     pimpl->mImporter.push_back(pImp);
-    ASSIMP_LOG_INFO_F("Registering custom importer for these file extensions: ", baked);
+    ASSIMP_LOG_INFO("Registering custom importer for these file extensions: ", baked);
     ASSIMP_END_EXCEPTION_REGION(aiReturn);
     
     return AI_SUCCESS;
@@ -387,7 +387,7 @@ void Importer::FreeScene( ) {
     delete pimpl->mScene;
     pimpl->mScene = nullptr;
 
-    pimpl->mErrorString = "";
+    pimpl->mErrorString = std::string();
     pimpl->mException = std::exception_ptr();
     ASSIMP_END_EXCEPTION_REGION(void);
 }
@@ -434,7 +434,7 @@ aiScene* Importer::GetOrphanedScene() {
     ASSIMP_BEGIN_EXCEPTION_REGION();
     pimpl->mScene = nullptr;
 
-    pimpl->mErrorString = ""; // reset error string
+    pimpl->mErrorString = std::string();
     pimpl->mException = std::exception_ptr();
     ASSIMP_END_EXCEPTION_REGION(aiScene*);
     
@@ -519,7 +519,7 @@ const aiScene* Importer::ReadFileFromMemory( const void* pBuffer,
 // ------------------------------------------------------------------------------------------------
 void WriteLogOpening(const std::string& file) {
     
-    ASSIMP_LOG_INFO_F("Load ", file);
+    ASSIMP_LOG_INFO("Load ", file);
 
     // print a full version dump. This is nice because we don't
     // need to ask the authors of incoming bug reports for
@@ -665,7 +665,7 @@ const aiScene* Importer::ReadFile( const char* _pFile, unsigned int pFlags) {
         if ( nullptr != desc ) {
             ext = desc->mName;
         }
-        ASSIMP_LOG_INFO("Found a matching importer for this file format: " + ext + "." );
+        ASSIMP_LOG_INFO("Found a matching importer for this file format: ", ext, "." );
         pimpl->mProgressHandler->UpdateFileRead( 0, fileSize );
 
         if (profiler) {
diff --git a/code/Common/ImporterRegistry.cpp b/code/Common/ImporterRegistry.cpp
index a902fc89d..ddfcf6798 100644
--- a/code/Common/ImporterRegistry.cpp
+++ b/code/Common/ImporterRegistry.cpp
@@ -48,6 +48,7 @@ corresponding preprocessor flag to selectively disable formats.
 
 #include <assimp/BaseImporter.h>
 #include <vector>
+#include <cstdlib>
 
 // ------------------------------------------------------------------------------------------------
 // Importers
@@ -204,7 +205,17 @@ corresponding preprocessor flag to selectively disable formats.
 namespace Assimp {
 
 // ------------------------------------------------------------------------------------------------
-void GetImporterInstanceList(std::vector<BaseImporter *> &out) {
+void GetImporterInstanceList(std::vector<BaseImporter *> &out) {    
+    
+    // Some importers may be unimplemented or otherwise unsuitable for general use
+    // in their current state. Devs can set ASSIMP_ENABLE_DEV_IMPORTERS in their
+    // local environment to enable them, otherwise they're left out of the registry.
+    const char *envStr = std::getenv("ASSIMP_ENABLE_DEV_IMPORTERS");
+    bool devImportersEnabled = envStr && strcmp(envStr, "0");
+
+    // Ensure no unused var warnings if all uses are #ifndef'd away below:
+    (void)devImportersEnabled;
+
     // ----------------------------------------------------------------------------
     // Add an instance of each worker class here
     // (register_new_importers_here)
@@ -354,7 +365,9 @@ void GetImporterInstanceList(std::vector<BaseImporter *> &out) {
     out.push_back(new D3MFImporter());
 #endif
 #ifndef ASSIMP_BUILD_NO_X3D_IMPORTER
-    out.push_back(new X3DImporter());
+    if (devImportersEnabled) { // https://github.com/assimp/assimp/issues/3647
+        out.push_back(new X3DImporter());
+    }
 #endif
 #ifndef ASSIMP_BUILD_NO_MMD_IMPORTER
     out.push_back(new MMDImporter());
diff --git a/code/Common/SceneCombiner.cpp b/code/Common/SceneCombiner.cpp
index e39660cd6..555d46b6a 100644
--- a/code/Common/SceneCombiner.cpp
+++ b/code/Common/SceneCombiner.cpp
@@ -45,7 +45,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 // possible as new fields are added to assimp structures.
 
 // ----------------------------------------------------------------------------
-/** 
+/**
   * @file Implements Assimp::SceneCombiner. This is a smart utility
   *       class that combines multiple scenes, meshes, ... into one. Currently
   *       these utilities are used by the IRR and LWS loaders and the
@@ -359,7 +359,7 @@ void SceneCombiner::MergeScenes(aiScene **_dest, aiScene *master, std::vector<At
 
     // generate the output texture list + an offset table for all texture indices
     if (dest->mNumTextures) {
-        aiTexture **pip = dest->mTextures = new aiTexture *[dest->mNumMaterials];
+        aiTexture **pip = dest->mTextures = new aiTexture *[dest->mNumTextures];
         cnt = 0;
         for (unsigned int n = 0; n < src.size(); ++n) {
             SceneHelper *cur = &src[n];
@@ -612,7 +612,7 @@ void SceneCombiner::MergeScenes(aiScene **_dest, aiScene *master, std::vector<At
                 }
             }
             if (!(*it).resolved) {
-                ASSIMP_LOG_ERROR_F("SceneCombiner: Failed to resolve attachment ", (*it).node->mName.data,
+                ASSIMP_LOG_ERROR("SceneCombiner: Failed to resolve attachment ", (*it).node->mName.data,
                         " ", (*it).attachToNode->mName.data);
             }
         }
@@ -638,6 +638,8 @@ void SceneCombiner::MergeScenes(aiScene **_dest, aiScene *master, std::vector<At
         deleteMe->mMaterials = nullptr;
         delete[] deleteMe->mAnimations;
         deleteMe->mAnimations = nullptr;
+        delete[] deleteMe->mTextures;
+        deleteMe->mTextures = nullptr;
 
         deleteMe->mRootNode = nullptr;
 
diff --git a/code/Common/Subdivision.cpp b/code/Common/Subdivision.cpp
index 76fc83404..9e7577a04 100644
--- a/code/Common/Subdivision.cpp
+++ b/code/Common/Subdivision.cpp
@@ -336,7 +336,7 @@ void CatmullClarkSubdivider::InternSubdivide(
                 // Report the number of bad edges. bad edges are referenced by less than two
                 // faces in the mesh. They occur at outer model boundaries in non-closed
                 // shapes.
-                ASSIMP_LOG_VERBOSE_DEBUG_F("Catmull-Clark Subdivider: got ", bad_cnt, " bad edges touching only one face (totally ",
+                ASSIMP_LOG_VERBOSE_DEBUG("Catmull-Clark Subdivider: got ", bad_cnt, " bad edges touching only one face (totally ",
                         static_cast<unsigned int>(edges.size()), " edges). ");
             }
         }
diff --git a/code/Common/scene.cpp b/code/Common/scene.cpp
index 82430f5fc..67feb7afb 100644
--- a/code/Common/scene.cpp
+++ b/code/Common/scene.cpp
@@ -43,7 +43,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/scene.h>
 
 aiNode::aiNode()
-: mName("")
+: mName()
 , mParent(nullptr)
 , mNumChildren(0)
 , mChildren(nullptr)
diff --git a/code/Material/MaterialSystem.cpp b/code/Material/MaterialSystem.cpp
index 310dea29d..c35a1aa93 100644
--- a/code/Material/MaterialSystem.cpp
+++ b/code/Material/MaterialSystem.cpp
@@ -160,7 +160,7 @@ aiReturn aiGetMaterialFloatArray(const aiMaterial *pMat,
                 break;
             }
             if (!IsSpace(*cur)) {
-                ASSIMP_LOG_ERROR("Material property" + std::string(pKey) +
+                ASSIMP_LOG_ERROR("Material property", pKey,
                                  " is a string; failed to parse a float array out of it.");
                 return AI_FAILURE;
             }
@@ -238,7 +238,7 @@ aiReturn aiGetMaterialIntegerArray(const aiMaterial *pMat,
                 break;
             }
             if (!IsSpace(*cur)) {
-                ASSIMP_LOG_ERROR("Material property" + std::string(pKey) +
+                ASSIMP_LOG_ERROR("Material property", pKey,
                                  " is a string; failed to parse an integer array out of it.");
                 return AI_FAILURE;
             }
@@ -306,8 +306,7 @@ aiReturn aiGetMaterialString(const aiMaterial *pMat,
         memcpy(pOut->data, prop->mData + 4, pOut->length + 1);
     } else {
         // TODO - implement lexical cast as well
-        ASSIMP_LOG_ERROR("Material property" + std::string(pKey) +
-                         " was found, but is no string");
+        ASSIMP_LOG_ERROR("Material property", pKey, " was found, but is no string");
         return AI_FAILURE;
     }
     return AI_SUCCESS;
diff --git a/code/PostProcessing/ArmaturePopulate.cpp b/code/PostProcessing/ArmaturePopulate.cpp
index 88b0b2d7c..fdf7508d0 100644
--- a/code/PostProcessing/ArmaturePopulate.cpp
+++ b/code/PostProcessing/ArmaturePopulate.cpp
@@ -77,12 +77,12 @@ void ArmaturePopulate::Execute(aiScene *out) {
 
     BuildBoneStack(out->mRootNode, out->mRootNode, out, bones, bone_stack, nodes);
 
-    ASSIMP_LOG_DEBUG_F("Bone stack size: ", bone_stack.size());
+    ASSIMP_LOG_DEBUG("Bone stack size: ", bone_stack.size());
 
     for (std::pair<aiBone *, aiNode *> kvp : bone_stack) {
         aiBone *bone = kvp.first;
         aiNode *bone_node = kvp.second;
-        ASSIMP_LOG_VERBOSE_DEBUG_F("active node lookup: ", bone->mName.C_Str());
+        ASSIMP_LOG_VERBOSE_DEBUG("active node lookup: ", bone->mName.C_Str());
         // lcl transform grab - done in generate_nodes :)
 
         // bone->mOffsetMatrix = bone_node->mTransformation;
@@ -179,7 +179,7 @@ void ArmaturePopulate::BuildBoneStack(aiNode *,
         if (node == nullptr) {
             node_stack.clear();
             BuildNodeList(root_node, node_stack);
-            ASSIMP_LOG_VERBOSE_DEBUG_F("Resetting bone stack: nullptr element ", bone->mName.C_Str());
+            ASSIMP_LOG_VERBOSE_DEBUG("Resetting bone stack: nullptr element ", bone->mName.C_Str());
 
             node = GetNodeFromStack(bone->mName, node_stack);
 
@@ -189,7 +189,7 @@ void ArmaturePopulate::BuildBoneStack(aiNode *,
             }
         }
 
-        ASSIMP_LOG_VERBOSE_DEBUG_F("Successfully added bone[", bone->mName.C_Str(), "] to stack and bone node is: ", node->mName.C_Str());
+        ASSIMP_LOG_VERBOSE_DEBUG("Successfully added bone[", bone->mName.C_Str(), "] to stack and bone node is: ", node->mName.C_Str());
 
         bone_stack.insert(std::pair<aiBone *, aiNode *>(bone, node));
     }
@@ -203,7 +203,7 @@ aiNode *ArmaturePopulate::GetArmatureRoot(aiNode *bone_node,
                                           std::vector<aiBone *> &bone_list) {
     while (nullptr != bone_node) {
         if (!IsBoneNode(bone_node->mName, bone_list)) {
-            ASSIMP_LOG_VERBOSE_DEBUG_F("GetArmatureRoot() Found valid armature: ", bone_node->mName.C_Str());
+            ASSIMP_LOG_VERBOSE_DEBUG("GetArmatureRoot() Found valid armature: ", bone_node->mName.C_Str());
             return bone_node;
         }
 
@@ -247,7 +247,7 @@ aiNode *ArmaturePopulate::GetNodeFromStack(const aiString &node_name,
     }
 
     if (found != nullptr) {
-        ASSIMP_LOG_INFO_F("Removed node from stack: ", found->mName.C_Str());
+        ASSIMP_LOG_INFO("Removed node from stack: ", found->mName.C_Str());
         // now pop the element from the node list
         nodes.erase(iter);
 
diff --git a/code/PostProcessing/CalcTangentsProcess.cpp b/code/PostProcessing/CalcTangentsProcess.cpp
index cdafda3b6..46feff4a1 100644
--- a/code/PostProcessing/CalcTangentsProcess.cpp
+++ b/code/PostProcessing/CalcTangentsProcess.cpp
@@ -129,7 +129,7 @@ bool CalcTangentsProcess::ProcessMesh(aiMesh *pMesh, unsigned int meshIndex) {
         return false;
     }
     if (configSourceUV >= AI_MAX_NUMBER_OF_TEXTURECOORDS || !pMesh->mTextureCoords[configSourceUV]) {
-        ASSIMP_LOG_ERROR((Formatter::format("Failed to compute tangents; need UV data in channel"), configSourceUV));
+        ASSIMP_LOG_ERROR("Failed to compute tangents; need UV data in channel", configSourceUV);
         return false;
     }
 
diff --git a/code/PostProcessing/DeboneProcess.cpp b/code/PostProcessing/DeboneProcess.cpp
index b5ed66268..3783bb65c 100644
--- a/code/PostProcessing/DeboneProcess.cpp
+++ b/code/PostProcessing/DeboneProcess.cpp
@@ -148,7 +148,7 @@ void DeboneProcess::Execute( aiScene* pScene)
                 }
 
                 if(!DefaultLogger::isNullLogger()) {
-                    ASSIMP_LOG_INFO_F("Removed %u bones. Input bones:", in - out, ". Output bones: ", out);
+                    ASSIMP_LOG_INFO("Removed %u bones. Input bones:", in - out, ". Output bones: ", out);
                 }
 
                 // and destroy the source mesh. It should be completely contained inside the new submeshes
diff --git a/code/PostProcessing/EmbedTexturesProcess.cpp b/code/PostProcessing/EmbedTexturesProcess.cpp
index dc304ff9c..7e435e556 100644
--- a/code/PostProcessing/EmbedTexturesProcess.cpp
+++ b/code/PostProcessing/EmbedTexturesProcess.cpp
@@ -93,7 +93,7 @@ void EmbedTexturesProcess::Execute(aiScene* pScene) {
         }
     }
 
-    ASSIMP_LOG_INFO_F("EmbedTexturesProcess finished. Embedded ", embeddedTexturesCount, " textures." );
+    ASSIMP_LOG_INFO("EmbedTexturesProcess finished. Embedded ", embeddedTexturesCount, " textures." );
 }
 
 bool EmbedTexturesProcess::addTexture(aiScene* pScene, std::string path) const {
@@ -103,7 +103,7 @@ bool EmbedTexturesProcess::addTexture(aiScene* pScene, std::string path) const {
     // Test path directly
     std::ifstream file(imagePath, std::ios::binary | std::ios::ate);
     if ((imageSize = file.tellg()) == std::streampos(-1)) {
-        ASSIMP_LOG_WARN_F("EmbedTexturesProcess: Cannot find image: ", imagePath, ". Will try to find it in root folder.");
+        ASSIMP_LOG_WARN("EmbedTexturesProcess: Cannot find image: ", imagePath, ". Will try to find it in root folder.");
 
         // Test path in root path
         imagePath = mRootPath + path;
@@ -113,7 +113,7 @@ bool EmbedTexturesProcess::addTexture(aiScene* pScene, std::string path) const {
             imagePath = mRootPath + path.substr(path.find_last_of("\\/") + 1u);
             file.open(imagePath, std::ios::binary | std::ios::ate);
             if ((imageSize = file.tellg()) == std::streampos(-1)) {
-                ASSIMP_LOG_ERROR_F("EmbedTexturesProcess: Unable to embed texture: ", path, ".");
+                ASSIMP_LOG_ERROR("EmbedTexturesProcess: Unable to embed texture: ", path, ".");
                 return false;
             }
         }
diff --git a/code/PostProcessing/FindDegenerates.cpp b/code/PostProcessing/FindDegenerates.cpp
index 1fc58cf59..eae91ff02 100644
--- a/code/PostProcessing/FindDegenerates.cpp
+++ b/code/PostProcessing/FindDegenerates.cpp
@@ -291,7 +291,7 @@ evil_jump_outside:
     }
 
     if (deg && !DefaultLogger::isNullLogger()) {
-        ASSIMP_LOG_WARN_F( "Found ", deg, " degenerated primitives");
+        ASSIMP_LOG_WARN( "Found ", deg, " degenerated primitives");
     }
     return false;
 }
diff --git a/code/PostProcessing/FindInstancesProcess.cpp b/code/PostProcessing/FindInstancesProcess.cpp
index 98527e531..ab5f52b78 100644
--- a/code/PostProcessing/FindInstancesProcess.cpp
+++ b/code/PostProcessing/FindInstancesProcess.cpp
@@ -267,7 +267,7 @@ void FindInstancesProcess::Execute( aiScene* pScene)
 
             // write to log
             if (!DefaultLogger::isNullLogger()) {
-                ASSIMP_LOG_INFO_F( "FindInstancesProcess finished. Found ", (pScene->mNumMeshes - numMeshesOut), " instances" );
+                ASSIMP_LOG_INFO( "FindInstancesProcess finished. Found ", (pScene->mNumMeshes - numMeshesOut), " instances" );
             }
             pScene->mNumMeshes = numMeshesOut;
         } else {
diff --git a/code/PostProcessing/FindInvalidDataProcess.cpp b/code/PostProcessing/FindInvalidDataProcess.cpp
index 9c19c606a..ea7d99094 100644
--- a/code/PostProcessing/FindInvalidDataProcess.cpp
+++ b/code/PostProcessing/FindInvalidDataProcess.cpp
@@ -200,7 +200,7 @@ inline bool ProcessArray(T *&in, unsigned int num, const char *name,
         const std::vector<bool> &dirtyMask, bool mayBeIdentical = false, bool mayBeZero = true) {
     const char *err = ValidateArrayContents(in, num, dirtyMask, mayBeIdentical, mayBeZero);
     if (err) {
-        ASSIMP_LOG_ERROR_F("FindInvalidDataProcess fails on mesh ", name, ": ", err);
+        ASSIMP_LOG_ERROR("FindInvalidDataProcess fails on mesh ", name, ": ", err);
         delete[] in;
         in = nullptr;
         return true;
diff --git a/code/PostProcessing/FixNormalsStep.cpp b/code/PostProcessing/FixNormalsStep.cpp
index 850da5e25..09b1f1908 100644
--- a/code/PostProcessing/FixNormalsStep.cpp
+++ b/code/PostProcessing/FixNormalsStep.cpp
@@ -164,7 +164,7 @@ bool FixInfacingNormalsProcess::ProcessMesh( aiMesh* pcMesh, unsigned int index)
     // now compare the volumes of the bounding boxes
     if (std::fabs(fDelta0_x * fDelta0_y * fDelta0_z) < std::fabs(fDelta1_x * fDelta1_yz)) {
         if (!DefaultLogger::isNullLogger()) {
-            ASSIMP_LOG_INFO_F("Mesh ", index, ": Normals are facing inwards (or the mesh is planar)", index);
+            ASSIMP_LOG_INFO("Mesh ", index, ": Normals are facing inwards (or the mesh is planar)", index);
         }
 
         // Invert normals
diff --git a/code/PostProcessing/GenFaceNormalsProcess.cpp b/code/PostProcessing/GenFaceNormalsProcess.cpp
index a73df2b5d..3e8612d29 100644
--- a/code/PostProcessing/GenFaceNormalsProcess.cpp
+++ b/code/PostProcessing/GenFaceNormalsProcess.cpp
@@ -70,6 +70,7 @@ GenFaceNormalsProcess::~GenFaceNormalsProcess() {
 // Returns whether the processing step is present in the given flag field.
 bool GenFaceNormalsProcess::IsActive(unsigned int pFlags) const {
     force_ = (pFlags & aiProcess_ForceGenNormals) != 0;
+    flippedWindingOrder_ = (pFlags & aiProcess_FlipWindingOrder) != 0;
     return (pFlags & aiProcess_GenNormals) != 0;
 }
 
@@ -134,6 +135,8 @@ bool GenFaceNormalsProcess::GenMeshFaceNormals(aiMesh *pMesh) {
         const aiVector3D *pV1 = &pMesh->mVertices[face.mIndices[0]];
         const aiVector3D *pV2 = &pMesh->mVertices[face.mIndices[1]];
         const aiVector3D *pV3 = &pMesh->mVertices[face.mIndices[face.mNumIndices - 1]];
+        if (flippedWindingOrder_)
+            std::swap( pV2, pV3 );
         const aiVector3D vNor = ((*pV2 - *pV1) ^ (*pV3 - *pV1)).NormalizeSafe();
 
         for (unsigned int i = 0; i < face.mNumIndices; ++i) {
diff --git a/code/PostProcessing/GenFaceNormalsProcess.h b/code/PostProcessing/GenFaceNormalsProcess.h
index 4b9222af3..eefff6c73 100644
--- a/code/PostProcessing/GenFaceNormalsProcess.h
+++ b/code/PostProcessing/GenFaceNormalsProcess.h
@@ -80,6 +80,7 @@ public:
 private:
     bool GenMeshFaceNormals(aiMesh* pcMesh);
     mutable bool force_ = false;
+    mutable bool flippedWindingOrder_ = false;
 };
 
 } // end of namespace Assimp
diff --git a/code/PostProcessing/GenVertexNormalsProcess.cpp b/code/PostProcessing/GenVertexNormalsProcess.cpp
index 5c9a6b754..e82bc3e6f 100644
--- a/code/PostProcessing/GenVertexNormalsProcess.cpp
+++ b/code/PostProcessing/GenVertexNormalsProcess.cpp
@@ -70,6 +70,7 @@ GenVertexNormalsProcess::~GenVertexNormalsProcess() {
 // Returns whether the processing step is present in the given flag field.
 bool GenVertexNormalsProcess::IsActive(unsigned int pFlags) const {
     force_ = (pFlags & aiProcess_ForceGenNormals) != 0;
+    flippedWindingOrder_ = (pFlags & aiProcess_FlipWindingOrder) != 0;
     return (pFlags & aiProcess_GenSmoothNormals) != 0;
 }
 
@@ -142,6 +143,8 @@ bool GenVertexNormalsProcess::GenMeshVertexNormals(aiMesh *pMesh, unsigned int m
         const aiVector3D *pV1 = &pMesh->mVertices[face.mIndices[0]];
         const aiVector3D *pV2 = &pMesh->mVertices[face.mIndices[1]];
         const aiVector3D *pV3 = &pMesh->mVertices[face.mIndices[face.mNumIndices - 1]];
+        if (flippedWindingOrder_)
+            std::swap( pV2, pV3 );
         const aiVector3D vNor = ((*pV2 - *pV1) ^ (*pV3 - *pV1)).NormalizeSafe();
 
         for (unsigned int i = 0; i < face.mNumIndices; ++i) {
diff --git a/code/PostProcessing/GenVertexNormalsProcess.h b/code/PostProcessing/GenVertexNormalsProcess.h
index 8b98ea8e6..8fc301ab7 100644
--- a/code/PostProcessing/GenVertexNormalsProcess.h
+++ b/code/PostProcessing/GenVertexNormalsProcess.h
@@ -104,6 +104,7 @@ private:
     /** Configuration option: maximum smoothing angle, in radians*/
     ai_real configMaxAngle;
     mutable bool force_ = false;
+    mutable bool flippedWindingOrder_ = false;
 };
 
 } // end of namespace Assimp
diff --git a/code/PostProcessing/ImproveCacheLocality.cpp b/code/PostProcessing/ImproveCacheLocality.cpp
index 38d5c5a5b..3243c40b4 100644
--- a/code/PostProcessing/ImproveCacheLocality.cpp
+++ b/code/PostProcessing/ImproveCacheLocality.cpp
@@ -109,7 +109,7 @@ void ImproveCacheLocalityProcess::Execute( aiScene* pScene) {
     }
     if (!DefaultLogger::isNullLogger()) {
         if (numf > 0) {
-            ASSIMP_LOG_INFO_F("Cache relevant are ", numm, " meshes (", numf, " faces). Average output ACMR is ", out / numf);
+            ASSIMP_LOG_INFO("Cache relevant are ", numm, " meshes (", numf, " faces). Average output ACMR is ", out / numf);
         }
         ASSIMP_LOG_DEBUG("ImproveCacheLocalityProcess finished. ");
     }
@@ -355,7 +355,7 @@ ai_real ImproveCacheLocalityProcess::ProcessMesh( aiMesh* pMesh, unsigned int me
 
         // very intense verbose logging ... prepare for much text if there are many meshes
         if ( DefaultLogger::get()->getLogSeverity() == Logger::VERBOSE) {
-            ASSIMP_LOG_VERBOSE_DEBUG_F("Mesh %u | ACMR in: ", meshNum, " out: ", fACMR, " | ~", fACMR2, ((fACMR - fACMR2) / fACMR) * 100.f);
+            ASSIMP_LOG_VERBOSE_DEBUG("Mesh %u | ACMR in: ", meshNum, " out: ", fACMR, " | ~", fACMR2, ((fACMR - fACMR2) / fACMR) * 100.f);
         }
 
         fACMR2 *= pMesh->mNumFaces;
diff --git a/code/PostProcessing/JoinVerticesProcess.cpp b/code/PostProcessing/JoinVerticesProcess.cpp
index 22b399471..60c64f3bf 100644
--- a/code/PostProcessing/JoinVerticesProcess.cpp
+++ b/code/PostProcessing/JoinVerticesProcess.cpp
@@ -100,7 +100,7 @@ void JoinVerticesProcess::Execute( aiScene* pScene)
         if (iNumOldVertices == iNumVertices) {
             ASSIMP_LOG_DEBUG("JoinVerticesProcess finished ");
         } else {
-            ASSIMP_LOG_INFO_F("JoinVerticesProcess finished | Verts in: ", iNumOldVertices,
+            ASSIMP_LOG_INFO("JoinVerticesProcess finished | Verts in: ", iNumOldVertices,
                 " out: ", iNumVertices, " | ~",
                 ((iNumOldVertices - iNumVertices) / (float)iNumOldVertices) * 100.f );
         }
@@ -373,7 +373,7 @@ int JoinVerticesProcess::ProcessMesh( aiMesh* pMesh, unsigned int meshIndex)
     }
 
     if (!DefaultLogger::isNullLogger() && DefaultLogger::get()->getLogSeverity() == Logger::VERBOSE)    {
-        ASSIMP_LOG_VERBOSE_DEBUG_F(
+        ASSIMP_LOG_VERBOSE_DEBUG(
             "Mesh ",meshIndex,
             " (",
             (pMesh->mName.length ? pMesh->mName.data : "unnamed"),
diff --git a/code/PostProcessing/LimitBoneWeightsProcess.cpp b/code/PostProcessing/LimitBoneWeightsProcess.cpp
index c7ecf1b00..fb8b49b91 100644
--- a/code/PostProcessing/LimitBoneWeightsProcess.cpp
+++ b/code/PostProcessing/LimitBoneWeightsProcess.cpp
@@ -191,6 +191,6 @@ void LimitBoneWeightsProcess::ProcessMesh(aiMesh* pMesh)
     pMesh->mNumBones = writeBone;
 
     if (!DefaultLogger::isNullLogger()) {
-        ASSIMP_LOG_INFO_F("Removed ", removed, " weights. Input bones: ", old_bones, ". Output bones: ", pMesh->mNumBones);
+        ASSIMP_LOG_INFO("Removed ", removed, " weights. Input bones: ", old_bones, ". Output bones: ", pMesh->mNumBones);
     }
 }
diff --git a/code/PostProcessing/OptimizeGraph.cpp b/code/PostProcessing/OptimizeGraph.cpp
index ad49b635a..e33c2ab18 100644
--- a/code/PostProcessing/OptimizeGraph.cpp
+++ b/code/PostProcessing/OptimizeGraph.cpp
@@ -335,7 +335,7 @@ void OptimizeGraphProcess::Execute(aiScene *pScene) {
 	pScene->mRootNode->mParent = nullptr;
 	if (!DefaultLogger::isNullLogger()) {
 		if (nodes_in != nodes_out) {
-			ASSIMP_LOG_INFO_F("OptimizeGraphProcess finished; Input nodes: ", nodes_in, ", Output nodes: ", nodes_out);
+			ASSIMP_LOG_INFO("OptimizeGraphProcess finished; Input nodes: ", nodes_in, ", Output nodes: ", nodes_out);
 		} else {
 			ASSIMP_LOG_DEBUG("OptimizeGraphProcess finished");
 		}
diff --git a/code/PostProcessing/OptimizeMeshes.cpp b/code/PostProcessing/OptimizeMeshes.cpp
index dd81644de..939284ee4 100644
--- a/code/PostProcessing/OptimizeMeshes.cpp
+++ b/code/PostProcessing/OptimizeMeshes.cpp
@@ -151,7 +151,7 @@ void OptimizeMeshesProcess::Execute( aiScene* pScene)
     std::copy(output.begin(),output.end(),mScene->mMeshes);
 
     if (output.size() != num_old) {
-        ASSIMP_LOG_DEBUG_F("OptimizeMeshesProcess finished. Input meshes: ", num_old, ", Output meshes: ", pScene->mNumMeshes);
+        ASSIMP_LOG_DEBUG("OptimizeMeshesProcess finished. Input meshes: ", num_old, ", Output meshes: ", pScene->mNumMeshes);
     } else {
         ASSIMP_LOG_DEBUG( "OptimizeMeshesProcess finished" );
     }
diff --git a/code/PostProcessing/PretransformVertices.cpp b/code/PostProcessing/PretransformVertices.cpp
index d1740f30b..e9a3af0d2 100644
--- a/code/PostProcessing/PretransformVertices.cpp
+++ b/code/PostProcessing/PretransformVertices.cpp
@@ -429,7 +429,7 @@ void PretransformVertices::Execute(aiScene *pScene) {
 	const unsigned int iOldNodes = CountNodes(pScene->mRootNode);
 
 	if (configTransform) {
-		pScene->mRootNode->mTransformation = configTransformation;
+		pScene->mRootNode->mTransformation = configTransformation * pScene->mRootNode->mTransformation;
 	}
 
 	// first compute absolute transformation matrices for all nodes
@@ -680,9 +680,9 @@ void PretransformVertices::Execute(aiScene *pScene) {
 	if (!DefaultLogger::isNullLogger()) {
 		ASSIMP_LOG_DEBUG("PretransformVerticesProcess finished");
 
-		ASSIMP_LOG_INFO_F("Removed ", iOldNodes, " nodes and ", iOldAnimationChannels, " animation channels (",
+		ASSIMP_LOG_INFO("Removed ", iOldNodes, " nodes and ", iOldAnimationChannels, " animation channels (",
 				CountNodes(pScene->mRootNode), " output nodes)");
-		ASSIMP_LOG_INFO_F("Kept ", pScene->mNumLights, " lights and ", pScene->mNumCameras, " cameras.");
-		ASSIMP_LOG_INFO_F("Moved ", iOldMeshes, " meshes to WCS (number of output meshes: ", pScene->mNumMeshes, ")");
+		ASSIMP_LOG_INFO("Kept ", pScene->mNumLights, " lights and ", pScene->mNumCameras, " cameras.");
+		ASSIMP_LOG_INFO("Moved ", iOldMeshes, " meshes to WCS (number of output meshes: ", pScene->mNumMeshes, ")");
 	}
 }
diff --git a/code/PostProcessing/RemoveRedundantMaterials.cpp b/code/PostProcessing/RemoveRedundantMaterials.cpp
index 5264d3608..c252f37a5 100644
--- a/code/PostProcessing/RemoveRedundantMaterials.cpp
+++ b/code/PostProcessing/RemoveRedundantMaterials.cpp
@@ -122,7 +122,7 @@ void RemoveRedundantMatsProcess::Execute( aiScene* pScene)
 
                         // Keep this material even if no mesh references it
                         abReferenced[i] = true;
-                        ASSIMP_LOG_VERBOSE_DEBUG_F( "Found positive match in exclusion list: \'", name.data, "\'");
+                        ASSIMP_LOG_VERBOSE_DEBUG( "Found positive match in exclusion list: \'", name.data, "\'");
                     }
                 }
             }
@@ -215,7 +215,7 @@ void RemoveRedundantMatsProcess::Execute( aiScene* pScene)
     }
     else
     {
-        ASSIMP_LOG_INFO_F("RemoveRedundantMatsProcess finished. Removed ", redundantRemoved, " redundant and ", 
+        ASSIMP_LOG_INFO("RemoveRedundantMatsProcess finished. Removed ", redundantRemoved, " redundant and ", 
             unreferencedRemoved, " unused materials.");
     }
 }
diff --git a/code/PostProcessing/RemoveRedundantMaterials.h b/code/PostProcessing/RemoveRedundantMaterials.h
index 6b4f8b1fb..4210a7fe2 100644
--- a/code/PostProcessing/RemoveRedundantMaterials.h
+++ b/code/PostProcessing/RemoveRedundantMaterials.h
@@ -81,7 +81,7 @@ public:
     /** @brief Set list of fixed (inmutable) materials
      *  @param fixed See #AI_CONFIG_PP_RRM_EXCLUDE_LIST
      */
-    void SetFixedMaterialsString(const std::string& fixed = "") {
+    void SetFixedMaterialsString(const std::string& fixed = std::string()) {
         mConfigFixedMaterials = fixed;
     }
 
diff --git a/code/PostProcessing/SplitByBoneCountProcess.cpp b/code/PostProcessing/SplitByBoneCountProcess.cpp
index 1f4170a6a..2613d8561 100644
--- a/code/PostProcessing/SplitByBoneCountProcess.cpp
+++ b/code/PostProcessing/SplitByBoneCountProcess.cpp
@@ -103,7 +103,7 @@ void SplitByBoneCountProcess::Execute( aiScene* pScene)
 
     if( !isNecessary )
     {
-        ASSIMP_LOG_DEBUG( format() << "SplitByBoneCountProcess early-out: no meshes with more than " << mMaxBoneCount << " bones." );
+        ASSIMP_LOG_DEBUG("SplitByBoneCountProcess early-out: no meshes with more than ", mMaxBoneCount, " bones." );
         return;
     }
 
@@ -151,7 +151,7 @@ void SplitByBoneCountProcess::Execute( aiScene* pScene)
     // recurse through all nodes and translate the node's mesh indices to fit the new mesh array
     UpdateNode( pScene->mRootNode);
 
-    ASSIMP_LOG_DEBUG( format() << "SplitByBoneCountProcess end: split " << mSubMeshIndices.size() << " meshes into " << meshes.size() << " submeshes." );
+    ASSIMP_LOG_DEBUG( "SplitByBoneCountProcess end: split ", mSubMeshIndices.size(), " meshes into ", meshes.size(), " submeshes." );
 }
 
 // ------------------------------------------------------------------------------------------------
diff --git a/code/PostProcessing/TextureTransform.cpp b/code/PostProcessing/TextureTransform.cpp
index a2f20a082..681b047c0 100644
--- a/code/PostProcessing/TextureTransform.cpp
+++ b/code/PostProcessing/TextureTransform.cpp
@@ -108,7 +108,7 @@ void TextureTransformStep::PreProcessUVTransform(STransformVecInfo& info)
         if (rounded)
         {
             out -= rounded * static_cast<float>(AI_MATH_PI);
-            ASSIMP_LOG_INFO_F("Texture coordinate rotation ", info.mRotation, " can be simplified to ", out);
+            ASSIMP_LOG_INFO("Texture coordinate rotation ", info.mRotation, " can be simplified to ", out);
         }
 
         // Next step - convert negative rotation angles to positives
@@ -448,7 +448,7 @@ void TextureTransformStep::Execute( aiScene* pScene)
         if (size > AI_MAX_NUMBER_OF_TEXTURECOORDS) {
 
             if (!DefaultLogger::isNullLogger()) {
-                ASSIMP_LOG_ERROR_F(static_cast<unsigned int>(trafo.size()), " UV channels required but just ", 
+                ASSIMP_LOG_ERROR(static_cast<unsigned int>(trafo.size()), " UV channels required but just ", 
                     AI_MAX_NUMBER_OF_TEXTURECOORDS, " available");
             }
             size = AI_MAX_NUMBER_OF_TEXTURECOORDS;
@@ -557,7 +557,7 @@ void TextureTransformStep::Execute( aiScene* pScene)
     if (!DefaultLogger::isNullLogger()) {
 
         if (transformedChannels)    {
-            ASSIMP_LOG_INFO_F("TransformUVCoordsProcess end: ", outChannels, " output channels (in: ", inChannels, ", modified: ", transformedChannels,")");
+            ASSIMP_LOG_INFO("TransformUVCoordsProcess end: ", outChannels, " output channels (in: ", inChannels, ", modified: ", transformedChannels,")");
         } else {
             ASSIMP_LOG_DEBUG("TransformUVCoordsProcess finished");
         }
diff --git a/code/PostProcessing/ValidateDataStructure.cpp b/code/PostProcessing/ValidateDataStructure.cpp
index 3058ca6ce..6a872ef11 100644
--- a/code/PostProcessing/ValidateDataStructure.cpp
+++ b/code/PostProcessing/ValidateDataStructure.cpp
@@ -99,7 +99,7 @@ void ValidateDSProcess::ReportWarning(const char *msg, ...) {
     ai_assert(iLen > 0);
 
     va_end(args);
-    ASSIMP_LOG_WARN("Validation warning: " + std::string(szBuffer, iLen));
+    ASSIMP_LOG_WARN("Validation warning: ", std::string(szBuffer, iLen));
 }
 
 // ------------------------------------------------------------------------------------------------
diff --git a/contrib/draco/src/draco/io/parser_utils.cc b/contrib/draco/src/draco/io/parser_utils.cc
index 753a1b314..4f95f6f84 100644
--- a/contrib/draco/src/draco/io/parser_utils.cc
+++ b/contrib/draco/src/draco/io/parser_utils.cc
@@ -252,7 +252,7 @@ DecoderBuffer ParseLineIntoDecoderBuffer(DecoderBuffer *buffer) {
 
 std::string ToLower(const std::string &str) {
   std::string out;
-  std::transform(str.begin(), str.end(), std::back_inserter(out), tolower);
+  std::transform(str.begin(), str.end(), std::back_inserter(out), [](unsigned char c){return tolower(c);});
   return out;
 }
 
diff --git a/contrib/draco/src/draco/io/ply_reader.cc b/contrib/draco/src/draco/io/ply_reader.cc
index ea7f2689a..cb32df225 100644
--- a/contrib/draco/src/draco/io/ply_reader.cc
+++ b/contrib/draco/src/draco/io/ply_reader.cc
@@ -268,14 +268,14 @@ std::vector<std::string> PlyReader::SplitWords(const std::string &line) {
   while ((end = line.find_first_of(" \t\n\v\f\r", start)) !=
          std::string::npos) {
     const std::string word(line.substr(start, end - start));
-    if (!std::all_of(word.begin(), word.end(), isspace)) {
+    if (!std::all_of(word.begin(), word.end(), [](unsigned char c){return isspace(c);})) {
       output.push_back(word);
     }
     start = end + 1;
   }
 
   const std::string last_word(line.substr(start));
-  if (!std::all_of(last_word.begin(), last_word.end(), isspace)) {
+  if (!std::all_of(last_word.begin(), last_word.end(), [](unsigned char c){return isspace(c);})) {
     output.push_back(last_word);
   }
   return output;
diff --git a/contrib/gtest/include/gtest/internal/gtest-param-util.h b/contrib/gtest/include/gtest/internal/gtest-param-util.h
index 82cab9b02..9d725a433 100644
--- a/contrib/gtest/include/gtest/internal/gtest-param-util.h
+++ b/contrib/gtest/include/gtest/internal/gtest-param-util.h
@@ -644,7 +644,7 @@ class ParameterizedTestCaseInfo : public ParameterizedTestCaseInfoBase {
 
     // Check for invalid characters
     for (std::string::size_type index = 0; index < name.size(); ++index) {
-      if (!isalnum(name[index]) && name[index] != '_')
+      if (!IsAlNum(name[index]) && name[index] != '_')
         return false;
     }
 
diff --git a/contrib/openddlparser/code/OpenDDLParser.cpp b/contrib/openddlparser/code/OpenDDLParser.cpp
index 024c26f41..6a9f802ec 100644
--- a/contrib/openddlparser/code/OpenDDLParser.cpp
+++ b/contrib/openddlparser/code/OpenDDLParser.cpp
@@ -72,13 +72,15 @@ const char *getTypeToken(Value::ValueType type) {
 }
 
 static void logInvalidTokenError(char *in, const std::string &exp, OpenDDLParser::logCallback callback) {
-    std::stringstream stream;
-    stream << "Invalid token \"" << *in << "\""
-           << " expected \"" << exp << "\"" << std::endl;
-    std::string full(in);
-    std::string part(full.substr(0, 50));
-    stream << part;
-    callback(ddl_error_msg, stream.str());
+    if (callback) {
+        std::string full(in);
+        std::string part(full.substr(0, 50));
+        std::stringstream stream;
+        stream << "Invalid token \"" << *in << "\" "
+               << "(expected \"" << exp << "\") "
+               << "in: \"" << part << "\"";
+        callback(ddl_error_msg, stream.str());
+    }
 }
 
 static bool isIntegerType(Value::ValueType integerType) {
@@ -111,26 +113,8 @@ static DDLNode *createDDLNode(Text *id, OpenDDLParser *parser) {
     return node;
 }
 
-static void logMessage(LogSeverity severity, const std::string &msg) {
-    std::string log;
-    if (ddl_debug_msg == severity) {
-        log += "Debug:";
-    } else if (ddl_info_msg == severity) {
-        log += "Info :";
-    } else if (ddl_warn_msg == severity) {
-        log += "Warn :";
-    } else if (ddl_error_msg == severity) {
-        log += "Error:";
-    } else {
-        log += "None :";
-    }
-
-    log += msg;
-    std::cout << log;
-}
-
 OpenDDLParser::OpenDDLParser() :
-        m_logCallback(logMessage),
+        m_logCallback(nullptr),
         m_buffer(),
         m_stack(),
         m_context(nullptr) {
@@ -138,7 +122,7 @@ OpenDDLParser::OpenDDLParser() :
 }
 
 OpenDDLParser::OpenDDLParser(const char *buffer, size_t len) :
-        m_logCallback(&logMessage), m_buffer(), m_context(nullptr) {
+        m_logCallback(nullptr), m_buffer(), m_context(nullptr) {
     if (0 != len) {
         setBuffer(buffer, len);
     }
@@ -149,13 +133,8 @@ OpenDDLParser::~OpenDDLParser() {
 }
 
 void OpenDDLParser::setLogCallback(logCallback callback) {
-    if (nullptr != callback) {
-        // install user-specific log callback
-        m_logCallback = callback;
-    } else {
-        // install default log callback
-        m_logCallback = &logMessage;
-    }
+    // install user-specific log callback; null = no log callback
+    m_logCallback = callback;
 }
 
 OpenDDLParser::logCallback OpenDDLParser::getLogCallback() const {
diff --git a/contrib/zip/.gitignore b/contrib/zip/.gitignore
deleted file mode 100644
index 49b2cb2fd..000000000
--- a/contrib/zip/.gitignore
+++ /dev/null
@@ -1,58 +0,0 @@
-/build/
-/test/build/
-/xcodeproj/
-.vscode/
-
-# Object files
-*.o
-*.ko
-*.obj
-*.elf
-
-# Precompiled Headers
-*.gch
-*.pch
-
-# Libraries
-*.lib
-*.a
-*.la
-*.lo
-
-# Shared objects (inc. Windows DLLs)
-*.dll
-*.so
-*.so.*
-*.dylib
-*.suo
-
-# Executables
-*.exe
-*.out
-*.app
-*.i*86
-*.x86_64
-*.hex
-
-# Temporary
-*.swp
-.DS_Store
-
-# CMake
-CMakeScripts
-*.cmake
-
-# Xcode
-*.build
-*.xcodeproj
-zip.sln
-zip.vcxproj.filters
-zip.vcxproj
-ALL_BUILD.vcxproj.filters
-ALL_BUILD.vcxproj
-CMakeFiles/
-zip.dir/
-test/test.exe.vcxproj.filters
-test/test.exe.vcxproj
-test/test.exe.dir/
-
diff --git a/contrib/zip/CMakeLists.txt b/contrib/zip/CMakeLists.txt
index cdfa94b3b..bba4e7bde 100644
--- a/contrib/zip/CMakeLists.txt
+++ b/contrib/zip/CMakeLists.txt
@@ -1,26 +1,29 @@
-cmake_minimum_required(VERSION 3.10)
+cmake_minimum_required(VERSION 3.4)
 
 project(zip
   LANGUAGES C
-  VERSION "0.1.18")
+  VERSION "0.1.19")
 set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake" ${CMAKE_MODULE_PATH})
-
+set(CMAKE_VERBOSE_MAKEFILE ON)
 option(CMAKE_DISABLE_TESTING "Disable test creation" OFF)
 
-if (MSVC)
-  # Use secure functions by default and suppress warnings about "deprecated" functions
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /D _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES=1")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /D _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES_COUNT=1")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /D _CRT_NONSTDC_NO_WARNINGS=1 /D _CRT_SECURE_NO_WARNINGS=1")
-elseif ("${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR
-        "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" OR
-        "${CMAKE_C_COMPILER_ID}" STREQUAL "AppleClang")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99 -Wall -Wextra -Werror -pedantic")
-endif (MSVC)
-
 # zip
 set(SRC src/miniz.h src/zip.h src/zip.c)
-add_library(${PROJECT_NAME} ${SRC})
+
+# this is the "object library" target: compiles the sources only once
+add_library(OBJLIB OBJECT ${SRC})
+# shared libraries need PIC
+set_property(TARGET OBJLIB PROPERTY POSITION_INDEPENDENT_CODE 1)
+
+# static and shared libraries built from the same object files
+if (BUILD_SHARED_LIBS)
+  add_library(${PROJECT_NAME} SHARED $<TARGET_OBJECTS:OBJLIB>)
+  include(GenerateExportHeader)
+  generate_export_header(${PROJECT_NAME})
+else()
+  add_library(${PROJECT_NAME} STATIC $<TARGET_OBJECTS:OBJLIB>)
+endif()
+
 target_include_directories(${PROJECT_NAME} PUBLIC
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>
   $<INSTALL_INTERFACE:include>
@@ -34,6 +37,17 @@ if (NOT CMAKE_DISABLE_TESTING)
   add_sanitizers(${PROJECT_NAME} ${test_out})
 endif()
 
+if (MSVC)
+  # Use secure functions by default and suppress warnings about "deprecated" functions
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /D _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES=1")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /D _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES_COUNT=1")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /D _CRT_NONSTDC_NO_WARNINGS=1 /D _CRT_SECURE_NO_WARNINGS=1")
+elseif ("${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR
+        "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" OR
+        "${CMAKE_C_COMPILER_ID}" STREQUAL "AppleClang")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu99 -Wall -Wextra -Werror -pedantic -Wno-deprecated")
+endif (MSVC)
+
 ####
 # Installation (https://github.com/forexample/package-example) {
 
diff --git a/contrib/zip/README.md b/contrib/zip/README.md
index bdd0822b6..308327a3f 100644
--- a/contrib/zip/README.md
+++ b/contrib/zip/README.md
@@ -2,7 +2,6 @@
 This is done by hacking awesome [miniz](https://code.google.com/p/miniz) library and layering functions on top of the miniz v1.15 API.
 
 [![Build](https://github.com/kuba--/zip/workflows/build/badge.svg)](https://github.com/kuba--/zip/actions?query=workflow%3Abuild)
-[![Version](https://badge.fury.io/gh/kuba--%2Fzip.svg)](https://github.com/kuba--/zip/releases)
 
 
 # The Idea
@@ -155,10 +154,52 @@ struct zip_t *zip = zip_open("foo.zip", 0, 'r');
 zip_close(zip);
 ```
 
+* Create a new zip archive in memory (stream API).
+
+```c
+char *outbuf = NULL;
+size_t outbufsize = 0;
+
+const char *inbuf = "Append some data here...\0";
+struct zip_t *zip = zip_stream_open(NULL, 0, ZIP_DEFAULT_COMPRESSION_LEVEL, 'w');
+{
+    zip_entry_open(zip, "foo-1.txt");
+    {
+        zip_entry_write(zip, inbuf, strlen(inbuf));
+    }
+    zip_entry_close(zip);
+
+    /* copy compressed stream into outbuf */
+    zip_stream_copy(zip, (void **)&outbuf, &outbufsize);
+}
+zip_stream_close(zip);
+
+free(outbuf);
+```
+
+* Extract a zip entry into a memory (stream API).
+
+```c
+char *buf = NULL;
+ssize_t bufsize = 0;
+
+struct zip_t *zip = zip_stream_open(zipstream, zipstreamsize, 0, 'r');
+{
+    zip_entry_open(zip, "foo-1.txt");
+    {
+        zip_entry_read(zip, (void **)&buf, &bufsize);
+    }
+    zip_entry_close(zip);
+}
+zip_stream_close(zip);
+
+free(buf);
+```
+
 * List of all zip entries
 ```c
 struct zip_t *zip = zip_open("foo.zip", 0, 'r');
-int i, n = zip_total_entries(zip);
+int i, n = zip_entries_total(zip);
 for (i = 0; i < n; ++i) {
     zip_entry_openbyindex(zip, i);
     {
@@ -172,6 +213,49 @@ for (i = 0; i < n; ++i) {
 zip_close(zip);
 ```
 
+* Compress folder (recursively)
+```c
+void zip_walk(struct zip_t *zip, const char *path) {
+    DIR *dir;
+    struct dirent *entry;
+    char fullpath[MAX_PATH];
+    struct stat s;
+
+    memset(fullpath, 0, MAX_PATH);
+    dir = opendir(path);
+    assert(dir);
+
+    while ((entry = readdir(dir))) {
+      // skip "." and ".."
+      if (!strcmp(entry->d_name, ".\0") || !strcmp(entry->d_name, "..\0"))
+        continue;
+
+      snprintf(fullpath, sizeof(fullpath), "%s/%s", path, entry->d_name);
+      stat(fullpath, &s);
+      if (S_ISDIR(s.st_mode))
+        zip_walk(zip, fullpath);
+      else {
+        zip_entry_open(zip, fullpath);
+        zip_entry_fwrite(zip, fullpath);
+        zip_entry_close(zip);
+      }
+    }
+
+    closedir(dir);
+}
+```
+
+* Deletes zip archive entries.
+```c
+char *entries[] = {"unused.txt", "remove.ini", "delete.me"};
+
+struct zip_t *zip = zip_open("foo.zip", 0, 'd');
+{
+    zip_entries_delete(zip, entries, 3);
+}
+zip_close(zip);
+```
+
 # Bindings
 Compile zip library as a dynamic library.
 ```shell
@@ -181,7 +265,7 @@ $ cmake -DBUILD_SHARED_LIBS=true ..
 $ make
 ```
 
-### Go (cgo)
+### [Go](https://golang.org) (cgo)
 ```go
 package main
 
@@ -211,7 +295,7 @@ func main() {
 }
 ```
 
-### Rust (ffi)
+### [Rust](https://www.rust-lang.org) (ffi)
 ```rust
 extern crate libc;
 use std::ffi::CString;
@@ -236,7 +320,7 @@ extern "C" {
 }
 
 fn main() {
-    let path = CString::new("/tmp/test.zip").unwrap();
+    let path = CString::new("/tmp/rust.zip").unwrap();
     let mode: libc::c_char = 'w' as libc::c_char;
 
     let entryname = CString::new("test.txt").unwrap();
@@ -258,7 +342,7 @@ fn main() {
 }
 ```
 
-### Ruby (ffi)
+### [Ruby](http://www.ruby-lang.org) (ffi)
 Install _ffi_ gem.
 ```shell
 $ gem install ffi
@@ -291,7 +375,7 @@ Zip.zip_entry_close(ptr)
 Zip.zip_close(ptr)
 ```
 
-### Python (cffi)
+### [Python](https://www.python.org) (cffi)
 Install _cffi_ package
 ```shell
 $ pip install cffi
@@ -325,7 +409,36 @@ Zip.zip_entry_close(ptr)
 Zip.zip_close(ptr)
 ```
 
-### Ring
+### [Never](https://never-lang.readthedocs.io/) (ffi)
+```never
+extern "libzip.so" func zip_open(zipname: string, level: int, mode: char) -> c_ptr
+extern "libzip.so" func zip_close(zip: c_ptr) -> void
+
+extern "libzip.so" func zip_entry_open(zip: c_ptr, entryname: string) -> int
+extern "libzip.so" func zip_entry_close(zip: c_ptr) -> int
+extern "libzip.so" func zip_entry_write(zip: c_ptr, buf: string, bufsize: int) -> int
+extern "libzip.so" func zip_entry_fwrite(zip: c_ptr, filename: string) -> int
+
+func main() -> int
+{
+    let content = "Test content"
+
+    let zip = zip_open("/tmp/never.zip", 6, 'w');
+
+    zip_entry_open(zip, "test.file");
+    zip_entry_fwrite(zip, "/tmp/test.txt");
+    zip_entry_close(zip);
+
+    zip_entry_open(zip, "test.content");
+    zip_entry_write(zip, content, length(content));
+    zip_entry_close(zip);
+
+    zip_close(zip);
+    0
+}
+```
+
+### [Ring](http://ring-lang.net)
 The language comes with RingZip based on this library
 ```ring
 load "ziplib.ring"
@@ -342,13 +455,15 @@ new Zip {
 }
 ```
 
-# Contribution Rules/Coding Standards
-No need to throw away your coding style, just do your best to follow default clang-format style.
-Apply `clang-format` to the source files before commit:
-```sh
-for file in $(git ls-files | \grep -E '\.(c|h)$' | \grep -v -- '#')
-do
-    clang-format -i $file
-done
-```
+# Check out more cool projects which use this library:
+- [Filament](https://github.com/google/filament): Filament is a real-time physically based rendering engine for Android, iOS, Linux, macOS, Windows, and WebGL. It is designed to be as small as possible and as efficient as possible on Android.
+- [Hermes JS Engine](https://github.com/facebook/hermes): Hermes is a JavaScript engine optimized for fast start-up of React Native apps on Android. It features ahead-of-time static optimization and compact bytecode.
+- [Open Asset Import Library](https://github.com/assimp/assimp): A library to import and export various 3d-model-formats including scene-post-processing to generate missing render data.
+- [PowerToys](https://github.com/microsoft/PowerToys): Set of utilities for power users to tune and streamline their Windows 10 experience for greater productivity.
+- [The Ring Programming Language](https://ring-lang.github.io): Innovative and practical general-purpose multi-paradigm language.
+- [The V Programming Language](https://github.com/vlang/v): Simple, fast, safe, compiled. For developing maintainable software.
+- [TIC-80](https://github.com/nesbox/TIC-80): TIC-80 is a FREE and OPEN SOURCE fantasy computer for making, playing and sharing tiny games.
+- [Urho3D](https://github.com/urho3d/Urho3D): Urho3D is a free lightweight, cross-platform 2D and 3D game engine implemented in C++ and released under the MIT license. Greatly inspired by OGRE and Horde3D.
+- [Vcpkg](https://github.com/microsoft/vcpkg): Vcpkg helps you manage C and C++ libraries on Windows, Linux and MacOS.
+- [and more...](https://grep.app/search?q=kuba--/zip)
 
diff --git a/contrib/zip/src/miniz.h b/contrib/zip/src/miniz.h
index 7570ae929..0a5560b24 100644
--- a/contrib/zip/src/miniz.h
+++ b/contrib/zip/src/miniz.h
@@ -400,7 +400,7 @@ typedef enum {
 #ifndef MINIZ_NO_ZLIB_APIS
 
 // Heap allocation callbacks.
-// Note that mz_alloc_func parameter types purpsosely differ from zlib's:
+// Note that mz_alloc_func parameter types purposely differ from zlib's:
 // items/size is size_t, not unsigned long.
 typedef void *(*mz_alloc_func)(void *opaque, size_t items, size_t size);
 typedef void (*mz_free_func)(void *opaque, void *address);
@@ -2194,7 +2194,8 @@ tinfl_status tinfl_decompress(tinfl_decompressor *r,
             } else
               tree_cur = pTable->m_tree[-tree_cur - 1];
           }
-          tree_cur -= ((rev_code >>= 1) & 1);
+          rev_code >>= 1;
+          tree_cur -= (rev_code & 1);
           pTable->m_tree[-tree_cur - 1] = (mz_int16)sym_index;
         }
         if (r->m_type == 2) {
@@ -3970,6 +3971,7 @@ mz_uint tdefl_create_comp_flags_from_zip_params(int level, int window_bits,
 
 #ifdef _MSC_VER
 #pragma warning(push)
+#pragma warning(disable : 4121 4127 4244)
 #pragma warning(disable : 4204) // nonstandard extension used : non-constant
                                 // aggregate initializer (also supported by GNU
                                 // C and C99, so no big deal)
@@ -4098,10 +4100,6 @@ void *tdefl_write_image_to_png_file_in_memory(const void *pImage, int w, int h,
                                                     pLen_out, 6, MZ_FALSE);
 }
 
-#ifdef _MSC_VER
-#pragma warning(pop)
-#endif
-
 // ------------------- .ZIP archive reading
 
 #ifndef MINIZ_NO_ARCHIVE_APIS
@@ -4112,18 +4110,39 @@ void *tdefl_write_image_to_png_file_in_memory(const void *pImage, int w, int h,
 #include <stdio.h>
 #include <sys/stat.h>
 
-#if defined(_MSC_VER)
+#if defined(_MSC_VER) || defined(__MINGW32__)
+
+#include <windows.h>
+
+static wchar_t *str2wstr(const char *str) {
+  int len = (int) strlen(str) + 1;
+  wchar_t *wstr = malloc(len * sizeof(wchar_t));
+  MultiByteToWideChar(CP_UTF8, 0, str, len * sizeof(char), wstr, len);
+  return wstr;
+}
+
 static FILE *mz_fopen(const char *pFilename, const char *pMode) {
-  FILE *pFile = NULL;
-  fopen_s(&pFile, pFilename, pMode);
+  wchar_t *wFilename = str2wstr(pFilename);
+  wchar_t *wMode = str2wstr(pMode);
+  FILE *pFile = _wfopen(wFilename, wMode);
+
+  free(wFilename);
+  free(wMode);
+
   return pFile;
 }
+
 static FILE *mz_freopen(const char *pPath, const char *pMode, FILE *pStream) {
-  FILE *pFile = NULL;
-  if (freopen_s(&pFile, pPath, pMode, pStream))
-    return NULL;
+  wchar_t *wPath = str2wstr(pPath);
+  wchar_t *wMode = str2wstr(pMode);
+  FILE *pFile = _wfreopen(wPath, wMode, pStream);
+
+  free(wPath);
+  free(wMode);
+
   return pFile;
 }
+
 #ifndef MINIZ_NO_TIME
 #include <sys/utime.h>
 #endif
@@ -4144,7 +4163,7 @@ static FILE *mz_freopen(const char *pPath, const char *pMode, FILE *pStream) {
 #include <sys/utime.h>
 #endif
 #define MZ_FILE FILE
-#define MZ_FOPEN(f, m) fopen(f, m)
+#define MZ_FOPEN(f, m) mz_fopen
 #define MZ_FCLOSE fclose
 #define MZ_FREAD fread
 #define MZ_FWRITE fwrite
@@ -4153,7 +4172,7 @@ static FILE *mz_freopen(const char *pPath, const char *pMode, FILE *pStream) {
 #define MZ_FILE_STAT_STRUCT _stat
 #define MZ_FILE_STAT _stat
 #define MZ_FFLUSH fflush
-#define MZ_FREOPEN(f, m, s) freopen(f, m, s)
+#define MZ_FREOPEN(f, m, s) mz_freopen
 #define MZ_DELETE_FILE remove
 #elif defined(__TINYC__)
 #ifndef MINIZ_NO_TIME
@@ -5361,13 +5380,9 @@ mz_bool mz_zip_reader_extract_to_mem_no_alloc(mz_zip_archive *pZip,
   } else {
     // Temporarily allocate a read buffer.
     read_buf_size = MZ_MIN(file_stat.m_comp_size, MZ_ZIP_MAX_IO_BUF_SIZE);
-#if defined(_MSC_VER) && !defined(__clang__)
-    if (((0, sizeof(size_t) == sizeof(mz_uint32))) &&
-        (read_buf_size > 0x7FFFFFFF))
-#else
     if (((sizeof(size_t) == sizeof(mz_uint32))) && (read_buf_size > 0x7FFFFFFF))
-#endif
       return MZ_FALSE;
+
     if (NULL == (pRead_buf = pZip->m_pAlloc(pZip->m_pAlloc_opaque, 1,
                                             (size_t)read_buf_size)))
       return MZ_FALSE;
@@ -5454,11 +5469,7 @@ void *mz_zip_reader_extract_to_heap(mz_zip_archive *pZip, mz_uint file_index,
   uncomp_size = MZ_READ_LE32(p + MZ_ZIP_CDH_DECOMPRESSED_SIZE_OFS);
 
   alloc_size = (flags & MZ_ZIP_FLAG_COMPRESSED_DATA) ? comp_size : uncomp_size;
-#if defined(_MSC_VER) && !defined(__clang__)
-  if (((0, sizeof(size_t) == sizeof(mz_uint32))) && (alloc_size > 0x7FFFFFFF))
-#else
   if (((sizeof(size_t) == sizeof(mz_uint32))) && (alloc_size > 0x7FFFFFFF))
-#endif
     return NULL;
   if (NULL ==
       (pBuf = pZip->m_pAlloc(pZip->m_pAlloc_opaque, 1, (size_t)alloc_size)))
@@ -5560,14 +5571,10 @@ mz_bool mz_zip_reader_extract_to_callback(mz_zip_archive *pZip,
   if ((flags & MZ_ZIP_FLAG_COMPRESSED_DATA) || (!file_stat.m_method)) {
     // The file is stored or the caller has requested the compressed data.
     if (pZip->m_pState->m_pMem) {
-#if defined (_MSC_VER) && !defined(__clang__)
-      if (((0, sizeof(size_t) == sizeof(mz_uint32))) &&
-          (file_stat.m_comp_size > 0xFFFFFFFF))
-#else
       if (((sizeof(size_t) == sizeof(mz_uint32))) &&
           (file_stat.m_comp_size > 0xFFFFFFFF))
-#endif
         return MZ_FALSE;
+
       if (pCallback(pOpaque, out_buf_ofs, pRead_buf,
                     (size_t)file_stat.m_comp_size) != file_stat.m_comp_size)
         status = TINFL_STATUS_FAILED;
@@ -6085,7 +6092,7 @@ mz_zip_writer_compute_padding_needed_for_file_alignment(mz_zip_archive *pZip) {
   if (!pZip->m_file_offset_alignment)
     return 0;
   n = (mz_uint32)(pZip->m_archive_size & (pZip->m_file_offset_alignment - 1));
-  return (mz_uint)(pZip->m_file_offset_alignment - n) &
+  return (pZip->m_file_offset_alignment - n) &
          (pZip->m_file_offset_alignment - 1);
 }
 
@@ -6289,7 +6296,10 @@ mz_bool mz_zip_writer_add_file(mz_zip_archive *pZip, const char *pArchive_name,
                                mz_uint32 ext_attributes) {
   mz_uint uncomp_crc32 = MZ_CRC32_INIT, level, num_alignment_padding_bytes;
   mz_uint16 method = 0, dos_time = 0, dos_date = 0;
+#ifndef MINIZ_NO_TIME
   time_t file_modified_time;
+#endif
+
   mz_uint64 local_dir_header_ofs, cur_archive_file_ofs, uncomp_size = 0,
                                                         comp_size = 0;
   size_t archive_name_size;
@@ -6326,10 +6336,12 @@ mz_bool mz_zip_writer_add_file(mz_zip_archive *pZip, const char *pArchive_name,
         comment_size + archive_name_size) > 0xFFFFFFFF))
     return MZ_FALSE;
 
+#ifndef MINIZ_NO_TIME
   memset(&file_modified_time, 0, sizeof(file_modified_time));
   if (!mz_zip_get_file_modified_time(pSrc_filename, &file_modified_time))
     return MZ_FALSE;
   mz_zip_time_t_to_dos_time(file_modified_time, &dos_time, &dos_date);
+#endif
 
   pSrc_file = MZ_FOPEN(pSrc_filename, "rb");
   if (!pSrc_file)
@@ -6814,6 +6826,10 @@ void *mz_zip_extract_archive_file_to_heap(const char *pZip_filename,
   return p;
 }
 
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+
 #endif // #ifndef MINIZ_NO_STDIO
 
 #endif // #ifndef MINIZ_NO_ARCHIVE_WRITING_APIS
diff --git a/contrib/zip/src/zip.c b/contrib/zip/src/zip.c
index 83e8e2a41..29af2ec99 100644
--- a/contrib/zip/src/zip.c
+++ b/contrib/zip/src/zip.c
@@ -18,11 +18,6 @@
 /* Win32, DOS, MSVC, MSVS */
 #include <direct.h>
 
-#ifdef _MSC_VER
-#pragma warning(push)
-#pragma warning(disable : 4706)
-#endif // _MSC_VER
-
 #define MKDIR(DIRNAME) _mkdir(DIRNAME)
 #define STRCLONE(STR) ((STR) ? _strdup(STR) : NULL)
 #define HAS_DEVICE(P)                                                          \
@@ -32,17 +27,29 @@
 
 #else
 
-#include <unistd.h> // needed for symlink() on BSD
-int symlink(const char *target, const char *linkpath); // needed on Linux
+#include <unistd.h> // needed for symlink()
 
 #define MKDIR(DIRNAME) mkdir(DIRNAME, 0755)
 #define STRCLONE(STR) ((STR) ? strdup(STR) : NULL)
 
 #endif
 
+#ifdef __MINGW32__
+#include <sys/types.h>
+#include <unistd.h>
+#endif
+
 #include "miniz.h"
 #include "zip.h"
 
+#ifdef _MSC_VER
+#include <io.h>
+#pragma warning(disable : 4706 4244 4028)
+
+#define ftruncate(fd, sz) (-(_chsize_s((fd), (sz)) != 0))
+#define fileno _fileno
+#endif
+
 #ifndef HAS_DEVICE
 #define HAS_DEVICE(P) 0
 #endif
@@ -63,7 +70,84 @@ int symlink(const char *target, const char *linkpath); // needed on Linux
     }                                                                          \
   } while (0)
 
-static const char *base_name(const char *name) {
+struct zip_entry_t {
+  int index;
+  char *name;
+  mz_uint64 uncomp_size;
+  mz_uint64 comp_size;
+  mz_uint32 uncomp_crc32;
+  mz_uint64 offset;
+  mz_uint8 header[MZ_ZIP_LOCAL_DIR_HEADER_SIZE];
+  mz_uint64 header_offset;
+  mz_uint16 method;
+  mz_zip_writer_add_state state;
+  tdefl_compressor comp;
+  mz_uint32 external_attr;
+  time_t m_time;
+};
+
+struct zip_t {
+  mz_zip_archive archive;
+  mz_uint level;
+  struct zip_entry_t entry;
+};
+
+enum zip_modify_t {
+  MZ_KEEP = 0,
+  MZ_DELETE = 1,
+  MZ_MOVE = 2,
+};
+
+struct zip_entry_mark_t {
+  int file_index;
+  enum zip_modify_t type;
+  mz_uint64 m_local_header_ofs;
+  mz_uint64 lf_length;
+};
+
+static const char *const zip_errlist[30] = {
+    NULL,
+    "not initialized\0",
+    "invalid entry name\0",
+    "entry not found\0",
+    "invalid zip mode\0",
+    "invalid compression level\0",
+    "no zip 64 support\0",
+    "memset error\0",
+    "cannot write data to entry\0",
+    "cannot initialize tdefl compressor\0",
+    "invalid index\0",
+    "header not found\0",
+    "cannot flush tdefl buffer\0",
+    "cannot write entry header\0",
+    "cannot create entry header\0",
+    "cannot write to central dir\0",
+    "cannot open file\0",
+    "invalid entry type\0",
+    "extracting data using no memory allocation\0",
+    "file not found\0",
+    "no permission\0",
+    "out of memory\0",
+    "invalid zip archive name\0",
+    "make dir error\0"
+    "symlink error\0"
+    "close archive error\0"
+    "capacity size too small\0",
+    "fseek error\0",
+    "fread error\0",
+    "fwrite error\0",
+};
+
+const char *zip_strerror(int errnum) {
+  errnum = -errnum;
+  if (errnum <= 0 || errnum >= 30) {
+    return NULL;
+  }
+
+  return zip_errlist[errnum];
+}
+
+static const char *zip_basename(const char *name) {
   char const *p;
   char const *base = name += FILESYSTEM_PREFIX_LEN(name);
   int all_slashes = 1;
@@ -82,7 +166,7 @@ static const char *base_name(const char *name) {
   return base;
 }
 
-static int mkpath(char *path) {
+static int zip_mkpath(char *path) {
   char *p;
   char npath[MAX_PATH + 1];
   int len = 0;
@@ -107,7 +191,7 @@ static int mkpath(char *path) {
 
       if (MKDIR(npath) == -1) {
         if (errno != EEXIST) {
-          return -1;
+          return ZIP_EMKDIR;
         }
       }
     }
@@ -117,7 +201,7 @@ static int mkpath(char *path) {
   return 0;
 }
 
-static char *strrpl(const char *str, size_t n, char oldchar, char newchar) {
+static char *zip_strrpl(const char *str, size_t n, char oldchar, char newchar) {
   char c;
   size_t i;
   char *rpl = (char *)calloc((1 + n), sizeof(char));
@@ -136,27 +220,562 @@ static char *strrpl(const char *str, size_t n, char oldchar, char newchar) {
   return begin;
 }
 
-struct zip_entry_t {
-  int index;
-  char *name;
-  mz_uint64 uncomp_size;
-  mz_uint64 comp_size;
-  mz_uint32 uncomp_crc32;
-  mz_uint64 offset;
-  mz_uint8 header[MZ_ZIP_LOCAL_DIR_HEADER_SIZE];
-  mz_uint64 header_offset;
-  mz_uint16 method;
-  mz_zip_writer_add_state state;
-  tdefl_compressor comp;
-  mz_uint32 external_attr;
-  time_t m_time;
-};
+static char *zip_name_normalize(char *name, char *const nname, size_t len) {
+  size_t offn = 0;
+  size_t offnn = 0, ncpy = 0;
 
-struct zip_t {
-  mz_zip_archive archive;
-  mz_uint level;
-  struct zip_entry_t entry;
-};
+  if (name == NULL || nname == NULL || len <= 0) {
+    return NULL;
+  }
+  // skip trailing '/'
+  while (ISSLASH(*name))
+    name++;
+
+  for (; offn < len; offn++) {
+    if (ISSLASH(name[offn])) {
+      if (ncpy > 0 && strcmp(&nname[offnn], ".\0") &&
+          strcmp(&nname[offnn], "..\0")) {
+        offnn += ncpy;
+        nname[offnn++] = name[offn]; // append '/'
+      }
+      ncpy = 0;
+    } else {
+      nname[offnn + ncpy] = name[offn];
+      ncpy++;
+    }
+  }
+
+  // at the end, extra check what we've already copied
+  if (ncpy == 0 || !strcmp(&nname[offnn], ".\0") ||
+      !strcmp(&nname[offnn], "..\0")) {
+    nname[offnn] = 0;
+  }
+  return nname;
+}
+
+static mz_bool zip_name_match(const char *name1, const char *name2) {
+  int len2 = (int) strlen(name2);
+  char *nname2 = zip_strrpl(name2, len2, '\\', '/');
+  if (!nname2) {
+    return MZ_FALSE;
+  }
+
+  mz_bool res = (strcmp(name1, nname2) == 0) ? MZ_TRUE : MZ_FALSE;
+  CLEANUP(nname2);
+  return res;
+}
+
+static int zip_archive_truncate(mz_zip_archive *pzip) {
+  mz_zip_internal_state *pState = pzip->m_pState;
+  mz_uint64 file_size = pzip->m_archive_size;
+  if ((pzip->m_pWrite == mz_zip_heap_write_func) && (pState->m_pMem)) {
+    return 0;
+  }
+  if (pzip->m_zip_mode == MZ_ZIP_MODE_WRITING_HAS_BEEN_FINALIZED) {
+    if (pState->m_pFile) {
+      int fd = fileno(pState->m_pFile);
+      return ftruncate(fd, file_size);
+    }
+  }
+  return 0;
+}
+
+static int zip_archive_extract(mz_zip_archive *zip_archive, const char *dir,
+                               int (*on_extract)(const char *filename,
+                                                 void *arg),
+                               void *arg) {
+  int err = 0;
+  mz_uint i, n;
+  char path[MAX_PATH + 1];
+  char symlink_to[MAX_PATH + 1];
+  mz_zip_archive_file_stat info;
+  size_t dirlen = 0;
+  mz_uint32 xattr = 0;
+
+  memset(path, 0, sizeof(path));
+  memset(symlink_to, 0, sizeof(symlink_to));
+
+  dirlen = strlen(dir);
+  if (dirlen + 1 > MAX_PATH) {
+    return ZIP_EINVENTNAME;
+  }
+
+  memset((void *)&info, 0, sizeof(mz_zip_archive_file_stat));
+
+#if defined(_MSC_VER)
+  strcpy_s(path, MAX_PATH, dir);
+#else
+  strcpy(path, dir);
+#endif
+
+  if (!ISSLASH(path[dirlen - 1])) {
+#if defined(_WIN32) || defined(__WIN32__)
+    path[dirlen] = '\\';
+#else
+    path[dirlen] = '/';
+#endif
+    ++dirlen;
+  }
+
+  // Get and print information about each file in the archive.
+  n = mz_zip_reader_get_num_files(zip_archive);
+  for (i = 0; i < n; ++i) {
+    if (!mz_zip_reader_file_stat(zip_archive, i, &info)) {
+      // Cannot get information about zip archive;
+      err = ZIP_ENOENT;
+      goto out;
+    }
+
+    if (!zip_name_normalize(info.m_filename, info.m_filename,
+                            strlen(info.m_filename))) {
+      // Cannot normalize file name;
+      err = ZIP_EINVENTNAME;
+      goto out;
+    }
+#if defined(_MSC_VER)
+    strncpy_s(&path[dirlen], MAX_PATH - dirlen, info.m_filename,
+              MAX_PATH - dirlen);
+#else
+    strncpy(&path[dirlen], info.m_filename, MAX_PATH - dirlen);
+#endif
+    err = zip_mkpath(path);
+    if (err < 0) {
+      // Cannot make a path
+      goto out;
+    }
+
+    if ((((info.m_version_made_by >> 8) == 3) ||
+         ((info.m_version_made_by >> 8) ==
+          19)) // if zip is produced on Unix or macOS (3 and 19 from
+               // section 4.4.2.2 of zip standard)
+        && info.m_external_attr &
+               (0x20 << 24)) { // and has sym link attribute (0x80 is file, 0x40
+                               // is directory)
+#if defined(_WIN32) || defined(__WIN32__) || defined(_MSC_VER) ||              \
+    defined(__MINGW32__)
+#else
+      if (info.m_uncomp_size > MAX_PATH ||
+          !mz_zip_reader_extract_to_mem_no_alloc(zip_archive, i, symlink_to,
+                                                 MAX_PATH, 0, NULL, 0)) {
+        err = ZIP_EMEMNOALLOC;
+        goto out;
+      }
+      symlink_to[info.m_uncomp_size] = '\0';
+      if (symlink(symlink_to, path) != 0) {
+        err = ZIP_ESYMLINK;
+        goto out;
+      }
+#endif
+    } else {
+      if (!mz_zip_reader_is_file_a_directory(zip_archive, i)) {
+        if (!mz_zip_reader_extract_to_file(zip_archive, i, path, 0)) {
+          // Cannot extract zip archive to file
+          err = ZIP_ENOFILE;
+          goto out;
+        }
+      }
+
+#if defined(_MSC_VER)
+      (void)xattr; // unused
+#else
+      xattr = (info.m_external_attr >> 16) & 0xFFFF;
+      if (xattr > 0) {
+        if (chmod(path, (mode_t)xattr) < 0) {
+          err = ZIP_ENOPERM;
+          goto out;
+        }
+      }
+#endif
+    }
+
+    if (on_extract) {
+      if (on_extract(path, arg) < 0) {
+        goto out;
+      }
+    }
+  }
+
+out:
+  // Close the archive, freeing any resources it was using
+  if (!mz_zip_reader_end(zip_archive)) {
+    // Cannot end zip reader
+    err = ZIP_ECLSZIP;
+  }
+  return err;
+}
+
+static inline void zip_archive_finalize(mz_zip_archive *pzip) {
+  mz_zip_writer_finalize_archive(pzip);
+  zip_archive_truncate(pzip);
+}
+
+static int zip_entry_mark(struct zip_t *zip,
+                          struct zip_entry_mark_t *entry_mark, int n,
+                          char *const entries[], const size_t len) {
+  int err = 0;
+  if (!zip || !entry_mark || !entries) {
+    return ZIP_ENOINIT;
+  }
+
+  mz_zip_archive_file_stat file_stat;
+  mz_uint64 d_pos = (mz_uint64) ~0;
+  for (int i = 0; i < n; ++i) {
+    err = zip_entry_openbyindex(zip, i);
+    if (err) {
+      return err;
+    }
+
+    mz_bool name_matches = MZ_FALSE;
+    for (int j = 0; j < (const int)len; ++j) {
+      if (zip_name_match(zip->entry.name, entries[j])) {
+        name_matches = MZ_TRUE;
+        break;
+      }
+    }
+    if (name_matches) {
+      entry_mark[i].type = MZ_DELETE;
+    } else {
+      entry_mark[i].type = MZ_KEEP;
+    }
+
+    if (!mz_zip_reader_file_stat(&zip->archive, i, &file_stat)) {
+      return ZIP_ENOENT;
+    }
+
+    zip_entry_close(zip);
+
+    entry_mark[i].m_local_header_ofs = file_stat.m_local_header_ofs;
+    entry_mark[i].file_index = -1;
+    entry_mark[i].lf_length = 0;
+    if ((entry_mark[i].type) == MZ_DELETE &&
+        (d_pos > entry_mark[i].m_local_header_ofs)) {
+      d_pos = entry_mark[i].m_local_header_ofs;
+    }
+  }
+  for (int i = 0; i < n; ++i) {
+    if ((entry_mark[i].m_local_header_ofs > d_pos) &&
+        (entry_mark[i].type != MZ_DELETE)) {
+      entry_mark[i].type = MZ_MOVE;
+    }
+  }
+  return err;
+}
+
+static int zip_index_next(mz_uint64 *local_header_ofs_array, int cur_index) {
+  int new_index = 0;
+  for (int i = cur_index - 1; i >= 0; --i) {
+    if (local_header_ofs_array[cur_index] > local_header_ofs_array[i]) {
+      new_index = i + 1;
+      return new_index;
+    }
+  }
+  return new_index;
+}
+
+static int zip_sort(mz_uint64 *local_header_ofs_array, int cur_index) {
+  int nxt_index = zip_index_next(local_header_ofs_array, cur_index);
+
+  if (nxt_index != cur_index) {
+    mz_uint64 temp = local_header_ofs_array[cur_index];
+    for (int i = cur_index; i > nxt_index; i--) {
+      local_header_ofs_array[i] = local_header_ofs_array[i - 1];
+    }
+    local_header_ofs_array[nxt_index] = temp;
+  }
+  return nxt_index;
+}
+
+static int zip_index_update(struct zip_entry_mark_t *entry_mark, int last_index,
+                            int nxt_index) {
+  for (int j = 0; j < last_index; j++) {
+    if (entry_mark[j].file_index >= nxt_index) {
+      entry_mark[j].file_index += 1;
+    }
+  }
+  entry_mark[nxt_index].file_index = last_index;
+  return 0;
+}
+
+static int zip_entry_finalize(struct zip_t *zip,
+                              struct zip_entry_mark_t *entry_mark,
+                              const int n) {
+
+  mz_uint64 *local_header_ofs_array = (mz_uint64 *)calloc(n, sizeof(mz_uint64));
+  if (!local_header_ofs_array) {
+    return ZIP_EOOMEM;
+  }
+
+  for (int i = 0; i < n; ++i) {
+    local_header_ofs_array[i] = entry_mark[i].m_local_header_ofs;
+    int index = zip_sort(local_header_ofs_array, i);
+
+    if (index != i) {
+      zip_index_update(entry_mark, i, index);
+    }
+    entry_mark[i].file_index = index;
+  }
+
+  mz_uint64 *length = (mz_uint64 *)calloc(n, sizeof(mz_uint64));
+  if (!length) {
+    CLEANUP(local_header_ofs_array);
+    return ZIP_EOOMEM;
+  }
+  for (int i = 0; i < n - 1; i++) {
+    length[i] = local_header_ofs_array[i + 1] - local_header_ofs_array[i];
+  }
+  length[n - 1] = zip->archive.m_archive_size - local_header_ofs_array[n - 1];
+
+  for (int i = 0; i < n; i++) {
+    entry_mark[i].lf_length = length[entry_mark[i].file_index];
+  }
+
+  CLEANUP(length);
+  CLEANUP(local_header_ofs_array);
+  return 0;
+}
+
+static int zip_entry_set(struct zip_t *zip, struct zip_entry_mark_t *entry_mark,
+                         int n, char *const entries[], const size_t len) {
+  int err = 0;
+
+  if ((err = zip_entry_mark(zip, entry_mark, n, entries, len)) < 0) {
+    return err;
+  }
+  if ((err = zip_entry_finalize(zip, entry_mark, n)) < 0) {
+    return err;
+  }
+  return 0;
+}
+
+static mz_int64 zip_file_move(MZ_FILE *m_pFile, const mz_uint64 to,
+                              const mz_uint64 from, const mz_uint64 length,
+                              mz_uint8 *move_buf,
+                              const mz_int64 capacity_size) {
+  if ((mz_int64)length > capacity_size) {
+    return ZIP_ECAPSIZE;
+  }
+  if (MZ_FSEEK64(m_pFile, from, SEEK_SET)) {
+    MZ_FCLOSE(m_pFile);
+    return ZIP_EFSEEK;
+  }
+
+  if (fread(move_buf, 1, length, m_pFile) != length) {
+    MZ_FCLOSE(m_pFile);
+    return ZIP_EFREAD;
+  }
+  if (MZ_FSEEK64(m_pFile, to, SEEK_SET)) {
+    MZ_FCLOSE(m_pFile);
+    return ZIP_EFSEEK;
+  }
+  if (fwrite(move_buf, 1, length, m_pFile) != length) {
+    MZ_FCLOSE(m_pFile);
+    return ZIP_EFWRITE;
+  }
+  return (mz_int64)length;
+}
+
+static mz_int64 zip_files_move(MZ_FILE *m_pFile, mz_uint64 writen_num,
+                               mz_uint64 read_num, mz_uint64 length) {
+  int n = 0;
+  const mz_int64 page_size = 1 << 12; // 4K
+  mz_uint8 *move_buf = (mz_uint8 *)calloc(1, page_size);
+  if (move_buf == NULL) {
+    return ZIP_EOOMEM;
+  }
+
+  mz_int64 moved_length = 0;
+  mz_int64 move_count = 0;
+  while ((mz_int64)length > 0) {
+    move_count = ((mz_int64)length >= page_size) ? page_size : (mz_int64)length;
+    n = (int) zip_file_move(m_pFile, writen_num, read_num, move_count, move_buf,
+                      page_size);
+    if (n < 0) {
+      moved_length = n;
+      goto cleanup;
+    }
+
+    if (n != move_count) {
+      goto cleanup;
+    }
+
+    writen_num += move_count;
+    read_num += move_count;
+    length -= move_count;
+    moved_length += move_count;
+  }
+
+cleanup:
+  CLEANUP(move_buf);
+  return moved_length;
+}
+
+static int zip_central_dir_move(mz_zip_internal_state *pState, int begin,
+                                int end, int entry_num) {
+  if (begin == entry_num) {
+    return 0;
+  }
+
+  mz_uint64 l_size = 0;
+  mz_uint64 r_size = 0;
+  mz_uint64 d_size = 0;
+  mz_uint8 *next = NULL;
+  mz_uint8 *deleted = &MZ_ZIP_ARRAY_ELEMENT(
+      &pState->m_central_dir, mz_uint8,
+      MZ_ZIP_ARRAY_ELEMENT(&pState->m_central_dir_offsets, mz_uint32, begin));
+  l_size = (mz_uint32)(deleted - (mz_uint8 *)(pState->m_central_dir.m_p));
+  if (end == entry_num) {
+    r_size = 0;
+  } else {
+    next = &MZ_ZIP_ARRAY_ELEMENT(
+        &pState->m_central_dir, mz_uint8,
+        MZ_ZIP_ARRAY_ELEMENT(&pState->m_central_dir_offsets, mz_uint32, end));
+    r_size = pState->m_central_dir.m_size -
+             (mz_uint32)(next - (mz_uint8 *)(pState->m_central_dir.m_p));
+    d_size = next - deleted;
+  }
+
+  if (l_size == 0) {
+    memmove(pState->m_central_dir.m_p, next, r_size);
+    pState->m_central_dir.m_p = MZ_REALLOC(pState->m_central_dir.m_p, r_size);
+    for (int i = end; i < entry_num; i++) {
+      MZ_ZIP_ARRAY_ELEMENT(&pState->m_central_dir_offsets, mz_uint64, i) -=
+          d_size;
+    }
+  }
+
+  if (l_size * r_size != 0) {
+    memmove(deleted, next, r_size);
+    for (int i = end; i < entry_num; i++) {
+      MZ_ZIP_ARRAY_ELEMENT(&pState->m_central_dir_offsets, mz_uint64, i) -=
+          d_size;
+    }
+  }
+
+  pState->m_central_dir.m_size = l_size + r_size;
+  return 0;
+}
+
+static int zip_central_dir_delete(mz_zip_internal_state *pState,
+                                  int *deleted_entry_index_array,
+                                  int entry_num) {
+  int i = 0;
+  int begin = 0;
+  int end = 0;
+  int d_num = 0;
+  while (i < entry_num) {
+    while ((!deleted_entry_index_array[i]) && (i < entry_num)) {
+      i++;
+    }
+    begin = i;
+
+    while ((deleted_entry_index_array[i]) && (i < entry_num)) {
+      i++;
+    }
+    end = i;
+    zip_central_dir_move(pState, begin, end, entry_num);
+  }
+
+  i = 0;
+  while (i < entry_num) {
+    while ((!deleted_entry_index_array[i]) && (i < entry_num)) {
+      i++;
+    }
+    begin = i;
+    if (begin == entry_num) {
+      break;
+    }
+    while ((deleted_entry_index_array[i]) && (i < entry_num)) {
+      i++;
+    }
+    end = i;
+    int k = 0;
+    for (int j = end; j < entry_num; j++) {
+      MZ_ZIP_ARRAY_ELEMENT(&pState->m_central_dir_offsets, mz_uint32,
+                           begin + k) =
+          (mz_uint32)MZ_ZIP_ARRAY_ELEMENT(&pState->m_central_dir_offsets,
+                                          mz_uint32, j);
+      k++;
+    }
+    d_num += end - begin;
+  }
+
+  pState->m_central_dir_offsets.m_size =
+      sizeof(mz_uint32) * (entry_num - d_num);
+  return 0;
+}
+
+static int zip_entries_delete_mark(struct zip_t *zip,
+                                   struct zip_entry_mark_t *entry_mark,
+                                   int entry_num) {
+  mz_uint64 writen_num = 0;
+  mz_uint64 read_num = 0;
+  mz_uint64 deleted_length = 0;
+  mz_uint64 move_length = 0;
+  int i = 0;
+  int deleted_entry_num = 0;
+  int n = 0;
+
+  mz_bool *deleted_entry_flag_array =
+      (mz_bool *)calloc(entry_num, sizeof(mz_bool));
+  if (deleted_entry_flag_array == NULL) {
+    return ZIP_EOOMEM;
+  }
+
+  mz_zip_internal_state *pState = zip->archive.m_pState;
+  zip->archive.m_zip_mode = MZ_ZIP_MODE_WRITING;
+
+  if (MZ_FSEEK64(pState->m_pFile, 0, SEEK_SET)) {
+    CLEANUP(deleted_entry_flag_array);
+    return ZIP_ENOENT;
+  }
+
+  while (i < entry_num) {
+    while ((entry_mark[i].type == MZ_KEEP) && (i < entry_num)) {
+      writen_num += entry_mark[i].lf_length;
+      read_num = writen_num;
+      i++;
+    }
+
+    while ((entry_mark[i].type == MZ_DELETE) && (i < entry_num)) {
+      deleted_entry_flag_array[i] = MZ_TRUE;
+      read_num += entry_mark[i].lf_length;
+      deleted_length += entry_mark[i].lf_length;
+      i++;
+      deleted_entry_num++;
+    }
+
+    while ((entry_mark[i].type == MZ_MOVE) && (i < entry_num)) {
+      move_length += entry_mark[i].lf_length;
+      mz_uint8 *p = &MZ_ZIP_ARRAY_ELEMENT(
+          &pState->m_central_dir, mz_uint8,
+          MZ_ZIP_ARRAY_ELEMENT(&pState->m_central_dir_offsets, mz_uint32, i));
+      if (!p) {
+        CLEANUP(deleted_entry_flag_array);
+        return ZIP_ENOENT;
+      }
+      mz_uint32 offset = MZ_READ_LE32(p + MZ_ZIP_CDH_LOCAL_HEADER_OFS);
+      offset -= (mz_uint32)deleted_length;
+      MZ_WRITE_LE32(p + MZ_ZIP_CDH_LOCAL_HEADER_OFS, offset);
+      i++;
+    }
+
+    n = (int) zip_files_move(pState->m_pFile, writen_num, read_num, move_length);
+    if (n != (mz_int64)move_length) {
+      CLEANUP(deleted_entry_flag_array);
+      return n;
+    }
+    writen_num += move_length;
+    read_num += move_length;
+  }
+
+  zip->archive.m_archive_size -= deleted_length;
+  zip->archive.m_total_files = entry_num - deleted_entry_num;
+
+  zip_central_dir_delete(pState, deleted_entry_flag_array, entry_num);
+  CLEANUP(deleted_entry_flag_array);
+
+  return deleted_entry_num;
+}
 
 struct zip_t *zip_open(const char *zipname, int level, char mode) {
   struct zip_t *zip = NULL;
@@ -189,6 +808,7 @@ struct zip_t *zip_open(const char *zipname, int level, char mode) {
 
   case 'r':
   case 'a':
+  case 'd':
     if (!mz_zip_reader_init_file(
             &(zip->archive), zipname,
             zip->level | MZ_ZIP_FLAG_DO_NOT_SORT_CENTRAL_DIRECTORY)) {
@@ -196,7 +816,7 @@ struct zip_t *zip_open(const char *zipname, int level, char mode) {
       // zip_archive reader
       goto cleanup;
     }
-    if (mode == 'a' &&
+    if ((mode == 'a' || mode == 'd') &&
         !mz_zip_writer_init_from_reader(&(zip->archive), zipname)) {
       mz_zip_reader_end(&(zip->archive));
       goto cleanup;
@@ -219,7 +839,7 @@ void zip_close(struct zip_t *zip) {
     // Always finalize, even if adding failed for some reason, so we have a
     // valid central directory.
     mz_zip_writer_finalize_archive(&(zip->archive));
-
+    zip_archive_truncate(&(zip->archive));
     mz_zip_writer_end(&(zip->archive));
     mz_zip_reader_end(&(zip->archive));
 
@@ -228,14 +848,9 @@ void zip_close(struct zip_t *zip) {
 }
 
 int zip_is64(struct zip_t *zip) {
-  if (!zip) {
-    // zip_t handler is not initialized
-    return -1;
-  }
-
-  if (!zip->archive.m_pState) {
-    // zip state is not initialized
-    return -1;
+  if (!zip || !zip->archive.m_pState) {
+    // zip_t handler or zip state is not initialized
+    return ZIP_ENOINIT;
   }
 
   return (int)zip->archive.m_pState->m_zip64;
@@ -246,14 +861,19 @@ int zip_entry_open(struct zip_t *zip, const char *entryname) {
   mz_zip_archive *pzip = NULL;
   mz_uint num_alignment_padding_bytes, level;
   mz_zip_archive_file_stat stats;
+  int err = 0;
 
-  if (!zip || !entryname) {
-    return -1;
+  if (!zip) {
+    return ZIP_ENOINIT;
+  }
+
+  if (!entryname) {
+    return ZIP_EINVENTNAME;
   }
 
   entrylen = strlen(entryname);
-  if (entrylen < 1) {
-    return -1;
+  if (entrylen == 0) {
+    return ZIP_EINVENTNAME;
   }
 
   /*
@@ -267,10 +887,13 @@ int zip_entry_open(struct zip_t *zip, const char *entryname) {
     and UNIX file systems etc.  If input came from standard
     input, there is no file name field.
   */
-  zip->entry.name = strrpl(entryname, entrylen, '\\', '/');
+  if (zip->entry.name) {
+    CLEANUP(zip->entry.name);
+  }
+  zip->entry.name = zip_strrpl(entryname, entrylen, '\\', '/');
   if (!zip->entry.name) {
     // Cannot parse zip entry name
-    return -1;
+    return ZIP_EINVENTNAME;
   }
 
   pzip = &(zip->archive);
@@ -278,10 +901,12 @@ int zip_entry_open(struct zip_t *zip, const char *entryname) {
     zip->entry.index =
         mz_zip_reader_locate_file(pzip, zip->entry.name, NULL, 0);
     if (zip->entry.index < 0) {
+      err = ZIP_ENOENT;
       goto cleanup;
     }
 
     if (!mz_zip_reader_file_stat(pzip, (mz_uint)zip->entry.index, &stats)) {
+      err = ZIP_ENOENT;
       goto cleanup;
     }
 
@@ -292,7 +917,9 @@ int zip_entry_open(struct zip_t *zip, const char *entryname) {
     zip->entry.header_offset = stats.m_local_header_ofs;
     zip->entry.method = stats.m_method;
     zip->entry.external_attr = stats.m_external_attr;
+#ifndef MINIZ_NO_TIME
     zip->entry.m_time = stats.m_time;
+#endif
 
     return 0;
   }
@@ -318,11 +945,13 @@ int zip_entry_open(struct zip_t *zip, const char *entryname) {
       mz_zip_writer_compute_padding_needed_for_file_alignment(pzip);
 
   if (!pzip->m_pState || (pzip->m_zip_mode != MZ_ZIP_MODE_WRITING)) {
-    // Wrong zip mode
+    // Invalid zip mode
+    err = ZIP_EINVMODE;
     goto cleanup;
   }
   if (zip->level & MZ_ZIP_FLAG_COMPRESSED_DATA) {
-    // Wrong zip compression level
+    // Invalid zip compression level
+    err = ZIP_EINVLVL;
     goto cleanup;
   }
   // no zip64 support yet
@@ -331,12 +960,14 @@ int zip_entry_open(struct zip_t *zip, const char *entryname) {
         MZ_ZIP_LOCAL_DIR_HEADER_SIZE + MZ_ZIP_CENTRAL_DIR_HEADER_SIZE +
         entrylen) > 0xFFFFFFFF)) {
     // No zip64 support yet
+    err = ZIP_ENOSUP64;
     goto cleanup;
   }
   if (!mz_zip_writer_write_zeros(pzip, zip->entry.offset,
                                  num_alignment_padding_bytes +
                                      sizeof(zip->entry.header))) {
     // Cannot memset zip entry header
+    err = ZIP_EMEMSET;
     goto cleanup;
   }
 
@@ -350,6 +981,7 @@ int zip_entry_open(struct zip_t *zip, const char *entryname) {
   if (pzip->m_pWrite(pzip->m_pIO_opaque, zip->entry.offset, zip->entry.name,
                      entrylen) != entrylen) {
     // Cannot write data to zip entry
+    err = ZIP_EWRTENT;
     goto cleanup;
   }
 
@@ -366,6 +998,7 @@ int zip_entry_open(struct zip_t *zip, const char *entryname) {
                        (int)level, -15, MZ_DEFAULT_STRATEGY)) !=
         TDEFL_STATUS_OKAY) {
       // Cannot initialize the zip compressor
+      err = ZIP_ETDEFLINIT;
       goto cleanup;
     }
   }
@@ -376,7 +1009,7 @@ int zip_entry_open(struct zip_t *zip, const char *entryname) {
 
 cleanup:
   CLEANUP(zip->entry.name);
-  return -1;
+  return err;
 }
 
 int zip_entry_openbyindex(struct zip_t *zip, int index) {
@@ -388,28 +1021,26 @@ int zip_entry_openbyindex(struct zip_t *zip, int index) {
 
   if (!zip) {
     // zip_t handler is not initialized
-    return -1;
+    return ZIP_ENOINIT;
   }
 
   pZip = &(zip->archive);
   if (pZip->m_zip_mode != MZ_ZIP_MODE_READING) {
     // open by index requires readonly mode
-    return -1;
+    return ZIP_EINVMODE;
   }
 
   if (index < 0 || (mz_uint)index >= pZip->m_total_files) {
     // index out of range
-    return -1;
+    return ZIP_EINVIDX;
   }
-
   if (!(pHeader = &MZ_ZIP_ARRAY_ELEMENT(
             &pZip->m_pState->m_central_dir, mz_uint8,
             MZ_ZIP_ARRAY_ELEMENT(&pZip->m_pState->m_central_dir_offsets,
                                  mz_uint32, index)))) {
     // cannot find header in central directory
-    return -1;
+    return ZIP_ENOHDR;
   }
-
   namelen = MZ_READ_LE16(pHeader + MZ_ZIP_CDH_FILENAME_LEN_OFS);
   pFilename = (const char *)pHeader + MZ_ZIP_CENTRAL_DIR_HEADER_SIZE;
 
@@ -424,14 +1055,17 @@ int zip_entry_openbyindex(struct zip_t *zip, int index) {
     and UNIX file systems etc.  If input came from standard
     input, there is no file name field.
   */
-  zip->entry.name = strrpl(pFilename, namelen, '\\', '/');
+  if (zip->entry.name) {
+    CLEANUP(zip->entry.name);
+  }
+  zip->entry.name = zip_strrpl(pFilename, namelen, '\\', '/');
   if (!zip->entry.name) {
     // local entry name is NULL
-    return -1;
+    return ZIP_EINVENTNAME;
   }
 
   if (!mz_zip_reader_file_stat(pZip, (mz_uint)index, &stats)) {
-    return -1;
+    return ZIP_ENOENT;
   }
 
   zip->entry.index = index;
@@ -442,7 +1076,9 @@ int zip_entry_openbyindex(struct zip_t *zip, int index) {
   zip->entry.header_offset = stats.m_local_header_ofs;
   zip->entry.method = stats.m_method;
   zip->entry.external_attr = stats.m_external_attr;
+#ifndef MINIZ_NO_TIME
   zip->entry.m_time = stats.m_time;
+#endif
 
   return 0;
 }
@@ -452,17 +1088,17 @@ int zip_entry_close(struct zip_t *zip) {
   mz_uint level;
   tdefl_status done;
   mz_uint16 entrylen;
-  mz_uint16 dos_time, dos_date;
-  int status = -1;
+  mz_uint16 dos_time = 0, dos_date = 0;
+  int err = 0;
 
   if (!zip) {
     // zip_t handler is not initialized
+    err = ZIP_ENOINIT;
     goto cleanup;
   }
 
   pzip = &(zip->archive);
   if (pzip->m_zip_mode == MZ_ZIP_MODE_READING) {
-    status = 0;
     goto cleanup;
   }
 
@@ -471,6 +1107,7 @@ int zip_entry_close(struct zip_t *zip) {
     done = tdefl_compress_buffer(&(zip->entry.comp), "", 0, TDEFL_FINISH);
     if (done != TDEFL_STATUS_DONE && done != TDEFL_STATUS_OKAY) {
       // Cannot flush compressed buffer
+      err = ZIP_ETDEFLBUF;
       goto cleanup;
     }
     zip->entry.comp_size = zip->entry.state.m_comp_size;
@@ -479,18 +1116,22 @@ int zip_entry_close(struct zip_t *zip) {
   }
 
   entrylen = (mz_uint16)strlen(zip->entry.name);
-  // no zip64 support yet
   if ((zip->entry.comp_size > 0xFFFFFFFF) || (zip->entry.offset > 0xFFFFFFFF)) {
     // No zip64 support, yet
+    err = ZIP_ENOSUP64;
     goto cleanup;
   }
 
+#ifndef MINIZ_NO_TIME
   mz_zip_time_t_to_dos_time(zip->entry.m_time, &dos_time, &dos_date);
+#endif
+
   if (!mz_zip_writer_create_local_dir_header(
           pzip, zip->entry.header, entrylen, 0, zip->entry.uncomp_size,
           zip->entry.comp_size, zip->entry.uncomp_crc32, zip->entry.method, 0,
           dos_time, dos_date)) {
     // Cannot create zip entry header
+    err = ZIP_ECRTHDR;
     goto cleanup;
   }
 
@@ -498,6 +1139,7 @@ int zip_entry_close(struct zip_t *zip) {
                      zip->entry.header,
                      sizeof(zip->entry.header)) != sizeof(zip->entry.header)) {
     // Cannot write zip entry header
+    err = ZIP_EWRTHDR;
     goto cleanup;
   }
 
@@ -507,19 +1149,19 @@ int zip_entry_close(struct zip_t *zip) {
           zip->entry.method, 0, dos_time, dos_date, zip->entry.header_offset,
           zip->entry.external_attr)) {
     // Cannot write to zip central dir
+    err = ZIP_EWRTDIR;
     goto cleanup;
   }
 
   pzip->m_total_files++;
   pzip->m_archive_size = zip->entry.offset;
-  status = 0;
 
 cleanup:
   if (zip) {
     zip->entry.m_time = 0;
     CLEANUP(zip->entry.name);
   }
-  return status;
+  return err;
 }
 
 const char *zip_entry_name(struct zip_t *zip) {
@@ -534,7 +1176,7 @@ const char *zip_entry_name(struct zip_t *zip) {
 int zip_entry_index(struct zip_t *zip) {
   if (!zip) {
     // zip_t handler is not initialized
-    return -1;
+    return ZIP_ENOINIT;
   }
 
   return zip->entry.index;
@@ -543,12 +1185,12 @@ int zip_entry_index(struct zip_t *zip) {
 int zip_entry_isdir(struct zip_t *zip) {
   if (!zip) {
     // zip_t handler is not initialized
-    return -1;
+    return ZIP_ENOINIT;
   }
 
   if (zip->entry.index < 0) {
     // zip entry is not opened
-    return -1;
+    return ZIP_EINVIDX;
   }
 
   return (int)mz_zip_reader_is_file_a_directory(&zip->archive,
@@ -570,7 +1212,7 @@ int zip_entry_write(struct zip_t *zip, const void *buf, size_t bufsize) {
 
   if (!zip) {
     // zip_t handler is not initialized
-    return -1;
+    return ZIP_ENOINIT;
   }
 
   pzip = &(zip->archive);
@@ -584,7 +1226,7 @@ int zip_entry_write(struct zip_t *zip, const void *buf, size_t bufsize) {
       if ((pzip->m_pWrite(pzip->m_pIO_opaque, zip->entry.offset, buf,
                           bufsize) != bufsize)) {
         // Cannot write buffer
-        return -1;
+        return ZIP_EWRTENT;
       }
       zip->entry.offset += bufsize;
       zip->entry.comp_size += bufsize;
@@ -593,7 +1235,7 @@ int zip_entry_write(struct zip_t *zip, const void *buf, size_t bufsize) {
                                      TDEFL_NO_FLUSH);
       if (status != TDEFL_STATUS_DONE && status != TDEFL_STATUS_OKAY) {
         // Cannot compress buffer
-        return -1;
+        return ZIP_ETDEFLBUF;
       }
     }
   }
@@ -602,7 +1244,7 @@ int zip_entry_write(struct zip_t *zip, const void *buf, size_t bufsize) {
 }
 
 int zip_entry_fwrite(struct zip_t *zip, const char *filename) {
-  int status = 0;
+  int err = 0;
   size_t n = 0;
   FILE *stream = NULL;
   mz_uint8 buf[MZ_ZIP_MAX_IO_BUF_SIZE];
@@ -610,14 +1252,14 @@ int zip_entry_fwrite(struct zip_t *zip, const char *filename) {
 
   if (!zip) {
     // zip_t handler is not initialized
-    return -1;
+    return ZIP_ENOINIT;
   }
 
   memset(buf, 0, MZ_ZIP_MAX_IO_BUF_SIZE);
   memset((void *)&file_stat, 0, sizeof(struct MZ_FILE_STAT_STRUCT));
   if (MZ_FILE_STAT(filename, &file_stat) != 0) {
     // problem getting information - check errno
-    return -1;
+    return ZIP_ENOENT;
   }
 
   if ((file_stat.st_mode & 0200) == 0) {
@@ -634,19 +1276,19 @@ int zip_entry_fwrite(struct zip_t *zip, const char *filename) {
 #endif
   {
     // Cannot open filename
-    return -1;
+    return ZIP_EOPNFILE;
   }
 
   while ((n = fread(buf, sizeof(mz_uint8), MZ_ZIP_MAX_IO_BUF_SIZE, stream)) >
          0) {
     if (zip_entry_write(zip, buf, n) < 0) {
-      status = -1;
+      err = ZIP_EWRTENT;
       break;
     }
   }
   fclose(stream);
 
-  return status;
+  return err;
 }
 
 ssize_t zip_entry_read(struct zip_t *zip, void **buf, size_t *bufsize) {
@@ -656,19 +1298,19 @@ ssize_t zip_entry_read(struct zip_t *zip, void **buf, size_t *bufsize) {
 
   if (!zip) {
     // zip_t handler is not initialized
-    return -1;
+    return ZIP_ENOINIT;
   }
 
   pzip = &(zip->archive);
   if (pzip->m_zip_mode != MZ_ZIP_MODE_READING || zip->entry.index < 0) {
     // the entry is not found or we do not have read access
-    return -1;
+    return ZIP_ENOENT;
   }
 
   idx = (mz_uint)zip->entry.index;
   if (mz_zip_reader_is_file_a_directory(pzip, idx)) {
     // the entry is a directory
-    return -1;
+    return ZIP_EINVENTTYPE;
   }
 
   *buf = mz_zip_reader_extract_to_heap(pzip, idx, &size, 0);
@@ -683,18 +1325,18 @@ ssize_t zip_entry_noallocread(struct zip_t *zip, void *buf, size_t bufsize) {
 
   if (!zip) {
     // zip_t handler is not initialized
-    return -1;
+    return ZIP_ENOINIT;
   }
 
   pzip = &(zip->archive);
   if (pzip->m_zip_mode != MZ_ZIP_MODE_READING || zip->entry.index < 0) {
     // the entry is not found or we do not have read access
-    return -1;
+    return ZIP_ENOENT;
   }
 
   if (!mz_zip_reader_extract_to_mem_no_alloc(pzip, (mz_uint)zip->entry.index,
                                              buf, bufsize, 0, NULL, 0)) {
-    return -1;
+    return ZIP_EMEMNOALLOC;
   }
 
   return (ssize_t)zip->entry.uncomp_size;
@@ -703,45 +1345,43 @@ ssize_t zip_entry_noallocread(struct zip_t *zip, void *buf, size_t bufsize) {
 int zip_entry_fread(struct zip_t *zip, const char *filename) {
   mz_zip_archive *pzip = NULL;
   mz_uint idx;
-#if defined(_MSC_VER)
-#else
   mz_uint32 xattr = 0;
-#endif
   mz_zip_archive_file_stat info;
 
   if (!zip) {
     // zip_t handler is not initialized
-    return -1;
+    return ZIP_ENOINIT;
   }
 
   memset((void *)&info, 0, sizeof(mz_zip_archive_file_stat));
   pzip = &(zip->archive);
   if (pzip->m_zip_mode != MZ_ZIP_MODE_READING || zip->entry.index < 0) {
     // the entry is not found or we do not have read access
-    return -1;
+    return ZIP_ENOENT;
   }
 
   idx = (mz_uint)zip->entry.index;
   if (mz_zip_reader_is_file_a_directory(pzip, idx)) {
     // the entry is a directory
-    return -1;
+    return ZIP_EINVENTTYPE;
   }
 
   if (!mz_zip_reader_extract_to_file(pzip, idx, filename, 0)) {
-    return -1;
+    return ZIP_ENOFILE;
   }
 
 #if defined(_MSC_VER)
+  (void)xattr; // unused
 #else
   if (!mz_zip_reader_file_stat(pzip, idx, &info)) {
     // Cannot get information about zip archive;
-    return -1;
+    return ZIP_ENOFILE;
   }
 
   xattr = (info.m_external_attr >> 16) & 0xFFFF;
   if (xattr > 0) {
     if (chmod(filename, (mode_t)xattr) < 0) {
-      return -1;
+      return ZIP_ENOPERM;
     }
   }
 #endif
@@ -758,32 +1398,147 @@ int zip_entry_extract(struct zip_t *zip,
 
   if (!zip) {
     // zip_t handler is not initialized
-    return -1;
+    return ZIP_ENOINIT;
   }
 
   pzip = &(zip->archive);
   if (pzip->m_zip_mode != MZ_ZIP_MODE_READING || zip->entry.index < 0) {
     // the entry is not found or we do not have read access
-    return -1;
+    return ZIP_ENOENT;
   }
 
   idx = (mz_uint)zip->entry.index;
   return (mz_zip_reader_extract_to_callback(pzip, idx, on_extract, arg, 0))
              ? 0
-             : -1;
+             : ZIP_EINVIDX;
 }
 
-int zip_total_entries(struct zip_t *zip) {
+int zip_entries_total(struct zip_t *zip) {
   if (!zip) {
     // zip_t handler is not initialized
-    return -1;
+    return ZIP_ENOINIT;
   }
 
   return (int)zip->archive.m_total_files;
 }
 
+int zip_entries_delete(struct zip_t *zip, char *const entries[],
+                       const size_t len) {
+  int n = 0;
+  int err = 0;
+  struct zip_entry_mark_t *entry_mark = NULL;
+
+  if (zip == NULL || (entries == NULL && len != 0)) {
+    return ZIP_ENOINIT;
+  }
+
+  if (entries == NULL && len == 0) {
+    return 0;
+  }
+
+  n = zip_entries_total(zip);
+
+  entry_mark =
+      (struct zip_entry_mark_t *)calloc(n, sizeof(struct zip_entry_mark_t));
+  if (!entry_mark) {
+    return ZIP_EOOMEM;
+  }
+
+  zip->archive.m_zip_mode = MZ_ZIP_MODE_READING;
+
+  err = zip_entry_set(zip, entry_mark, n, entries, len);
+  if (err < 0) {
+    CLEANUP(entry_mark);
+    return err;
+  }
+
+  err = zip_entries_delete_mark(zip, entry_mark, n);
+  CLEANUP(entry_mark);
+  return err;
+}
+
+int zip_stream_extract(const char *stream, size_t size, const char *dir,
+                       int (*on_extract)(const char *filename, void *arg),
+                       void *arg) {
+  mz_zip_archive zip_archive;
+  if (!stream || !dir) {
+    // Cannot parse zip archive stream
+    return ZIP_ENOINIT;
+  }
+  if (!memset(&zip_archive, 0, sizeof(mz_zip_archive))) {
+    // Cannot memset zip archive
+    return ZIP_EMEMSET;
+  }
+  if (!mz_zip_reader_init_mem(&zip_archive, stream, size, 0)) {
+    // Cannot initialize zip_archive reader
+    return ZIP_ENOINIT;
+  }
+
+  return zip_archive_extract(&zip_archive, dir, on_extract, arg);
+}
+
+struct zip_t *zip_stream_open(const char *stream, size_t size, int level,
+                              char mode) {
+  struct zip_t *zip = (struct zip_t *)calloc((size_t)1, sizeof(struct zip_t));
+  if (!zip) {
+    return NULL;
+  }
+
+  if (level < 0) {
+    level = MZ_DEFAULT_LEVEL;
+  }
+  if ((level & 0xF) > MZ_UBER_COMPRESSION) {
+    // Wrong compression level
+    goto cleanup;
+  }
+  zip->level = (mz_uint)level;
+
+  if ((stream != NULL) && (size > 0) && (mode == 'r')) {
+    if (!mz_zip_reader_init_mem(&(zip->archive), stream, size, 0)) {
+      goto cleanup;
+    }
+  } else if ((stream == NULL) && (size == 0) && (mode == 'w')) {
+    // Create a new archive.
+    if (!mz_zip_writer_init_heap(&(zip->archive), 0, 1024)) {
+      // Cannot initialize zip_archive writer
+      goto cleanup;
+    }
+  } else {
+    goto cleanup;
+  }
+  return zip;
+
+cleanup:
+  CLEANUP(zip);
+  return NULL;
+}
+
+ssize_t zip_stream_copy(struct zip_t *zip, void **buf, ssize_t *bufsize) {
+  if (!zip) {
+    return ZIP_ENOINIT;
+  }
+
+  zip_archive_finalize(&(zip->archive));
+
+  if (bufsize != NULL) {
+    *bufsize = zip->archive.m_archive_size;
+  }
+  *buf = calloc(sizeof(unsigned char), zip->archive.m_archive_size);
+  memcpy(*buf, zip->archive.m_pState->m_pMem, zip->archive.m_archive_size);
+
+  return zip->archive.m_archive_size;
+}
+
+void zip_stream_close(struct zip_t *zip) {
+  if (zip) {
+    mz_zip_writer_end(&(zip->archive));
+    mz_zip_reader_end(&(zip->archive));
+    CLEANUP(zip);
+  }
+}
+
 int zip_create(const char *zipname, const char *filenames[], size_t len) {
-  int status = 0;
+  int err = 0;
   size_t i;
   mz_zip_archive zip_archive;
   struct MZ_FILE_STAT_STRUCT file_stat;
@@ -791,32 +1546,34 @@ int zip_create(const char *zipname, const char *filenames[], size_t len) {
 
   if (!zipname || strlen(zipname) < 1) {
     // zip_t archive name is empty or NULL
-    return -1;
+    return ZIP_EINVZIPNAME;
   }
 
   // Create a new archive.
   if (!memset(&(zip_archive), 0, sizeof(zip_archive))) {
     // Cannot memset zip archive
-    return -1;
+    return ZIP_EMEMSET;
   }
 
   if (!mz_zip_writer_init_file(&zip_archive, zipname, 0)) {
     // Cannot initialize zip_archive writer
-    return -1;
+    return ZIP_ENOINIT;
   }
 
-  memset((void *)&file_stat, 0, sizeof(struct MZ_FILE_STAT_STRUCT));
+  if (!memset((void *)&file_stat, 0, sizeof(struct MZ_FILE_STAT_STRUCT))) {
+    return ZIP_EMEMSET;
+  }
 
   for (i = 0; i < len; ++i) {
     const char *name = filenames[i];
     if (!name) {
-      status = -1;
+      err = ZIP_EINVENTNAME;
       break;
     }
 
     if (MZ_FILE_STAT(name, &file_stat) != 0) {
       // problem getting information - check errno
-      status = -1;
+      err = ZIP_ENOFILE;
       break;
     }
 
@@ -826,150 +1583,39 @@ int zip_create(const char *zipname, const char *filenames[], size_t len) {
     }
     ext_attributes |= (mz_uint32)((file_stat.st_mode & 0xFFFF) << 16);
 
-    if (!mz_zip_writer_add_file(&zip_archive, base_name(name), name, "", 0,
+    if (!mz_zip_writer_add_file(&zip_archive, zip_basename(name), name, "", 0,
                                 ZIP_DEFAULT_COMPRESSION_LEVEL,
                                 ext_attributes)) {
       // Cannot add file to zip_archive
-      status = -1;
+      err = ZIP_ENOFILE;
       break;
     }
   }
 
   mz_zip_writer_finalize_archive(&zip_archive);
   mz_zip_writer_end(&zip_archive);
-  return status;
+  return err;
 }
 
 int zip_extract(const char *zipname, const char *dir,
                 int (*on_extract)(const char *filename, void *arg), void *arg) {
-  int status = -1;
-  mz_uint i, n;
-  char path[MAX_PATH + 1];
-  char symlink_to[MAX_PATH + 1];
   mz_zip_archive zip_archive;
-  mz_zip_archive_file_stat info;
-  size_t dirlen = 0;
-#if defined(_MSC_VER)
-#else
-  mz_uint32 xattr = 0;
-#endif
-
-
-  memset(path, 0, sizeof(path));
-  memset(symlink_to, 0, sizeof(symlink_to));
-  if (!memset(&(zip_archive), 0, sizeof(zip_archive))) {
-    // Cannot memset zip archive
-    return -1;
-  }
 
   if (!zipname || !dir) {
     // Cannot parse zip archive name
-    return -1;
+    return ZIP_EINVZIPNAME;
   }
 
-  dirlen = strlen(dir);
-  if (dirlen + 1 > MAX_PATH) {
-    return -1;
+  if (!memset(&zip_archive, 0, sizeof(mz_zip_archive))) {
+    // Cannot memset zip archive
+    return ZIP_EMEMSET;
   }
 
   // Now try to open the archive.
   if (!mz_zip_reader_init_file(&zip_archive, zipname, 0)) {
     // Cannot initialize zip_archive reader
-    return -1;
+    return ZIP_ENOINIT;
   }
 
-  memset((void *)&info, 0, sizeof(mz_zip_archive_file_stat));
-
-#if defined(_MSC_VER)
-  strcpy_s(path, MAX_PATH, dir);
-#else
-  strcpy(path, dir);
-#endif
-
-  if (!ISSLASH(path[dirlen - 1])) {
-#if defined(_WIN32) || defined(__WIN32__)
-    path[dirlen] = '\\';
-#else
-    path[dirlen] = '/';
-#endif
-    ++dirlen;
-  }
-
-  // Get and print information about each file in the archive.
-  n = mz_zip_reader_get_num_files(&zip_archive);
-  for (i = 0; i < n; ++i) {
-    if (!mz_zip_reader_file_stat(&zip_archive, i, &info)) {
-      // Cannot get information about zip archive;
-      goto out;
-    }
-#if defined(_MSC_VER)
-    strncpy_s(&path[dirlen], MAX_PATH - dirlen, info.m_filename,
-              MAX_PATH - dirlen);
-#else
-    strncpy(&path[dirlen], info.m_filename, MAX_PATH - dirlen);
-#endif
-    if (mkpath(path) < 0) {
-      // Cannot make a path
-      goto out;
-    }
-
-    if ((((info.m_version_made_by >> 8) == 3) ||
-         ((info.m_version_made_by >> 8) ==
-          19)) // if zip is produced on Unix or macOS (3 and 19 from
-               // section 4.4.2.2 of zip standard)
-        && info.m_external_attr &
-               (0x20 << 24)) { // and has sym link attribute (0x80 is file, 0x40
-                               // is directory)
-#if defined(_WIN32) || defined(__WIN32__) || defined(_MSC_VER) ||              \
-    defined(__MINGW32__)
-#else
-      if (info.m_uncomp_size > MAX_PATH ||
-          !mz_zip_reader_extract_to_mem_no_alloc(&zip_archive, i, symlink_to,
-                                                 MAX_PATH, 0, NULL, 0)) {
-        goto out;
-      }
-      symlink_to[info.m_uncomp_size] = '\0';
-      if (symlink(symlink_to, path) != 0) {
-        goto out;
-      }
-#endif
-    } else {
-      if (!mz_zip_reader_is_file_a_directory(&zip_archive, i)) {
-        if (!mz_zip_reader_extract_to_file(&zip_archive, i, path, 0)) {
-          // Cannot extract zip archive to file
-          goto out;
-        }
-      }
-
-#if defined(_MSC_VER)
-#else
-      xattr = (info.m_external_attr >> 16) & 0xFFFF;
-      if (xattr > 0) {
-        if (chmod(path, (mode_t)xattr) < 0) {
-          goto out;
-        }
-      }
-#endif
-    }
-
-    if (on_extract) {
-      if (on_extract(path, arg) < 0) {
-        goto out;
-      }
-    }
-  }
-  status = 0;
-
-out:
-  // Close the archive, freeing any resources it was using
-  if (!mz_zip_reader_end(&zip_archive)) {
-    // Cannot end zip reader
-    status = -1;
-  }
-
-  return status;
+  return zip_archive_extract(&zip_archive, dir, on_extract, arg);
 }
-
-#ifdef _MSC_VER
-#pragma warning(pop)
-#endif // _MSC_VER
diff --git a/contrib/zip/src/zip.h b/contrib/zip/src/zip.h
index 87f3654f4..70ab2cee6 100644
--- a/contrib/zip/src/zip.h
+++ b/contrib/zip/src/zip.h
@@ -15,19 +15,11 @@
 #include <string.h>
 #include <sys/types.h>
 
-#ifdef _MSC_VER
-#pragma warning(push)
-#pragma warning(disable : 4127 )
-#endif //_MSC_VER
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#if !defined(_SSIZE_T_DEFINED) && !defined(_SSIZE_T_DEFINED_) &&               \
-    !defined(__DEFINED_ssize_t) && !defined(__ssize_t_defined) &&              \
-    !defined(_SSIZE_T) && !defined(_SSIZE_T_) && !defined(_SSIZE_T_DECLARED)
-
+#if !defined(_POSIX_C_SOURCE) && defined(_MSC_VER)
 // 64-bit Windows is the only mainstream platform
 // where sizeof(long) != sizeof(void*)
 #ifdef _WIN64
@@ -35,15 +27,6 @@ typedef long long ssize_t; /* byte count or error */
 #else
 typedef long ssize_t; /* byte count or error */
 #endif
-
-#define _SSIZE_T_DEFINED
-#define _SSIZE_T_DEFINED_
-#define __DEFINED_ssize_t
-#define __ssize_t_defined
-#define _SSIZE_T
-#define _SSIZE_T_
-#define _SSIZE_T_DECLARED
-
 #endif
 
 #ifndef MAX_PATH
@@ -64,9 +47,49 @@ typedef long ssize_t; /* byte count or error */
 /**
  * Default zip compression level.
  */
-
 #define ZIP_DEFAULT_COMPRESSION_LEVEL 6
 
+/**
+ * Error codes
+ */
+#define ZIP_ENOINIT -1      // not initialized
+#define ZIP_EINVENTNAME -2  // invalid entry name
+#define ZIP_ENOENT -3       // entry not found
+#define ZIP_EINVMODE -4     // invalid zip mode
+#define ZIP_EINVLVL -5      // invalid compression level
+#define ZIP_ENOSUP64 -6     // no zip 64 support
+#define ZIP_EMEMSET -7      // memset error
+#define ZIP_EWRTENT -8      // cannot write data to entry
+#define ZIP_ETDEFLINIT -9   // cannot initialize tdefl compressor
+#define ZIP_EINVIDX -10     // invalid index
+#define ZIP_ENOHDR -11      // header not found
+#define ZIP_ETDEFLBUF -12   // cannot flush tdefl buffer
+#define ZIP_ECRTHDR -13     // cannot create entry header
+#define ZIP_EWRTHDR -14     // cannot write entry header
+#define ZIP_EWRTDIR -15     // cannot write to central dir
+#define ZIP_EOPNFILE -16    // cannot open file
+#define ZIP_EINVENTTYPE -17 // invalid entry type
+#define ZIP_EMEMNOALLOC -18 // extracting data using no memory allocation
+#define ZIP_ENOFILE -19     // file not found
+#define ZIP_ENOPERM -20     // no permission
+#define ZIP_EOOMEM -21      // out of memory
+#define ZIP_EINVZIPNAME -22 // invalid zip archive name
+#define ZIP_EMKDIR -23      // make dir error
+#define ZIP_ESYMLINK -24    // symlink error
+#define ZIP_ECLSZIP -25     // close archive error
+#define ZIP_ECAPSIZE -26    // capacity size too small
+#define ZIP_EFSEEK -27      // fseek error
+#define ZIP_EFREAD -28      // fread error
+#define ZIP_EFWRITE -29     // fwrite error
+
+/**
+ * Looks up the error message string coresponding to an error number.
+ * @param errnum error number
+ * @return error message string coresponding to errnum or NULL if error is not
+ * found.
+ */
+extern const char *zip_strerror(int errnum);
+
 /**
  * @struct zip_t
  *
@@ -242,8 +265,8 @@ extern ssize_t zip_entry_read(struct zip_t *zip, void **buf, size_t *bufsize);
  *
  * @note ensure supplied output buffer is large enough.
  *       zip_entry_size function (returns uncompressed size for the current
- *       entry) can be handy to estimate how big buffer is needed. for large
- * entries, please take a look at zip_entry_extract function.
+ *       entry) can be handy to estimate how big buffer is needed.
+ *       For large entries, please take a look at zip_entry_extract function.
  *
  * @return the return code - the number of bytes actually read on success.
  *         Otherwise a -1 on error (e.g. bufsize is not large enough).
@@ -285,7 +308,71 @@ zip_entry_extract(struct zip_t *zip,
  * @return the return code - the number of entries on success, negative number
  *         (< 0) on error.
  */
-extern int zip_total_entries(struct zip_t *zip);
+extern int zip_entries_total(struct zip_t *zip);
+
+/**
+ * Deletes zip archive entries.
+ *
+ * @param zip zip archive handler.
+ * @param entries array of zip archive entries to be deleted.
+ * @param len the number of entries to be deleted.
+ * @return the number of deleted entries, or negative number (< 0) on error.
+ */
+extern int zip_entries_delete(struct zip_t *zip, char *const entries[],
+                              size_t len);
+
+/**
+ * Extracts a zip archive stream into directory.
+ *
+ * If on_extract is not NULL, the callback will be called after
+ * successfully extracted each zip entry.
+ * Returning a negative value from the callback will cause abort and return an
+ * error. The last argument (void *arg) is optional, which you can use to pass
+ * data to the on_extract callback.
+ *
+ * @param stream zip archive stream.
+ * @param size stream size.
+ * @param dir output directory.
+ * @param on_extract on extract callback.
+ * @param arg opaque pointer.
+ *
+ * @return the return code - 0 on success, negative number (< 0) on error.
+ */
+extern int zip_stream_extract(const char *stream, size_t size, const char *dir,
+                              int (*on_extract)(const char *filename,
+                                                void *arg),
+                              void *arg);
+
+/**
+ * Opens zip archive stream into memory.
+ *
+ * @param stream zip archive stream.
+ * @param size stream size.
+ *
+ * @return the zip archive handler or NULL on error
+ */
+extern struct zip_t *zip_stream_open(const char *stream, size_t size, int level,
+                                     char mode);
+
+/**
+ * Copy zip archive stream output buffer.
+ *
+ * @param zip zip archive handler.
+ * @param buf output buffer. User should free buf.
+ * @param bufsize output buffer size (in bytes).
+ *
+ * @return copy size
+ */
+extern ssize_t zip_stream_copy(struct zip_t *zip, void **buf, ssize_t *bufsize);
+
+/**
+ * Close zip archive releases resources.
+ *
+ * @param zip zip archive handler.
+ *
+ * @return
+ */
+extern void zip_stream_close(struct zip_t *zip);
 
 /**
  * Creates a new archive and puts files into a single zip archive.
@@ -319,11 +406,6 @@ extern int zip_extract(const char *zipname, const char *dir,
                        void *arg);
 
 /** @} */
-
-#ifdef _MSC_VER
-#pragma warning(pop)
-#endif //_MSC_VER
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/contrib/zip/test/CMakeLists.txt b/contrib/zip/test/CMakeLists.txt
index a7c3650f7..0da1684d4 100644
--- a/contrib/zip/test/CMakeLists.txt
+++ b/contrib/zip/test/CMakeLists.txt
@@ -1,11 +1,38 @@
-cmake_minimum_required(VERSION 3.10)
+cmake_minimum_required(VERSION 3.4)
 
-# test
-set(test_out test.out)
+# tests
+set(test_write_out test_write.out)
+add_executable(${test_write_out} test_write.c)
+target_link_libraries(${test_write_out} zip)
+add_test(NAME ${test_write_out} COMMAND ${test_write_out})
+set(test_write_out ${test_write_out} PARENT_SCOPE)
 
-add_executable(${test_out} test.c)
-target_link_libraries(${test_out} zip)
+set(test_append_out test_append.out)
+add_executable(${test_append_out} test_append.c)
+target_link_libraries(${test_append_out} zip)
+add_test(NAME ${test_append_out} COMMAND ${test_append_out})
+set(test_append_out ${test_append_out} PARENT_SCOPE)
 
-add_test(NAME ${test_out} COMMAND ${test_out})
+set(test_read_out test_read.out)
+add_executable(${test_read_out} test_read.c)
+target_link_libraries(${test_read_out} zip)
+add_test(NAME ${test_read_out} COMMAND ${test_read_out})
+set(test_read_out ${test_read_out} PARENT_SCOPE)
 
-set(test_out ${test_out} PARENT_SCOPE)
+set(test_extract_out test_extract.out)
+add_executable(${test_extract_out} test_extract.c)
+target_link_libraries(${test_extract_out} zip)
+add_test(NAME ${test_extract_out} COMMAND ${test_extract_out})
+set(test_extract_out ${test_extract_out} PARENT_SCOPE)
+
+set(test_entry_out test_entry.out)
+add_executable(${test_entry_out} test_entry.c)
+target_link_libraries(${test_entry_out} zip)
+add_test(NAME ${test_entry_out} COMMAND ${test_entry_out})
+set(test_entry_out ${test_entry_out} PARENT_SCOPE)
+
+set(test_permissions_out test_permissions.out)
+add_executable(${test_permissions_out} test_permissions.c)
+target_link_libraries(${test_permissions_out} zip)
+add_test(NAME ${test_permissions_out} COMMAND ${test_permissions_out})
+set(test_permissions_out ${test_permissions_out} PARENT_SCOPE)
diff --git a/doc/Fileformats.md b/doc/Fileformats.md
index c9116e2e7..89b68e17f 100644
--- a/doc/Fileformats.md
+++ b/doc/Fileformats.md
@@ -81,6 +81,7 @@ __Exporters__:
 - JSON (for WebGl, via https://github.com/acgessler/assimp2json)
 - ASSBIN
 - STEP
+- [PBRTv4](https://github.com/mmp/pbrt-v4)
 - glTF 1.0 (partial)
 - glTF 2.0 (partial)
 - 3MF ( experimental )
diff --git a/include/assimp/BaseImporter.h b/include/assimp/BaseImporter.h
index 86d7ba70f..38bec1afd 100644
--- a/include/assimp/BaseImporter.h
+++ b/include/assimp/BaseImporter.h
@@ -51,10 +51,8 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "Exceptional.h"
 
-#include <assimp/ai_assert.h>
 #include <assimp/types.h>
 #include <assimp/ProgressHandler.hpp>
-#include <map>
 #include <set>
 #include <vector>
 #include <memory>
@@ -179,42 +177,10 @@ public:
     /**
      * Will be called only by scale process when scaling is requested.
      */
-    virtual void SetFileScale(double scale) {
+    void SetFileScale(double scale) {
         fileScale = scale;
     }
 
-    virtual double GetFileScale() const {
-        return fileScale;
-    }
-
-    enum ImporterUnits {
-        M,
-        MM,
-        CM,
-        INCHES,
-        FEET
-    };
-
-    /**
-     * Assimp Importer
-     * unit conversions available 
-     * NOTE: Valid options are initialised in the
-     * constructor in the implementation file to
-     * work around a VS2013 compiler bug if support
-     * for that compiler is dropped in the future
-     * initialisation can be moved back here
-     * */
-    std::map<ImporterUnits, double> importerUnits;
-
-    virtual void SetApplicationUnits(const ImporterUnits &unit) {
-        importerScale = importerUnits[unit];
-        applicationUnits = unit;
-    }
-
-    virtual const ImporterUnits &GetApplicationUnits() {
-        return applicationUnits;
-    }
-
     // -------------------------------------------------------------------
     /** Called by #Importer::GetExtensionList for each loaded importer.
      *  Take the extension list contained in the structure returned by
@@ -223,7 +189,6 @@ public:
     void GetExtensionList(std::set<std::string> &extensions);
 
 protected:
-    ImporterUnits applicationUnits = ImporterUnits::M;
     double importerScale = 1.0;
     double fileScale = 1.0;
 
@@ -420,7 +385,7 @@ public: // static utilities
 
 private:
     /* Pushes state into importer for the importer scale */
-    virtual void UpdateImporterScale(Importer *pImp);
+    void UpdateImporterScale(Importer *pImp);
 
 protected:
     /// Error description in case there was one.
diff --git a/include/assimp/Bitmap.h b/include/assimp/Bitmap.h
index d56bb4c73..e4ce194d9 100644
--- a/include/assimp/Bitmap.h
+++ b/include/assimp/Bitmap.h
@@ -75,13 +75,12 @@ protected:
         uint32_t offset;
 
         // We define the struct size because sizeof(Header) might return a wrong result because of structure padding.
-        // Moreover, we must use this ugly and error prone syntax because Visual Studio neither support constexpr or sizeof(name_of_field).
-        static const std::size_t header_size =
-            sizeof(uint16_t) + // type
-            sizeof(uint32_t) + // size
-            sizeof(uint16_t) + // reserved1
-            sizeof(uint16_t) + // reserved2
-            sizeof(uint32_t);  // offset
+        static constexpr std::size_t header_size =
+            sizeof(type) +
+            sizeof(size) +
+            sizeof(reserved1) +
+            sizeof(reserved2) +
+            sizeof(offset);
     };
 
     struct DIB {
@@ -98,22 +97,21 @@ protected:
         uint32_t nb_important_colors;
 
         // We define the struct size because sizeof(DIB) might return a wrong result because of structure padding.
-        // Moreover, we must use this ugly and error prone syntax because Visual Studio neither support constexpr or sizeof(name_of_field).
-        static const std::size_t dib_size =
-            sizeof(uint32_t) + // size
-            sizeof(int32_t) +  // width
-            sizeof(int32_t) +  // height
-            sizeof(uint16_t) + // planes
-            sizeof(uint16_t) + // bits_per_pixel
-            sizeof(uint32_t) + // compression
-            sizeof(uint32_t) + // image_size
-            sizeof(int32_t) +  // x_resolution
-            sizeof(int32_t) +  // y_resolution
-            sizeof(uint32_t) + // nb_colors
-            sizeof(uint32_t);  // nb_important_colors
+        static constexpr std::size_t dib_size =
+            sizeof(size) +
+            sizeof(width) +
+            sizeof(height) +
+            sizeof(planes) +
+            sizeof(bits_per_pixel) +
+            sizeof(compression) +
+            sizeof(image_size) +
+            sizeof(x_resolution) +
+            sizeof(y_resolution) +
+            sizeof(nb_colors) +
+            sizeof(nb_important_colors);
     };
 
-    static const std::size_t mBytesPerPixel = 4;
+    static constexpr std::size_t mBytesPerPixel = 4;
 
 public:
     static void Save(aiTexture* texture, IOStream* file);
diff --git a/include/assimp/DefaultIOStream.h b/include/assimp/DefaultIOStream.h
index b1bb66902..6d0e13149 100644
--- a/include/assimp/DefaultIOStream.h
+++ b/include/assimp/DefaultIOStream.h
@@ -119,7 +119,7 @@ private:
 AI_FORCE_INLINE
 DefaultIOStream::DefaultIOStream() AI_NO_EXCEPT
 : mFile(nullptr)
-, mFilename("")
+, mFilename()
 , mCachedSize(SIZE_MAX) {
     // empty
 }
diff --git a/include/assimp/Exceptional.h b/include/assimp/Exceptional.h
index 36d60d63a..98e2a3321 100644
--- a/include/assimp/Exceptional.h
+++ b/include/assimp/Exceptional.h
@@ -71,6 +71,9 @@ protected:
  *  nullptr instead of a valid aiScene then.  */
 class ASSIMP_API DeadlyImportError : public DeadlyErrorBase {
 public:
+    DeadlyImportError(const char *message) :
+            DeadlyErrorBase(Assimp::Formatter::format(), std::forward<const char*>(message)) {}
+
     /** Constructor with arguments */
     template<typename... T>
     explicit DeadlyImportError(T&&... args) :
diff --git a/include/assimp/IOSystem.hpp b/include/assimp/IOSystem.hpp
index b05eebce6..76f876440 100644
--- a/include/assimp/IOSystem.hpp
+++ b/include/assimp/IOSystem.hpp
@@ -294,7 +294,7 @@ bool IOSystem::PushDirectory( const std::string &path ) {
 AI_FORCE_INLINE
 const std::string &IOSystem::CurrentDirectory() const {
     if ( m_pathStack.empty() ) {
-        static const std::string Dummy("");
+        static const std::string Dummy;
         return Dummy;
     }
     return m_pathStack[ m_pathStack.size()-1 ];
diff --git a/include/assimp/Importer.hpp b/include/assimp/Importer.hpp
index 18734c302..09b5b6883 100644
--- a/include/assimp/Importer.hpp
+++ b/include/assimp/Importer.hpp
@@ -286,7 +286,7 @@ public:
      * @see GetPropertyInteger()
      */
     std::string GetPropertyString(const char *szName,
-            const std::string &sErrorReturn = "") const;
+            const std::string &sErrorReturn = std::string()) const;
 
     // -------------------------------------------------------------------
     /** Get a matrix configuration property
diff --git a/include/assimp/LineSplitter.h b/include/assimp/LineSplitter.h
index 7cb71476c..44e6f0f1e 100644
--- a/include/assimp/LineSplitter.h
+++ b/include/assimp/LineSplitter.h
@@ -72,7 +72,7 @@ for(LineSplitter splitter(stream);splitter;++splitter) {
        if (strtol(splitter[2]) > 5) { .. }
     }
 
-    ASSIMP_LOG_VERBOSE_DEBUG_F("Current line is: ", splitter.get_index());
+    ASSIMP_LOG_VERBOSE_DEBUG("Current line is: ", splitter.get_index());
 }
 @endcode
 */
diff --git a/include/assimp/LogAux.h b/include/assimp/LogAux.h
index b0a1f9ddd..065433648 100644
--- a/include/assimp/LogAux.h
+++ b/include/assimp/LogAux.h
@@ -64,82 +64,49 @@ public:
     template<typename... T>
     static void ThrowException(T&&... args)
     {
-        throw DeadlyImportError(Prefix(), args...);
+        throw DeadlyImportError(Prefix(), std::forward<T>(args)...);
     }
 
     // ------------------------------------------------------------------------------------------------
-    static void LogWarn(const Formatter::format& message)   {
+    template<typename... T>
+    static void LogWarn(T&&... args) {
         if (!DefaultLogger::isNullLogger()) {
-            ASSIMP_LOG_WARN(Prefix()+(std::string)message);
+            ASSIMP_LOG_WARN(Prefix(), std::forward<T>(args)...);
         }
     }
 
     // ------------------------------------------------------------------------------------------------
-    static void LogError(const Formatter::format& message)  {
+    template<typename... T>
+    static void LogError(T&&... args)  {
         if (!DefaultLogger::isNullLogger()) {
-            ASSIMP_LOG_ERROR(Prefix()+(std::string)message);
+            ASSIMP_LOG_ERROR(Prefix(), std::forward<T>(args)...);
         }
     }
 
     // ------------------------------------------------------------------------------------------------
-    static void LogInfo(const Formatter::format& message)   {
+    template<typename... T>
+    static void LogInfo(T&&... args)  {
         if (!DefaultLogger::isNullLogger()) {
-            ASSIMP_LOG_INFO(Prefix()+(std::string)message);
+            ASSIMP_LOG_INFO(Prefix(), std::forward<T>(args)...);
         }
     }
 
     // ------------------------------------------------------------------------------------------------
-    static void LogDebug(const Formatter::format& message)  {
+    template<typename... T>
+    static void LogDebug(T&&... args)  {
         if (!DefaultLogger::isNullLogger()) {
-            ASSIMP_LOG_DEBUG(Prefix()+(std::string)message);
-        }
-    }
-
-    static void LogVerboseDebug(const Formatter::format& message)  {
-        if (!DefaultLogger::isNullLogger()) {
-            ASSIMP_LOG_VERBOSE_DEBUG(Prefix()+(std::string)message);
-        }
-    }
-
-    // https://sourceforge.net/tracker/?func=detail&atid=1067632&aid=3358562&group_id=226462
-#if !defined(__GNUC__) || !defined(__APPLE__) || __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
-
-    // ------------------------------------------------------------------------------------------------
-    static void LogWarn  (const char* message) {
-        if (!DefaultLogger::isNullLogger()) {
-            LogWarn(Formatter::format(message));
+            ASSIMP_LOG_DEBUG(Prefix(), std::forward<T>(args)...);
         }
     }
 
     // ------------------------------------------------------------------------------------------------
-    static void LogError  (const char* message) {
+    template<typename... T>
+    static void LogVerboseDebug(T&&... args)  {
         if (!DefaultLogger::isNullLogger()) {
-            LogError(Formatter::format(message));
+            ASSIMP_LOG_VERBOSE_DEBUG(Prefix(), std::forward<T>(args)...);
         }
     }
 
-    // ------------------------------------------------------------------------------------------------
-    static void LogInfo  (const char* message) {
-        if (!DefaultLogger::isNullLogger()) {
-            LogInfo(Formatter::format(message));
-        }
-    }
-
-    // ------------------------------------------------------------------------------------------------
-    static void LogDebug  (const char* message) {
-        if (!DefaultLogger::isNullLogger()) {
-            LogDebug(Formatter::format(message));
-        }
-    }
-
-    // ------------------------------------------------------------------------------------------------
-    static void LogVerboseDebug  (const char* message) {
-        if (!DefaultLogger::isNullLogger()) {
-            LogVerboseDebug(Formatter::format(message));
-        }
-    }
-#endif
-
 private:
     static const char* Prefix();
 
diff --git a/include/assimp/Logger.hpp b/include/assimp/Logger.hpp
index ee6eab507..3ca4a6cb2 100644
--- a/include/assimp/Logger.hpp
+++ b/include/assimp/Logger.hpp
@@ -99,34 +99,54 @@ public:
     virtual ~Logger();
 
     // ----------------------------------------------------------------------
-    /** @brief  Writes a debug message
-     *   @param message Debug message*/
+    /** @brief  Writes a info message
+     *  @param  message Info message*/
     void debug(const char* message);
-    void debug(const std::string &message);
+
+    template<typename... T>
+    void debug(T&&... args) {
+        debug(formatMessage(std::forward<T>(args)...).c_str());
+    }
 
     // ----------------------------------------------------------------------
 	/** @brief  Writes a debug message
      *   @param message Debug message*/
-	void verboseDebug(const char *message);
-	void verboseDebug(const std::string &message);
+    void verboseDebug(const char* message);
+    
+    template<typename... T>
+    void verboseDebug(T&&... args) {
+        verboseDebug(formatMessage(std::forward<T>(args)...).c_str());
+    }
 
     // ----------------------------------------------------------------------
     /** @brief  Writes a info message
      *  @param  message Info message*/
     void info(const char* message);
-    void info(const std::string &message);
+
+    template<typename... T>
+    void info(T&&... args) {
+        info(formatMessage(std::forward<T>(args)...).c_str());
+    }
 
     // ----------------------------------------------------------------------
     /** @brief  Writes a warning message
      *  @param  message Warn message*/
     void warn(const char* message);
-    void warn(const std::string &message);
+
+    template<typename... T>
+    void warn(T&&... args) {
+        warn(formatMessage(std::forward<T>(args)...).c_str());
+    }
 
     // ----------------------------------------------------------------------
     /** @brief  Writes an error message
-     *  @param  message Error message*/
+     *  @param  message Info message*/
     void error(const char* message);
-    void error(const std::string &message);
+
+    template<typename... T>
+    void error(T&&... args) {
+        error(formatMessage(std::forward<T>(args)...).c_str());
+    }
 
     // ----------------------------------------------------------------------
     /** @brief  Set a new log severity.
@@ -224,6 +244,15 @@ protected:
      *    the function is left.
      */
     virtual void OnError(const char* message) = 0;
+protected:
+    std::string formatMessage(Assimp::Formatter::format f) {
+        return f;
+    }
+
+    template<typename... T, typename U>
+    std::string formatMessage(Assimp::Formatter::format f, U&& u, T&&... args) {
+        return formatMessage(std::move(f << std::forward<U>(u)), std::forward<T>(args)...);
+    }
 
 protected:
     LogSeverity m_Severity;
@@ -266,66 +295,22 @@ Logger::LogSeverity Logger::getLogSeverity() const {
     return m_Severity;
 }
 
-// ----------------------------------------------------------------------------------
-inline
-void Logger::debug(const std::string &message) {
-    return debug(message.c_str());
-}
-
-// ----------------------------------------------------------------------------------
-inline void Logger::verboseDebug(const std::string &message) {
-	return verboseDebug(message.c_str());
-}
-
-// ----------------------------------------------------------------------------------
-inline
-void Logger::error(const std::string &message) {
-    return error(message.c_str());
-}
-
-// ----------------------------------------------------------------------------------
-inline
-void Logger::warn(const std::string &message) {
-    return warn(message.c_str());
-}
-
-// ----------------------------------------------------------------------------------
-inline
-void Logger::info(const std::string &message) {
-    return info(message.c_str());
-}
-
 } // Namespace Assimp
 
 // ------------------------------------------------------------------------------------------------
-#define ASSIMP_LOG_WARN_F(string, ...) \
-	Assimp::DefaultLogger::get()->warn((Assimp::Formatter::format(string), __VA_ARGS__))
+#define ASSIMP_LOG_WARN(...) \
+	Assimp::DefaultLogger::get()->warn(__VA_ARGS__)
 
-#define ASSIMP_LOG_ERROR_F(string, ...) \
-	Assimp::DefaultLogger::get()->error((Assimp::Formatter::format(string), __VA_ARGS__))
+#define ASSIMP_LOG_ERROR(...) \
+	Assimp::DefaultLogger::get()->error(__VA_ARGS__)
 
-#define ASSIMP_LOG_DEBUG_F(string, ...) \
-	Assimp::DefaultLogger::get()->debug((Assimp::Formatter::format(string), __VA_ARGS__))
+#define ASSIMP_LOG_DEBUG(...) \
+	Assimp::DefaultLogger::get()->debug(__VA_ARGS__)
 
-#define ASSIMP_LOG_VERBOSE_DEBUG_F(string, ...) \
-	Assimp::DefaultLogger::get()->verboseDebug((Assimp::Formatter::format(string), __VA_ARGS__))
+#define ASSIMP_LOG_VERBOSE_DEBUG(...) \
+	Assimp::DefaultLogger::get()->verboseDebug(__VA_ARGS__)
 
-#define ASSIMP_LOG_INFO_F(string, ...) \
-	Assimp::DefaultLogger::get()->info((Assimp::Formatter::format(string), __VA_ARGS__))
-
-#define ASSIMP_LOG_WARN(string) \
-	Assimp::DefaultLogger::get()->warn(string)
-
-#define ASSIMP_LOG_ERROR(string) \
-	Assimp::DefaultLogger::get()->error(string)
-
-#define ASSIMP_LOG_DEBUG(string) \
-	Assimp::DefaultLogger::get()->debug(string)
-
-#define ASSIMP_LOG_VERBOSE_DEBUG(string) \
-	Assimp::DefaultLogger::get()->verboseDebug(string)
-
-#define ASSIMP_LOG_INFO(string) \
-	Assimp::DefaultLogger::get()->info(string)
+#define ASSIMP_LOG_INFO(...) \
+	Assimp::DefaultLogger::get()->info(__VA_ARGS__)
 
 #endif // !! INCLUDED_AI_LOGGER_H
diff --git a/include/assimp/ParsingUtils.h b/include/assimp/ParsingUtils.h
index b52b0610e..b5074869e 100644
--- a/include/assimp/ParsingUtils.h
+++ b/include/assimp/ParsingUtils.h
@@ -262,7 +262,7 @@ AI_FORCE_INLINE unsigned int tokenize(const string_type &str, std::vector<string
 inline std::string ai_stdStrToLower(const std::string &str) {
     std::string out(str);
     for (size_t i = 0; i < str.size(); ++i) {
-        out[i] = (char) tolower(out[i]);
+        out[i] = (char) tolower((unsigned char)out[i]);
     }
     return out;
 }
diff --git a/include/assimp/Profiler.h b/include/assimp/Profiler.h
index 5f9fa52aa..2f2c72bf2 100644
--- a/include/assimp/Profiler.h
+++ b/include/assimp/Profiler.h
@@ -76,7 +76,7 @@ public:
     /** Start a named timer */
     void BeginRegion(const std::string& region) {
         regions[region] = std::chrono::system_clock::now();
-        ASSIMP_LOG_DEBUG((format("START `"),region,"`"));
+        ASSIMP_LOG_DEBUG("START `",region,"`");
     }
 
 
@@ -88,7 +88,7 @@ public:
         }
 
         std::chrono::duration<double> elapsedSeconds = std::chrono::system_clock::now() - regions[region];
-        ASSIMP_LOG_DEBUG((format("END   `"),region,"`, dt= ", elapsedSeconds.count()," s"));
+        ASSIMP_LOG_DEBUG("END   `",region,"`, dt= ", elapsedSeconds.count()," s");
     }
 
 private:
diff --git a/include/assimp/StringComparison.h b/include/assimp/StringComparison.h
index 6dad01294..b0161664f 100644
--- a/include/assimp/StringComparison.h
+++ b/include/assimp/StringComparison.h
@@ -146,8 +146,8 @@ inline int ASSIMP_stricmp(const char *s1, const char *s2) {
 #else
     char c1, c2;
     do {
-        c1 = tolower(*s1++);
-        c2 = tolower(*s2++);
+        c1 = tolower((unsigned char)*(s1++));
+        c2 = tolower((unsigned char)*(s2++));
     } while (c1 && (c1 == c2));
     return c1 - c2;
 #endif
@@ -197,8 +197,8 @@ inline int ASSIMP_strincmp(const char *s1, const char *s2, unsigned int n) {
     unsigned int p = 0;
     do {
         if (p++ >= n) return 0;
-        c1 = tolower(*s1++);
-        c2 = tolower(*s2++);
+        c1 = tolower((unsigned char)*(s1++));
+        c2 = tolower((unsigned char)*(s2++));
     } while (c1 && (c1 == c2));
 
     return c1 - c2;
diff --git a/include/assimp/StringUtils.h b/include/assimp/StringUtils.h
index 4afd717cf..025a826d2 100644
--- a/include/assimp/StringUtils.h
+++ b/include/assimp/StringUtils.h
@@ -4,7 +4,6 @@ Open Asset Import Library (assimp)
 
 Copyright (c) 2006-2021, assimp team
 
-
 All rights reserved.
 
 Redistribution and use of this software in source and binary forms,
@@ -55,6 +54,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <cstdlib>
 #include <locale>
 #include <sstream>
+#include <iomanip>
 
 #ifdef _MSC_VER
 #define AI_SIZEFMT "%Iu"
@@ -157,7 +157,7 @@ AI_FORCE_INLINE std::string ai_decimal_to_hexa(T toConvert) {
     ss >> result;
 
     for (size_t i = 0; i < result.size(); ++i) {
-        result[i] = (char)toupper(result[i]);
+        result[i] = (char)toupper((unsigned char)result[i]);
     }
 
     return result;
@@ -177,7 +177,7 @@ AI_FORCE_INLINE std::string ai_rgba2hex(int r, int g, int b, int a, bool with_he
     if (with_head) {
         ss << "#";
     }
-    ss << std::hex << (r << 24 | g << 16 | b << 8 | a);
+    ss << std::hex << std::setfill('0') << std::setw(8) << (r << 24 | g << 16 | b << 8 | a);
 
     return ss.str();
 }
@@ -249,4 +249,31 @@ AI_FORCE_INLINE std::string ai_str_toupper(const std::string &in) {
     return out;
 }
 
-#endif
+// ---------------------------------------------------------------------------------
+/// @brief  Make a string printable by replacing all non-printable characters with
+///         the specified placeholder character.
+/// @param  in  The incoming string.
+/// @param  placeholder  Placeholder character, default is a question mark.
+/// @return The string, with all non-printable characters replaced.
+AI_FORCE_INLINE std::string ai_str_toprintable(const std::string &in, char placeholder = '?') {
+    std::string out(in);
+    std::transform(out.begin(), out.end(), out.begin(), [placeholder] (unsigned char c) {
+        return isprint(c) ? (char)c :  placeholder;
+    });
+    return out;
+}
+
+// ---------------------------------------------------------------------------------
+/// @brief  Make a string printable by replacing all non-printable characters with
+///         the specified placeholder character.
+/// @param  in  The incoming string.
+/// @param  len The length of the incoming string.
+/// @param  placeholder  Placeholder character, default is a question mark.
+/// @return The string, with all non-printable characters replaced. Will return an
+///         empty string if in is null or len is <= 0.
+AI_FORCE_INLINE std::string ai_str_toprintable(const char *in, int len, char placeholder = '?') {
+    return (in && len > 0) ? ai_str_toprintable(std::string(in, len), placeholder) : std::string();
+}
+
+
+#endif // INCLUDED_AI_STRINGUTILS_H
diff --git a/include/assimp/XmlParser.h b/include/assimp/XmlParser.h
index 15c4ff9ff..18d48f337 100644
--- a/include/assimp/XmlParser.h
+++ b/include/assimp/XmlParser.h
@@ -43,8 +43,11 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define INCLUDED_AI_IRRXML_WRAPPER
 
 #include <assimp/DefaultLogger.hpp>
+#include <assimp/ai_assert.h>
+
 #include "BaseImporter.h"
 #include "IOStream.hpp"
+
 #include <pugixml.hpp>
 #include <vector>
 
@@ -63,6 +66,8 @@ struct find_node_by_name_predicate {
     }
 };
 
+/// @brief  Will convert an attribute to its int value.
+/// @tparam TNodeType The node type.
 template <class TNodeType>
 struct NodeConverter {
 public:
@@ -75,19 +80,37 @@ public:
 using XmlNode = pugi::xml_node;
 using XmlAttribute = pugi::xml_attribute;
 
+/// @brief The Xml-Parser class.
+///
+/// Use this parser if you have to import any kind of xml-format.
+///
+/// An example:
+/// @code
+/// TXmlParser<XmlNode> theParser;
+/// if (theParser.parse(fileStream)) {
+///     auto node = theParser.getRootNode();
+///     for ( auto currentNode : node.children()) {
+///         // Will loop over all children
+///     }
+/// }
+/// @endcode
+/// @tparam TNodeType 
 template <class TNodeType>
 class TXmlParser {
 public:
+    /// @brief The default class constructor.
     TXmlParser() :
             mDoc(nullptr),
             mData() {
         // empty
     }
 
+    ///	@brief  The class destructor.
     ~TXmlParser() {
         clear();
     }
 
+    ///	@brief  Will clear the parsed xml-file.
     void clear() {
         if(mData.empty()) {
             mDoc = nullptr;
@@ -98,6 +121,9 @@ public:
         mDoc = nullptr;
     }
 
+    ///	@brief  Will search for a child-node by its name
+    /// @param  name     [in] The name of the child-node.
+    /// @return The node instance or nullptr, if nothing was found.   
     TNodeType *findNode(const std::string &name) {
         if (name.empty()) {
             return nullptr;
@@ -116,10 +142,16 @@ public:
         return &mCurrent;
     }
 
+    /// @brief  Will return true, if the node is a child-node.
+    /// @param  name    [in] The name of the child node to look for.
+    /// @return true, if the node is a child-node or false if not.
     bool hasNode(const std::string &name) {
         return nullptr != findNode(name);
     }
 
+    /// @brief  Will parse an xml-file from a given stream.
+    /// @param  stream      The input stream.
+    /// @return true, if the parsing was successful, false if not.
     bool parse(IOStream *stream) {
         if (nullptr == stream) {
             ASSIMP_LOG_DEBUG("Stream is nullptr.");
@@ -135,34 +167,67 @@ public:
         pugi::xml_parse_result parse_result = mDoc->load_string(&mData[0], pugi::parse_full);
         if (parse_result.status == pugi::status_ok) {
             return true;
-        } else {
-            ASSIMP_LOG_DEBUG("Error while parse xml.");
-            return false;
-        }
+        } 
+
+        ASSIMP_LOG_DEBUG("Error while parse xml.", std::string(parse_result.description()), " @ ", parse_result.offset);
+
+        return false;
     }
 
+    /// @brief  Will return truem if a root node is there.
+    /// @return true in case of an existing root.
+    bool hasRoot() const {
+        return nullptr != mDoc;
+    }
+    /// @brief  Will return the document pointer, is nullptr if no xml-file was parsed.
+    /// @return The pointer showing to the document.
     pugi::xml_document *getDocument() const {
         return mDoc;
     }
 
+    /// @brief  Will return the root node, const version.
+    /// @return The root node.
     const TNodeType getRootNode() const {
+        static pugi::xml_node none;
+        if (nullptr == mDoc) {
+            return none;
+        }
         return mDoc->root();
     }
 
+    /// @brief  Will return the root node, non-const version.
+    /// @return The root node.
     TNodeType getRootNode() {
+        static pugi::xml_node none;
+        if (nullptr == mDoc) {
+            return none;
+        }
         return mDoc->root();
     }
 
+    /// @brief Will check if a node with the given name is in.
+    /// @param node     [in] The node to look in.
+    /// @param name     [in] The name of the child-node.
+    /// @return true, if node was found, false if not.
     static inline bool hasNode(XmlNode &node, const char *name) {
         pugi::xml_node child = node.find_child(find_node_by_name_predicate(name));
         return !child.empty();
     }
 
+    /// @brief Will check if an attribute is part of the XmlNode.
+    /// @param xmlNode  [in] The node to search in.
+    /// @param name     [in} The attribute name to look for.
+    /// @return true, if the was found, false if not.
     static inline bool hasAttribute(XmlNode &xmlNode, const char *name) {
         pugi::xml_attribute attr = xmlNode.attribute(name);
         return !attr.empty();
     }
 
+    /// @brief Will try to get an unsigned int attribute value.
+    /// @param xmlNode  [in] The node to search in.
+    /// @param name     [in] The attribute name to look for.
+    /// @param val      [out] The unsigned int value from the attribute.
+    /// @return true, if the node contains an attribute with the given name and if the value is an unsigned int.
     static inline bool getUIntAttribute(XmlNode &xmlNode, const char *name, unsigned int &val) {
         pugi::xml_attribute attr = xmlNode.attribute(name);
         if (attr.empty()) {
@@ -173,6 +238,11 @@ public:
         return true;
     }
 
+    /// @brief Will try to get an int attribute value.
+    /// @param xmlNode  [in] The node to search in.
+    /// @param name     [in] The attribute name to look for.
+    /// @param val      [out] The int value from the attribute.
+    /// @return true, if the node contains an attribute with the given name and if the value is an int.
     static inline bool getIntAttribute(XmlNode &xmlNode, const char *name, int &val ) {
         pugi::xml_attribute attr = xmlNode.attribute(name);
         if (attr.empty()) {
@@ -183,6 +253,11 @@ public:
         return true;
     }
 
+    /// @brief Will try to get a real attribute value.
+    /// @param xmlNode  [in] The node to search in.
+    /// @param name     [in] The attribute name to look for.
+    /// @param val      [out] The real value from the attribute.
+    /// @return true, if the node contains an attribute with the given name and if the value is a real.
     static inline bool getRealAttribute( XmlNode &xmlNode, const char *name, ai_real &val ) {
         pugi::xml_attribute attr = xmlNode.attribute(name);
         if (attr.empty()) {
@@ -196,7 +271,12 @@ public:
         return true;
     }
 
-    static inline bool getFloatAttribute(XmlNode &xmlNode, const char *name, float &val ) {
+    /// @brief Will try to get a float attribute value.
+    /// @param xmlNode  [in] The node to search in.
+    /// @param name     [in] The attribute name to look for.
+    /// @param val      [out] The float value from the attribute.
+    /// @return true, if the node contains an attribute with the given name and if the value is a float.
+    static inline bool getFloatAttribute(XmlNode &xmlNode, const char *name, float &val) {
         pugi::xml_attribute attr = xmlNode.attribute(name);
         if (attr.empty()) {
             return false;
@@ -207,7 +287,12 @@ public:
 
     }
 
-    static inline bool getDoubleAttribute( XmlNode &xmlNode, const char *name, double &val ) {
+    /// @brief Will try to get a double attribute value.
+    /// @param xmlNode  [in] The node to search in.
+    /// @param name     [in] The attribute name to look for.
+    /// @param val      [out] The double value from the attribute.
+    /// @return true, if the node contains an attribute with the given name and if the value is a double.
+    static inline bool getDoubleAttribute(XmlNode &xmlNode, const char *name, double &val) {
         pugi::xml_attribute attr = xmlNode.attribute(name);
         if (attr.empty()) {
             return false;
@@ -217,6 +302,11 @@ public:
         return true;
     }
 
+    /// @brief Will try to get a std::string attribute value.
+    /// @param xmlNode  [in] The node to search in.
+    /// @param name     [in] The attribute name to look for.
+    /// @param val      [out] The std::string value from the attribute.
+    /// @return true, if the node contains an attribute with the given name and if the value is a std::string.
     static inline bool getStdStrAttribute(XmlNode &xmlNode, const char *name, std::string &val) {
         pugi::xml_attribute attr = xmlNode.attribute(name);
         if (attr.empty()) {
@@ -227,6 +317,11 @@ public:
         return true;
     }
 
+    /// @brief Will try to get a bool attribute value.
+    /// @param xmlNode  [in] The node to search in.
+    /// @param name     [in] The attribute name to look for.
+    /// @param val      [out] The bool value from the attribute.
+    /// @return true, if the node contains an attribute with the given name and if the value is a bool.
     static inline bool getBoolAttribute( XmlNode &xmlNode, const char *name, bool &val ) {
         pugi::xml_attribute attr = xmlNode.attribute(name);
         if (attr.empty()) {
@@ -238,8 +333,12 @@ public:
 
     }
 
+    /// @brief Will try to get the value of the node as a string.
+    /// @param node     [in] The node to search in.
+    /// @param text     [out] The value as a text.
+    /// @return true, if the value can be read out.
     static inline bool getValueAsString( XmlNode &node, std::string &text ) {
-        text = "";
+        text = std::string();
         if (node.empty()) {
             return false;
         }
@@ -249,6 +348,10 @@ public:
         return true;
     }
 
+    /// @brief Will try to get the value of the node as a float.
+    /// @param node     [in] The node to search in.
+    /// @param text     [out] The value as a float.
+    /// @return true, if the value can be read out.
     static inline bool getValueAsFloat( XmlNode &node, ai_real &v ) {
         if (node.empty()) {
             return false;
@@ -268,17 +371,36 @@ public:
 
 using XmlParser = TXmlParser<pugi::xml_node>;
 
+///	@brief  This class declares an iterator to loop through all children of the root node.
 class XmlNodeIterator {
 public:
-    XmlNodeIterator(XmlNode &parent) :
+    /// @brief The iteration mode.
+    enum IterationMode {
+        PreOrderMode,   ///< Pre-ordering, get the values, continue the iteration.
+        PostOrderMode   ///< Post-ordering, continue the iteration, get the values.
+    };
+    ///	@brief  The class constructor
+    /// @param  parent      [in] The xml parent to to iterate through.
+    /// @param  mode        [in] The iteration mode.
+    explicit XmlNodeIterator(XmlNode &parent, IterationMode mode) :
             mParent(parent),
             mNodes(),
             mIndex(0) {
+        if (mode == PreOrderMode) {
+            collectChildrenPreOrder(parent);
+        } else {
+            collectChildrenPostOrder(parent);
+        }
+    }
+
+    ///	@brief  The class destructor.
+    ~XmlNodeIterator() {
         // empty
     }
 
+    ///	@brief  Will iterate through all children in pre-order iteration.
+    /// @param  node    [in] The nod to iterate through.
     void collectChildrenPreOrder( XmlNode &node ) {
-        
         if (node != mParent && node.type() == pugi::node_element) {
             mNodes.push_back(node);
         }
@@ -287,6 +409,8 @@ public:
         }
     }
 
+    ///	@brief  Will iterate through all children in post-order iteration.
+    /// @param  node    [in] The nod to iterate through.
     void collectChildrenPostOrder(XmlNode &node) {
         for (XmlNode currentNode = node.first_child(); currentNode; currentNode = currentNode.next_sibling()) {
             collectChildrenPostOrder(currentNode);
@@ -296,6 +420,9 @@ public:
         }
     }
 
+    ///	@brief  Will iterate through all collected nodes.
+    /// @param  next    The next node, if there is any.
+    /// @return true, if there is a node left.
     bool getNext(XmlNode &next) {
         if (mIndex == mNodes.size()) {
             return false;
@@ -307,14 +434,19 @@ public:
         return true;
     }
 
+    ///	@brief  Will return the number of collected nodes.
+    /// @return The number of collected nodes.
     size_t size() const {
         return mNodes.size();
     }
 
+    ///	@brief  Returns true, if the node is empty.
+    /// @return true, if the node is empty, false if not.
     bool isEmpty() const {
         return mNodes.empty();
     }
 
+    ///	@brief  Will clear all collected nodes.
     void clear() {
         if (mNodes.empty()) {
             return;
diff --git a/include/assimp/fast_atof.h b/include/assimp/fast_atof.h
index 9ea49c85c..aea793f35 100644
--- a/include/assimp/fast_atof.h
+++ b/include/assimp/fast_atof.h
@@ -29,6 +29,7 @@
 #include "StringComparison.h"
 #include <assimp/DefaultLogger.hpp>
 #include <assimp/Exceptional.h>
+#include <assimp/StringUtils.h>
 
 #ifdef _MSC_VER
 #  include <stdint.h>
@@ -193,7 +194,7 @@ uint64_t strtoul10_64( const char* in, const char** out=0, unsigned int* max_ino
 
     if ( *in < '0' || *in > '9' ) {
         // The string is known to be bad, so don't risk printing the whole thing.
-        throw ExceptionType("The string \"", std::string(in).substr(0, 100), "\" cannot be converted into a value." );
+        throw ExceptionType("The string \"", ai_str_toprintable(in, 30), "\" cannot be converted into a value." );
     }
 
     for ( ;; ) {
@@ -205,7 +206,7 @@ uint64_t strtoul10_64( const char* in, const char** out=0, unsigned int* max_ino
 
         // numeric overflow, we rely on you
         if ( new_value < value ) {
-            ASSIMP_LOG_WARN_F( "Converting the string \"", in, "\" into a value resulted in overflow." );
+            ASSIMP_LOG_WARN( "Converting the string \"", in, "\" into a value resulted in overflow." );
             return 0;
         }
 
@@ -293,7 +294,7 @@ const char* fast_atoreal_move(const char* c, Real& out, bool check_comma = true)
     if (!(c[0] >= '0' && c[0] <= '9') &&
             !((c[0] == '.' || (check_comma && c[0] == ',')) && c[1] >= '0' && c[1] <= '9')) {
         // The string is known to be bad, so don't risk printing the whole thing.
-        throw ExceptionType("Cannot parse string \"", std::string(c).substr(0, 100), 
+        throw ExceptionType("Cannot parse string \"", ai_str_toprintable(c, 30),
                                     "\" as a real number: does not start with digit "
                                     "or decimal point followed by digit.");
     }
diff --git a/port/PyAssimp/pyassimp/helper.py b/port/PyAssimp/pyassimp/helper.py
index 5c1aca827..7a4b2bdcb 100644
--- a/port/PyAssimp/pyassimp/helper.py
+++ b/port/PyAssimp/pyassimp/helper.py
@@ -27,6 +27,7 @@ if os.name=='posix':
     additional_dirs.append('./')
     additional_dirs.append('/usr/lib/')
     additional_dirs.append('/usr/lib/x86_64-linux-gnu/')
+    additional_dirs.append('/usr/lib/aarch64-linux-gnu/')
     additional_dirs.append('/usr/local/lib/')
 
     if 'LD_LIBRARY_PATH' in os.environ:
diff --git a/port/PyAssimp/pyassimp/structs.py b/port/PyAssimp/pyassimp/structs.py
index 809afae54..e1fba1950 100644
--- a/port/PyAssimp/pyassimp/structs.py
+++ b/port/PyAssimp/pyassimp/structs.py
@@ -1,6 +1,6 @@
 #-*- coding: utf-8 -*-
 
-from ctypes import POINTER, c_void_p, c_uint, c_char, c_float, Structure, c_char_p, c_double, c_ubyte, c_size_t, c_uint32
+from ctypes import POINTER, c_void_p, c_uint, c_char, c_float, Structure, c_double, c_ubyte, c_size_t, c_uint32
 
 
 class Vector2D(Structure):
@@ -1121,7 +1121,7 @@ class Scene(Structure):
             ("mMetadata", POINTER(Metadata)),
 
             # Internal data, do not touch
-            ("mPrivate", c_char_p),
+            ("mPrivate", POINTER(c_char)),
         ]
 
 assimp_structs_as_tuple = (Matrix4x4,
diff --git a/samples/SimpleTexturedDirectx11/SimpleTexturedDirectx11/ModelLoader.cpp b/samples/SimpleTexturedDirectx11/SimpleTexturedDirectx11/ModelLoader.cpp
index 733d3d620..92760d691 100644
--- a/samples/SimpleTexturedDirectx11/SimpleTexturedDirectx11/ModelLoader.cpp
+++ b/samples/SimpleTexturedDirectx11/SimpleTexturedDirectx11/ModelLoader.cpp
@@ -42,22 +42,12 @@ void ModelLoader::Draw(ID3D11DeviceContext * devcon) {
 	}
 }
 
-std::string textype;
-
 Mesh ModelLoader::processMesh(aiMesh * mesh, const aiScene * scene) {
 	// Data to fill
 	std::vector<VERTEX> vertices;
 	std::vector<UINT> indices;
 	std::vector<Texture> textures;
 
-	if (mesh->mMaterialIndex >= 0) {
-		aiMaterial* mat = scene->mMaterials[mesh->mMaterialIndex];
-
-		if (textype.empty()) {
-            textype = determineTextureType(scene, mat);
-        }
-	}
-
 	// Walk through each of the mesh's vertices
 	for (UINT i = 0; i < mesh->mNumVertices; i++) {
 		VERTEX vertex;
@@ -108,9 +98,10 @@ std::vector<Texture> ModelLoader::loadMaterialTextures(aiMaterial * mat, aiTextu
 		if (!skip) {   // If texture hasn't been loaded already, load it
 			HRESULT hr;
 			Texture texture;
-			if (textype == "embedded compressed texture") {
-				int textureindex = getTextureIndex(&str);
-				texture.texture = getTextureFromModel(scene, textureindex);
+
+			const aiTexture* embeddedTexture = scene->GetEmbeddedTexture(str.C_Str());
+			if (embeddedTexture != nullptr) {
+				texture.texture = loadEmbeddedTexture(embeddedTexture);
 			} else {
 				std::string filename = std::string(str.C_Str());
 				filename = directory_ + '/' + filename;
@@ -148,38 +139,46 @@ void ModelLoader::processNode(aiNode * node, const aiScene * scene) {
 	}
 }
 
-std::string ModelLoader::determineTextureType(const aiScene * scene, aiMaterial * mat) {
-	aiString textypeStr;
-	mat->GetTexture(aiTextureType_DIFFUSE, 0, &textypeStr);
-	std::string textypeteststr = textypeStr.C_Str();
-	if (textypeteststr == "*0" || textypeteststr == "*1" || textypeteststr == "*2" || textypeteststr == "*3" || textypeteststr == "*4" || textypeteststr == "*5") {
-		if (scene->mTextures[0]->mHeight == 0) {
-			return "embedded compressed texture";
-		} else {
-			return "embedded non-compressed texture";
-		}
-	}
-	if (textypeteststr.find('.') != std::string::npos) {
-		return "textures are on disk";
-	}
-
-    return ".";
-}
-
-int ModelLoader::getTextureIndex(aiString * str) {
-	std::string tistr;
-	tistr = str->C_Str();
-	tistr = tistr.substr(1);
-	return stoi(tistr);
-}
-
-ID3D11ShaderResourceView * ModelLoader::getTextureFromModel(const aiScene * scene, int textureindex) {
+ID3D11ShaderResourceView * ModelLoader::loadEmbeddedTexture(const aiTexture* embeddedTexture) {
 	HRESULT hr;
-	ID3D11ShaderResourceView *texture;
+	ID3D11ShaderResourceView *texture = nullptr;
 
-	int* size = reinterpret_cast<int*>(&scene->mTextures[textureindex]->mWidth);
+	if (embeddedTexture->mHeight != 0) {
+		// Load an uncompressed ARGB8888 embedded texture
+		D3D11_TEXTURE2D_DESC desc;
+		desc.Width = embeddedTexture->mWidth;
+		desc.Height = embeddedTexture->mHeight;
+		desc.MipLevels = 1;
+		desc.ArraySize = 1;
+		desc.SampleDesc.Count = 1;
+		desc.SampleDesc.Quality = 0;
+		desc.Usage = D3D11_USAGE_DEFAULT;
+		desc.Format = DXGI_FORMAT_B8G8R8A8_UNORM;
+		desc.BindFlags = D3D11_BIND_SHADER_RESOURCE;
+		desc.CPUAccessFlags = 0;
+		desc.MiscFlags = 0;
 
-	hr = CreateWICTextureFromMemory(dev_, devcon_, reinterpret_cast<unsigned char*>(scene->mTextures[textureindex]->pcData), *size, nullptr, &texture);
+		D3D11_SUBRESOURCE_DATA subresourceData;
+		subresourceData.pSysMem = embeddedTexture->pcData;
+		subresourceData.SysMemPitch = embeddedTexture->mWidth * 4;
+		subresourceData.SysMemSlicePitch = embeddedTexture->mWidth * embeddedTexture->mHeight * 4;
+
+		ID3D11Texture2D *texture2D = nullptr;
+		hr = dev_->CreateTexture2D(&desc, &subresourceData, &texture2D);
+		if (FAILED(hr))
+			MessageBox(hwnd_, "CreateTexture2D failed!", "Error!", MB_ICONERROR | MB_OK);
+
+		hr = dev_->CreateShaderResourceView(texture2D, nullptr, &texture);
+		if (FAILED(hr))
+			MessageBox(hwnd_, "CreateShaderResourceView failed!", "Error!", MB_ICONERROR | MB_OK);
+
+		return texture;
+	}
+
+	// mHeight is 0, so try to load a compressed texture of mWidth bytes
+	const size_t size = embeddedTexture->mWidth;
+
+	hr = CreateWICTextureFromMemory(dev_, devcon_, reinterpret_cast<const unsigned char*>(embeddedTexture->pcData), size, nullptr, &texture);
 	if (FAILED(hr))
 		MessageBox(hwnd_, "Texture couldn't be created from memory!", "Error!", MB_ICONERROR | MB_OK);
 
diff --git a/samples/SimpleTexturedDirectx11/SimpleTexturedDirectx11/ModelLoader.h b/samples/SimpleTexturedDirectx11/SimpleTexturedDirectx11/ModelLoader.h
index 9d3ed50b3..a04484f08 100644
--- a/samples/SimpleTexturedDirectx11/SimpleTexturedDirectx11/ModelLoader.h
+++ b/samples/SimpleTexturedDirectx11/SimpleTexturedDirectx11/ModelLoader.h
@@ -35,9 +35,7 @@ private:
 	void processNode(aiNode* node, const aiScene* scene);
 	Mesh processMesh(aiMesh* mesh, const aiScene* scene);
 	std::vector<Texture> loadMaterialTextures(aiMaterial* mat, aiTextureType type, std::string typeName, const aiScene* scene);
-	std::string determineTextureType(const aiScene* scene, aiMaterial* mat);
-	int getTextureIndex(aiString* str);
-	ID3D11ShaderResourceView* getTextureFromModel(const aiScene* scene, int textureindex);
+	ID3D11ShaderResourceView* loadEmbeddedTexture(const aiTexture* embeddedTexture);
 };
 
 #endif // !MODEL_LOADER_H
diff --git a/test/test.3mf b/test/test.3mf
new file mode 100644
index 000000000..eb1c49e1b
Binary files /dev/null and b/test/test.3mf differ
diff --git a/test/unit/Common/utXmlParser.cpp b/test/unit/Common/utXmlParser.cpp
index c27669dd1..7e992f9df 100644
--- a/test/unit/Common/utXmlParser.cpp
+++ b/test/unit/Common/utXmlParser.cpp
@@ -73,9 +73,7 @@ TEST_F(utXmlParser, parse_xml_and_traverse_test) {
     EXPECT_TRUE(result);
     XmlNode root = parser.getRootNode();
 
-    XmlNodeIterator nodeIt(root);
-    EXPECT_TRUE(nodeIt.isEmpty());
-    nodeIt.collectChildrenPreOrder(root);
+    XmlNodeIterator nodeIt(root, XmlNodeIterator::PreOrderMode);
     const size_t numNodes = nodeIt.size();
     bool empty = nodeIt.isEmpty();
     EXPECT_FALSE(empty);
diff --git a/test/unit/utImporter.cpp b/test/unit/utImporter.cpp
index 65b7f99ee..9d3b971a3 100644
--- a/test/unit/utImporter.cpp
+++ b/test/unit/utImporter.cpp
@@ -280,104 +280,84 @@ TEST_F(ImporterTest, SearchFileHeaderForTokenTest) {
     //    BaseImporter::SearchFileHeaderForToken( &ioSystem, assetPath, Token, 2 )
 }
 
+namespace {
+// Description for an importer which fails in specific ways.
+aiImporterDesc s_failingImporterDescription = {
+    "Failing importer",
+    "assimp team",
+    "",
+    "",
+    0,
+    1,
+    0,
+    1,
+    0,
+    "fail"
+};
 
-namespace
-{
-    // Description for an importer which fails in specific ways.
-    aiImporterDesc s_failingImporterDescription = {
-        "Failing importer",
-        "assimp team",
-        "",
-        "",
-        0,
-        1,
-        0,
-        1,
-        0,
-        "fail"
-    };
+// This importer fails in specific ways.
+class FailingImporter : public Assimp::BaseImporter {
+public:
+    virtual ~FailingImporter() = default;
+    virtual bool CanRead(const std::string &, Assimp::IOSystem *, bool) const override {
+        return true;
+    }
 
-    // This importer fails in specific ways.
-    class FailingImporter : public Assimp::BaseImporter {
-    public:
-        virtual ~FailingImporter() = default;
-        virtual bool CanRead( const std::string&, Assimp::IOSystem*, bool ) const override
-        {
-            return true;
+protected:
+    const aiImporterDesc *GetInfo() const override {
+        return &s_failingImporterDescription;
+    }
+
+    void InternReadFile(const std::string &pFile, aiScene *, Assimp::IOSystem *) override {
+        if (pFile == "deadlyImportError.fail") {
+            throw DeadlyImportError("Deadly import error test. Details: ", 42, " More Details: ", "Failure");
+        } else if (pFile == "stdException.fail") {
+            throw std::runtime_error("std::exception test");
+        } else if (pFile == "unexpectedException.fail") {
+            throw 5;
         }
+    }
+};
+} // namespace
 
-    protected:
-        virtual const aiImporterDesc* GetInfo() const override { return &s_failingImporterDescription; }
-
-        virtual void InternReadFile( const std::string& pFile, aiScene*, Assimp::IOSystem* ) override
-        {
-            if (pFile == "deadlyImportError.fail")
-            {
-                throw DeadlyImportError("Deadly import error test. Details: ", 42, " More Details: ", "Failure");
-            }
-            else if (pFile == "stdException.fail")
-            {
-                throw std::runtime_error("std::exception test");
-            }
-            else if (pFile == "unexpectedException.fail")
-            {
-                throw 5;
-            }
-        }
-    };
-}
-
-TEST_F(ImporterTest, deadlyImportError)
-{
+TEST_F(ImporterTest, deadlyImportError) {
     pImp->RegisterLoader(new FailingImporter);
     pImp->SetIOHandler(new TestIOSystem);
-    const aiScene* scene = pImp->ReadFile("deadlyImportError.fail", 0);
+    const aiScene *scene = pImp->ReadFile("deadlyImportError.fail", 0);
     EXPECT_EQ(scene, nullptr);
     EXPECT_STREQ(pImp->GetErrorString(), "Deadly import error test. Details: 42 More Details: Failure");
     EXPECT_NE(pImp->GetException(), std::exception_ptr());
 }
 
-TEST_F(ImporterTest, stdException)
-{
+TEST_F(ImporterTest, stdException) {
     pImp->RegisterLoader(new FailingImporter);
     pImp->SetIOHandler(new TestIOSystem);
-    const aiScene* scene = pImp->ReadFile("stdException.fail", 0);
+    const aiScene *scene = pImp->ReadFile("stdException.fail", 0);
     EXPECT_EQ(scene, nullptr);
     EXPECT_STREQ(pImp->GetErrorString(), "std::exception test");
     EXPECT_NE(pImp->GetException(), std::exception_ptr());
-    try
-    {
+    try {
         std::rethrow_exception(pImp->GetException());
-    }
-    catch(const std::exception& e)
-    {
+    } catch (const std::exception &e) {
         EXPECT_STREQ(e.what(), "std::exception test");
-    }
-    catch(...)
-    {
+    } catch (...) {
         EXPECT_TRUE(false);
     }
 }
 
-TEST_F(ImporterTest, unexpectedException)
-{
+TEST_F(ImporterTest, unexpectedException) {
     pImp->RegisterLoader(new FailingImporter);
     pImp->SetIOHandler(new TestIOSystem);
-    const aiScene* scene = pImp->ReadFile("unexpectedException.fail", 0);
+    const aiScene *scene = pImp->ReadFile("unexpectedException.fail", 0);
 
     EXPECT_EQ(scene, nullptr);
     EXPECT_STREQ(pImp->GetErrorString(), "Unknown exception");
     ASSERT_NE(pImp->GetException(), std::exception_ptr());
-    try
-    {
+    try {
         std::rethrow_exception(pImp->GetException());
-    }
-    catch(int x)
-    {
+    } catch (int x) {
         EXPECT_EQ(x, 5);
-    }
-    catch(...)
-    {
+    } catch (...) {
         EXPECT_TRUE(false);
     }
 }
diff --git a/test/unit/utStringUtils.cpp b/test/unit/utStringUtils.cpp
index 6a10cba24..08be82e9a 100644
--- a/test/unit/utStringUtils.cpp
+++ b/test/unit/utStringUtils.cpp
@@ -42,9 +42,10 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/StringUtils.h>
 
 class utStringUtils : public ::testing::Test {
+    // empty
 };
 
-TEST_F( utStringUtils, to_string_Test ) {
+TEST_F(utStringUtils, to_string_Test ) {
     std::string res = ai_to_string( 1 );
     EXPECT_EQ( res, "1" );
 
@@ -52,7 +53,7 @@ TEST_F( utStringUtils, to_string_Test ) {
     EXPECT_EQ( res, "1" );
 }
 
-TEST_F( utStringUtils, ai_strtofTest ) {
+TEST_F(utStringUtils, ai_strtofTest ) {
     float res = ai_strtof( nullptr, nullptr );
     EXPECT_FLOAT_EQ( res, 0.0f );
 
@@ -66,3 +67,11 @@ TEST_F( utStringUtils, ai_strtofTest ) {
     res = ai_strtof( begin, end );
     EXPECT_FLOAT_EQ( res, 200.0f );
 }
+
+TEST_F(utStringUtils, ai_rgba2hexTest) {
+    std::string result;
+    result = ai_rgba2hex(255, 255, 255, 255, true);
+    EXPECT_EQ(result, "#ffffffff");
+    result = ai_rgba2hex(0, 0, 0, 0, false);
+    EXPECT_EQ(result, "00000000");
+}
diff --git a/tools/assimp_cmd/ImageExtractor.cpp b/tools/assimp_cmd/ImageExtractor.cpp
index 58aa42fa8..105c4fe37 100644
--- a/tools/assimp_cmd/ImageExtractor.cpp
+++ b/tools/assimp_cmd/ImageExtractor.cpp
@@ -130,8 +130,9 @@ int SaveAsBMP(FILE *file, const aiTexel *data, unsigned int width, unsigned int
             s[0] = t->b;
             s[1] = t->g;
             s[2] = t->r;
-            if (4 == numc)
+            if (4 == numc) {
                 s[3] = t->a;
+            }
         }
     }
 
@@ -296,7 +297,7 @@ int Assimp_Extract(const char *const *params, unsigned int num) {
 
         // check whether the requested texture is existing
         if (texIdx >= scene->mNumTextures) {
-            ::printf("assimp extract: Texture %i requested, but there are just %i textures\n",
+            ::printf("assimp extract: Texture %u requested, but there are just %i textures\n",
                     texIdx, scene->mNumTextures);
             return AssimpCmdExtractError::TextureIndexIsOutOfRange;
         }
@@ -325,7 +326,7 @@ int Assimp_Extract(const char *const *params, unsigned int num) {
         // if the texture is a compressed one, we'll export
         // it to its native file format
         if (!tex->mHeight) {
-            printf("assimp extract: Texture %i is compressed (%s). Writing native file format.\n",
+            printf("assimp extract: Texture %u is compressed (%s). Writing native file format.\n",
                     i, tex->achFormatHint);
 
             // modify file extension
@@ -350,7 +351,7 @@ int Assimp_Extract(const char *const *params, unsigned int num) {
         }
         ::fclose(p);
 
-        printf("assimp extract: Wrote texture %i to %s\n", i, out_cpy.c_str());
+        printf("assimp extract: Wrote texture %u to %s\n", i, out_cpy.c_str());
         if (texIdx != 0xffffffff) {
             return m;
         }
diff --git a/tools/assimp_view/Material.cpp b/tools/assimp_view/Material.cpp
index 8141fb58c..bcc93011e 100644
--- a/tools/assimp_view/Material.cpp
+++ b/tools/assimp_view/Material.cpp
@@ -272,7 +272,7 @@ bool CMaterialManager::TryLongerPath(char* szTemp,aiString* p_szString)
                             szExtFound - 1 - info.cFileName);
 
                         for (unsigned int i = 0; i < iSizeFound;++i)
-                            info.cFileName[i] = (CHAR)tolower(info.cFileName[i]);
+                            info.cFileName[i] = (CHAR)tolower((unsigned char)info.cFileName[i]);
 
                         if (0 == memcmp(info.cFileName,szFile2, std::min(iSizeFound,iSize)))
                         {
@@ -354,7 +354,7 @@ int CMaterialManager::FindValidPath(aiString* p_szString)
             for (unsigned int i = 0;;++i)
             {
                 if ('\0' == szTemp[i])break;
-                szTemp[i] = (char)tolower(szTemp[i]);
+                szTemp[i] = (char)tolower((unsigned char)szTemp[i]);
             }
 
             if(TryLongerPath(szTemp,p_szString))return 1;