diff --git a/code/AssetLib/B3D/B3DImporter.cpp b/code/AssetLib/B3D/B3DImporter.cpp
index e87744603..bf8145798 100644
--- a/code/AssetLib/B3D/B3DImporter.cpp
+++ b/code/AssetLib/B3D/B3DImporter.cpp
@@ -418,7 +418,6 @@ void B3DImporter::ReadTRIS(int v0) {
             ASSIMP_LOG_ERROR("Bad triangle index: i0=", i0, ", i1=", i1, ", i2=", i2);
 #endif
             Fail("Bad triangle index");
-            continue;
         }
         face->mNumIndices = 3;
         face->mIndices = new unsigned[3];
diff --git a/code/AssetLib/FBX/FBXConverter.cpp b/code/AssetLib/FBX/FBXConverter.cpp
index 257845384..d742af447 100644
--- a/code/AssetLib/FBX/FBXConverter.cpp
+++ b/code/AssetLib/FBX/FBXConverter.cpp
@@ -152,7 +152,7 @@ void FBXConverter::ConvertRootNode() {
     mSceneOut->mRootNode->mName.Set(unique_name);
 
     // root has ID 0
-    ConvertNodes(0L, mSceneOut->mRootNode, mSceneOut->mRootNode);
+    ConvertNodes(0L, mSceneOut->mRootNode, mSceneOut->mRootNode, aiMatrix4x4());
 }
 
 static std::string getAncestorBaseName(const aiNode *node) {
@@ -196,7 +196,7 @@ struct FBXConverter::PotentialNode {
 /// todo: get bone from stack
 /// todo: make map of aiBone* to aiNode*
 /// then update convert clusters to the new format
-void FBXConverter::ConvertNodes(uint64_t id, aiNode *parent, aiNode *root_node) {
+void FBXConverter::ConvertNodes(uint64_t id, aiNode *parent, aiNode *root_node, const aiMatrix4x4 &globalTransform) {
     const std::vector<const Connection *> &conns = doc.GetConnectionsByDestinationSequenced(id, "Model");
 
     std::vector<PotentialNode> nodes;
@@ -290,14 +290,15 @@ void FBXConverter::ConvertNodes(uint64_t id, aiNode *parent, aiNode *root_node)
             }
 
             // recursion call - child nodes
-            ConvertNodes(model->ID(), last_parent, root_node);
+            aiMatrix4x4 newGlobalMatrix = globalTransform * nodes_chain.front().mNode->mTransformation;
+            ConvertNodes(model->ID(), last_parent, root_node, newGlobalMatrix);
 
             if (doc.Settings().readLights) {
                 ConvertLights(*model, node_name);
             }
 
             if (doc.Settings().readCameras) {
-                ConvertCameras(*model, node_name);
+                ConvertCameras(*model, node_name, newGlobalMatrix);
             }
 
             nodes.push_back(std::move(nodes_chain.front()));
@@ -327,12 +328,14 @@ void FBXConverter::ConvertLights(const Model &model, const std::string &orig_nam
     }
 }
 
-void FBXConverter::ConvertCameras(const Model &model, const std::string &orig_name) {
+void FBXConverter::ConvertCameras(const Model &model,
+                                  const std::string &orig_name,
+                                  const aiMatrix4x4 &transform) {
     const std::vector<const NodeAttribute *> &node_attrs = model.GetAttributes();
     for (const NodeAttribute *attr : node_attrs) {
         const Camera *const cam = dynamic_cast<const Camera *>(attr);
         if (cam) {
-            ConvertCamera(*cam, orig_name);
+            ConvertCamera(*cam, orig_name, transform);
         }
     }
 }
@@ -413,7 +416,9 @@ void FBXConverter::ConvertLight(const Light &light, const std::string &orig_name
     }
 }
 
-void FBXConverter::ConvertCamera(const Camera &cam, const std::string &orig_name) {
+void FBXConverter::ConvertCamera(const Camera &cam,
+                                 const std::string &orig_name,
+                                 aiMatrix4x4 transform) {
     cameras.push_back(new aiCamera());
     aiCamera *const out_camera = cameras.back();
 
@@ -421,9 +426,16 @@ void FBXConverter::ConvertCamera(const Camera &cam, const std::string &orig_name
 
     out_camera->mAspect = cam.AspectWidth() / cam.AspectHeight();
 
+    aiVector3D pos = cam.Position();
+    out_camera->mLookAt = cam.InterestPosition();
+    out_camera->mUp = pos + cam.UpVector();
+    transform.Inverse();
+    pos *= transform;
+    out_camera->mLookAt *= transform;
+    out_camera->mUp *= transform;
+    out_camera->mLookAt -= pos;
+    out_camera->mUp -= pos;
     out_camera->mPosition = aiVector3D(0.0f);
-    out_camera->mLookAt = aiVector3D(1.0f, 0.0f, 0.0f);
-    out_camera->mUp = aiVector3D(0.0f, 1.0f, 0.0f);
 
     out_camera->mHorizontalFOV = AI_DEG_TO_RAD(cam.FieldOfView());
 
diff --git a/code/AssetLib/FBX/FBXConverter.h b/code/AssetLib/FBX/FBXConverter.h
index 41acb6ffe..b9b6c46b0 100644
--- a/code/AssetLib/FBX/FBXConverter.h
+++ b/code/AssetLib/FBX/FBXConverter.h
@@ -134,19 +134,22 @@ private:
 
     // ------------------------------------------------------------------------------------------------
     // collect and assign child nodes
-    void ConvertNodes(uint64_t id, aiNode *parent, aiNode *root_node);
+    void ConvertNodes(uint64_t id, aiNode *parent, aiNode *root_node,
+                      const aiMatrix4x4 &globalTransform);
 
     // ------------------------------------------------------------------------------------------------
     void ConvertLights(const Model& model, const std::string &orig_name );
 
     // ------------------------------------------------------------------------------------------------
-    void ConvertCameras(const Model& model, const std::string &orig_name );
+    void ConvertCameras(const Model& model, const std::string &orig_name,
+                        const aiMatrix4x4 &transform);
 
     // ------------------------------------------------------------------------------------------------
     void ConvertLight( const Light& light, const std::string &orig_name );
 
     // ------------------------------------------------------------------------------------------------
-    void ConvertCamera( const Camera& cam, const std::string &orig_name );
+    void ConvertCamera(const Camera& cam, const std::string &orig_name,
+                       aiMatrix4x4 transform);
 
     // ------------------------------------------------------------------------------------------------
     void GetUniqueName( const std::string &name, std::string& uniqueName );
diff --git a/code/AssetLib/LWO/LWOMaterial.cpp b/code/AssetLib/LWO/LWOMaterial.cpp
index 50bac884b..8d83dfb67 100644
--- a/code/AssetLib/LWO/LWOMaterial.cpp
+++ b/code/AssetLib/LWO/LWOMaterial.cpp
@@ -345,7 +345,7 @@ void LWOImporter::ConvertMaterial(const LWO::Surface &surf, aiMaterial *pcMat) {
 
     // (the diffuse value is just a scaling factor)
     // If a diffuse texture is set, we set this value to 1.0
-    clr = (b && false ? aiColor3D(1.0, 1.0, 1.0) : surf.mColor);
+    clr = (b ? aiColor3D(1.0, 1.0, 1.0) : surf.mColor);
     clr.r *= surf.mDiffuseValue;
     clr.g *= surf.mDiffuseValue;
     clr.b *= surf.mDiffuseValue;
diff --git a/code/AssetLib/glTF2/glTF2Asset.h b/code/AssetLib/glTF2/glTF2Asset.h
index 1d7cff325..cf9c8f11c 100644
--- a/code/AssetLib/glTF2/glTF2Asset.h
+++ b/code/AssetLib/glTF2/glTF2Asset.h
@@ -565,7 +565,7 @@ struct Accessor : public Object {
     inline size_t GetMaxByteSize();
 
     template <class T>
-    void ExtractData(T *&outData);
+    size_t ExtractData(T *&outData, const std::vector<unsigned int> *remappingIndices = nullptr);
 
     void WriteData(size_t count, const void *src_buffer, size_t src_stride);
     void WriteSparseValues(size_t count, const void *src_data, size_t src_dataStride);
diff --git a/code/AssetLib/glTF2/glTF2Asset.inl b/code/AssetLib/glTF2/glTF2Asset.inl
index 0e2998357..b4ea77c79 100644
--- a/code/AssetLib/glTF2/glTF2Asset.inl
+++ b/code/AssetLib/glTF2/glTF2Asset.inl
@@ -962,14 +962,15 @@ inline size_t Accessor::GetMaxByteSize() {
 }
 
 template <class T>
-void Accessor::ExtractData(T *&outData) {
+size_t Accessor::ExtractData(T *&outData, const std::vector<unsigned int> *remappingIndices) {
     uint8_t *data = GetPointer();
     if (!data) {
         throw DeadlyImportError("GLTF2: data is null when extracting data from ", getContextForErrorMessages(id, name));
     }
 
+    const size_t usedCount = (remappingIndices != nullptr) ? remappingIndices->size() : count;
     const size_t elemSize = GetElementSize();
-    const size_t totalSize = elemSize * count;
+    const size_t totalSize = elemSize * usedCount;
 
     const size_t stride = GetStride();
 
@@ -980,18 +981,31 @@ void Accessor::ExtractData(T *&outData) {
     }
 
     const size_t maxSize = GetMaxByteSize();
-    if (count * stride > maxSize) {
-        throw DeadlyImportError("GLTF: count*stride ", (count * stride), " > maxSize ", maxSize, " in ", getContextForErrorMessages(id, name));
-    }
 
-    outData = new T[count];
-    if (stride == elemSize && targetElemSize == elemSize) {
-        memcpy(outData, data, totalSize);
-    } else {
-        for (size_t i = 0; i < count; ++i) {
-            memcpy(outData + i, data + i * stride, elemSize);
+    outData = new T[usedCount];
+
+    if (remappingIndices != nullptr) {
+        const unsigned int maxIndex = static_cast<unsigned int>(maxSize / stride - 1);
+        for (size_t i = 0; i < usedCount; ++i) {
+            size_t srcIdx = (*remappingIndices)[i];
+            if (srcIdx > maxIndex) {
+                throw DeadlyImportError("GLTF: index*stride ", (srcIdx * stride), " > maxSize ", maxSize, " in ", getContextForErrorMessages(id, name));
+            }
+            memcpy(outData + i, data + srcIdx * stride, elemSize);
+        }
+    } else { // non-indexed cases
+        if (usedCount * stride > maxSize) {
+            throw DeadlyImportError("GLTF: count*stride ", (usedCount * stride), " > maxSize ", maxSize, " in ", getContextForErrorMessages(id, name));
+        }
+        if (stride == elemSize && targetElemSize == elemSize) {
+            memcpy(outData, data, totalSize);
+        } else {
+            for (size_t i = 0; i < usedCount; ++i) {
+                memcpy(outData + i, data + i * stride, elemSize);
+            }
         }
     }
+    return usedCount;
 }
 
 inline void Accessor::WriteData(size_t _count, const void *src_buffer, size_t src_stride) {
diff --git a/code/AssetLib/glTF2/glTF2Importer.cpp b/code/AssetLib/glTF2/glTF2Importer.cpp
index fda89c2a7..394264a12 100644
--- a/code/AssetLib/glTF2/glTF2Importer.cpp
+++ b/code/AssetLib/glTF2/glTF2Importer.cpp
@@ -453,6 +453,11 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
     unsigned int k = 0;
     meshOffsets.clear();
 
+
+    std::vector<unsigned int> usedVertexIndices;
+    std::vector<unsigned int> reverseMappingIndices;
+    std::vector<unsigned int> indexBuffer;
+
     for (unsigned int m = 0; m < r.meshes.Size(); ++m) {
         Mesh &mesh = r.meshes[m];
 
@@ -462,6 +467,50 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
         for (unsigned int p = 0; p < mesh.primitives.size(); ++p) {
             Mesh::Primitive &prim = mesh.primitives[p];
 
+            Mesh::Primitive::Attributes &attr = prim.attributes;
+
+            // Find out the maximum number of vertices:
+            size_t numAllVertices = 0;
+            if (!attr.position.empty() && attr.position[0]) {
+                numAllVertices = attr.position[0]->count;
+            }
+
+            // Extract used vertices:
+            bool useIndexBuffer = prim.indices;
+            std::vector<unsigned int>* vertexRemappingTable = nullptr;
+            if (useIndexBuffer) {
+                size_t count = prim.indices->count;
+                indexBuffer.resize(count);
+                usedVertexIndices.clear();
+                reverseMappingIndices.clear();
+                usedVertexIndices.reserve(count / 3); // this is a very rough heuristic to reduce re-allocations
+                vertexRemappingTable = &usedVertexIndices;
+                Accessor::Indexer data = prim.indices->GetIndexer();
+                if (!data.IsValid()) {
+                    throw DeadlyImportError("GLTF: Invalid accessor without data in mesh ", getContextForErrorMessages(mesh.id, mesh.name));
+                }
+
+                // Build the vertex remapping table and the modified index buffer (used later instead of the original one)
+                // In case no index buffer is used, the original vertex arrays are being used so no remapping is required in the first place.
+                const unsigned int unusedIndex = ~0u;
+                for (unsigned int i = 0; i < count; ++i) {
+                    unsigned int index = data.GetUInt(i);
+                    if (index >= numAllVertices) {
+                        // Out-of-range indices will be filtered out when adding the faces and then lead to a warning. At this stage, we just keep them.
+                        indexBuffer[i] = index;
+                        continue; 
+                    }
+                    if (index >= reverseMappingIndices.size()) {
+                        reverseMappingIndices.resize(index + 1, unusedIndex);
+                    }
+                    if (reverseMappingIndices[index] == unusedIndex) {
+                        reverseMappingIndices[index] = static_cast<unsigned int>(usedVertexIndices.size());
+                        usedVertexIndices.push_back(index);
+                    }
+                    indexBuffer[i] = reverseMappingIndices[index];
+                }
+            }
+
             aiMesh *aim = new aiMesh();
             meshes.push_back(std::unique_ptr<aiMesh>(aim));
 
@@ -491,28 +540,25 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                 break;
             }
 
-            Mesh::Primitive::Attributes &attr = prim.attributes;
-
             if (!attr.position.empty() && attr.position[0]) {
-                aim->mNumVertices = static_cast<unsigned int>(attr.position[0]->count);
-                attr.position[0]->ExtractData(aim->mVertices);
+                aim->mNumVertices = static_cast<unsigned int>(attr.position[0]->ExtractData(aim->mVertices, vertexRemappingTable));
             }
 
             if (!attr.normal.empty() && attr.normal[0]) {
-                if (attr.normal[0]->count != aim->mNumVertices) {
+                    if (attr.normal[0]->count != numAllVertices) {
                     DefaultLogger::get()->warn("Normal count in mesh \"", mesh.name, "\" does not match the vertex count, normals ignored.");
                 } else {
-                    attr.normal[0]->ExtractData(aim->mNormals);
+                    attr.normal[0]->ExtractData(aim->mNormals, vertexRemappingTable);
 
                     // only extract tangents if normals are present
                     if (!attr.tangent.empty() && attr.tangent[0]) {
-                        if (attr.tangent[0]->count != aim->mNumVertices) {
+                        if (attr.tangent[0]->count != numAllVertices) {
                             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;
 
-                            attr.tangent[0]->ExtractData(tangents);
+                            attr.tangent[0]->ExtractData(tangents, vertexRemappingTable);
 
                             aim->mTangents = new aiVector3D[aim->mNumVertices];
                             aim->mBitangents = new aiVector3D[aim->mNumVertices];
@@ -529,7 +575,7 @@ 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) {
+                if (attr.color[c]->count != numAllVertices) {
                     DefaultLogger::get()->warn("Color stream size in mesh \"", mesh.name,
                             "\" does not match the vertex count");
                     continue;
@@ -537,7 +583,7 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
 
                 auto componentType = attr.color[c]->componentType;
                 if (componentType == glTF2::ComponentType_FLOAT) {
-                    attr.color[c]->ExtractData(aim->mColors[c]);
+                    attr.color[c]->ExtractData(aim->mColors[c], vertexRemappingTable);
                 } else {
                     if (componentType == glTF2::ComponentType_UNSIGNED_BYTE) {
                         aim->mColors[c] = GetVertexColorsForType<unsigned char>(attr.color[c]);
@@ -552,13 +598,13 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                     continue;
                 }
 
-                if (attr.texcoord[tc]->count != aim->mNumVertices) {
+                if (attr.texcoord[tc]->count != numAllVertices) {
                     DefaultLogger::get()->warn("Texcoord stream size in mesh \"", mesh.name,
                             "\" does not match the vertex count");
                     continue;
                 }
 
-                attr.texcoord[tc]->ExtractData(aim->mTextureCoords[tc]);
+                attr.texcoord[tc]->ExtractData(aim->mTextureCoords[tc], vertexRemappingTable);
                 aim->mNumUVComponents[tc] = attr.texcoord[tc]->GetNumComponents();
 
                 aiVector3D *values = aim->mTextureCoords[tc];
@@ -583,11 +629,11 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                     Mesh::Primitive::Target &target = targets[i];
 
                     if (needPositions) {
-                        if (target.position[0]->count != aim->mNumVertices) {
+                        if (target.position[0]->count != numAllVertices) {
                             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);
+                            target.position[0]->ExtractData(positionDiff, vertexRemappingTable);
                             for (unsigned int vertexId = 0; vertexId < aim->mNumVertices; vertexId++) {
                                 aiAnimMesh.mVertices[vertexId] += positionDiff[vertexId];
                             }
@@ -595,11 +641,11 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                         }
                     }
                     if (needNormals) {
-                        if (target.normal[0]->count != aim->mNumVertices) {
+                        if (target.normal[0]->count != numAllVertices) {
                             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);
+                            target.normal[0]->ExtractData(normalDiff, vertexRemappingTable);
                             for (unsigned int vertexId = 0; vertexId < aim->mNumVertices; vertexId++) {
                                 aiAnimMesh.mNormals[vertexId] += normalDiff[vertexId];
                             }
@@ -610,14 +656,14 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                         if (!aiAnimMesh.HasNormals()) {
                             // prevent nullptr access to aiAnimMesh.mNormals below when no normals are available
                             ASSIMP_LOG_WARN("Bitangents of target ", i, " in mesh \"", mesh.name, "\" can't be computed, because mesh has no normals.");
-                        } else if (target.tangent[0]->count != aim->mNumVertices) {
+                        } else if (target.tangent[0]->count != numAllVertices) {
                             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);
+                            attr.tangent[0]->ExtractData(tangent, vertexRemappingTable);
 
                             aiVector3D *tangentDiff = nullptr;
-                            target.tangent[0]->ExtractData(tangentDiff);
+                            target.tangent[0]->ExtractData(tangentDiff, vertexRemappingTable);
 
                             for (unsigned int vertexId = 0; vertexId < aim->mNumVertices; ++vertexId) {
                                 tangent[vertexId].xyz += tangentDiff[vertexId];
@@ -641,20 +687,15 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
             aiFace *facePtr = nullptr;
             size_t nFaces = 0;
 
-            if (prim.indices) {
-                size_t count = prim.indices->count;
-
-                Accessor::Indexer data = prim.indices->GetIndexer();
-                if (!data.IsValid()) {
-                    throw DeadlyImportError("GLTF: Invalid accessor without data in mesh ", getContextForErrorMessages(mesh.id, mesh.name));
-                }
+            if (useIndexBuffer) {
+                size_t count = indexBuffer.size();
 
                 switch (prim.mode) {
                 case PrimitiveMode_POINTS: {
                     nFaces = count;
                     facePtr = faces = new aiFace[nFaces];
                     for (unsigned int i = 0; i < count; ++i) {
-                        SetFaceAndAdvance1(facePtr, aim->mNumVertices, data.GetUInt(i));
+                        SetFaceAndAdvance1(facePtr, aim->mNumVertices, indexBuffer[i]);
                     }
                     break;
                 }
@@ -667,7 +708,7 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                     }
                     facePtr = faces = new aiFace[nFaces];
                     for (unsigned int i = 0; i < count; i += 2) {
-                        SetFaceAndAdvance2(facePtr, aim->mNumVertices, data.GetUInt(i), data.GetUInt(i + 1));
+                        SetFaceAndAdvance2(facePtr, aim->mNumVertices, indexBuffer[i], indexBuffer[i + 1]);
                     }
                     break;
                 }
@@ -676,12 +717,12 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                 case PrimitiveMode_LINE_STRIP: {
                     nFaces = count - ((prim.mode == PrimitiveMode_LINE_STRIP) ? 1 : 0);
                     facePtr = faces = new aiFace[nFaces];
-                    SetFaceAndAdvance2(facePtr, aim->mNumVertices, data.GetUInt(0), data.GetUInt(1));
+                    SetFaceAndAdvance2(facePtr, aim->mNumVertices, indexBuffer[0], indexBuffer[1]);
                     for (unsigned int i = 2; i < count; ++i) {
-                        SetFaceAndAdvance2(facePtr, aim->mNumVertices, data.GetUInt(i - 1), data.GetUInt(i));
+                        SetFaceAndAdvance2(facePtr, aim->mNumVertices, indexBuffer[i - 1], indexBuffer[i]);
                     }
                     if (prim.mode == PrimitiveMode_LINE_LOOP) { // close the loop
-                        SetFaceAndAdvance2(facePtr, aim->mNumVertices, data.GetUInt(static_cast<int>(count) - 1), faces[0].mIndices[0]);
+                        SetFaceAndAdvance2(facePtr, aim->mNumVertices, indexBuffer[static_cast<int>(count) - 1], faces[0].mIndices[0]);
                     }
                     break;
                 }
@@ -694,7 +735,7 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                     }
                     facePtr = faces = new aiFace[nFaces];
                     for (unsigned int i = 0; i < count; i += 3) {
-                        SetFaceAndAdvance3(facePtr, aim->mNumVertices, data.GetUInt(i), data.GetUInt(i + 1), data.GetUInt(i + 2));
+                        SetFaceAndAdvance3(facePtr, aim->mNumVertices, indexBuffer[i], indexBuffer[i + 1], indexBuffer[i + 2]);
                     }
                     break;
                 }
@@ -705,10 +746,10 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                         // The ordering is to ensure that the triangles are all drawn with the same orientation
                         if ((i + 1) % 2 == 0) {
                             // For even n, vertices n + 1, n, and n + 2 define triangle n
-                            SetFaceAndAdvance3(facePtr, aim->mNumVertices, data.GetUInt(i + 1), data.GetUInt(i), data.GetUInt(i + 2));
+                            SetFaceAndAdvance3(facePtr, aim->mNumVertices, indexBuffer[i + 1], indexBuffer[i], indexBuffer[i + 2]);
                         } else {
                             // For odd n, vertices n, n+1, and n+2 define triangle n
-                            SetFaceAndAdvance3(facePtr, aim->mNumVertices, data.GetUInt(i), data.GetUInt(i + 1), data.GetUInt(i + 2));
+                            SetFaceAndAdvance3(facePtr, aim->mNumVertices, indexBuffer[i], indexBuffer[i + 1], indexBuffer[i + 2]);
                         }
                     }
                     break;
@@ -716,9 +757,9 @@ void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
                 case PrimitiveMode_TRIANGLE_FAN:
                     nFaces = count - 2;
                     facePtr = faces = new aiFace[nFaces];
-                    SetFaceAndAdvance3(facePtr, aim->mNumVertices, data.GetUInt(0), data.GetUInt(1), data.GetUInt(2));
+                    SetFaceAndAdvance3(facePtr, aim->mNumVertices, indexBuffer[0], indexBuffer[1], indexBuffer[2]);
                     for (unsigned int i = 1; i < nFaces; ++i) {
-                        SetFaceAndAdvance3(facePtr, aim->mNumVertices, data.GetUInt(0), data.GetUInt(i + 1), data.GetUInt(i + 2));
+                        SetFaceAndAdvance3(facePtr, aim->mNumVertices, indexBuffer[0], indexBuffer[i + 1], indexBuffer[i + 2]);
                     }
                     break;
                 }
diff --git a/code/CMakeLists.txt b/code/CMakeLists.txt
index d2c59d756..6f74823df 100644
--- a/code/CMakeLists.txt
+++ b/code/CMakeLists.txt
@@ -1245,11 +1245,9 @@ IF (ASSIMP_WARNINGS_AS_ERRORS)
         -Wno-deprecated-copy-with-dtor
         -Wno-deprecated
         -Wno-format-nonliteral
-        -Wno-format-non-iso
         -Wno-comma
         -Wno-unreachable-code-break
         -Wno-unreachable-code-return
-        -Wno-unreachable-code
         -Wno-implicit-fallthrough
         -Wno-unused-template
         -Wno-undefined-func-template
diff --git a/code/Common/ImporterRegistry.cpp b/code/Common/ImporterRegistry.cpp
index 78c02d96d..c67fee936 100644
--- a/code/Common/ImporterRegistry.cpp
+++ b/code/Common/ImporterRegistry.cpp
@@ -214,7 +214,12 @@ 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.
+#if defined(WINAPI_FAMILY) && WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP
+    // not supported under uwp
     const char *envStr = std::getenv("ASSIMP_ENABLE_DEV_IMPORTERS");
+#else
+    const char *envStr = { "0" };
+#endif
     bool devImportersEnabled = envStr && strcmp(envStr, "0");
 
     // Ensure no unused var warnings if all uses are #ifndef'd away below:
@@ -377,9 +382,6 @@ void GetImporterInstanceList(std::vector<BaseImporter *> &out) {
 #ifndef ASSIMP_BUILD_NO_IQM_IMPORTER
     out.push_back(new IQMImporter());
 #endif
-    //#ifndef ASSIMP_BUILD_NO_STEP_IMPORTER
-    //    out.push_back(new StepFile::StepFileImporter());
-    //#endif
 }
 
 /** will delete all registered importers. */
diff --git a/contrib/poly2tri/poly2tri/sweep/sweep.cc b/contrib/poly2tri/poly2tri/sweep/sweep.cc
index 8e3d794c0..565a198d8 100644
--- a/contrib/poly2tri/poly2tri/sweep/sweep.cc
+++ b/contrib/poly2tri/poly2tri/sweep/sweep.cc
@@ -118,8 +118,8 @@ void Sweep::EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangl
   Point* p1 = triangle->PointCCW(point);
   Orientation o1 = Orient2d(eq, *p1, ep);
   if (o1 == COLLINEAR) {
-	  // ASSIMP_CHANGE (aramis_acg)
-	  throw std::runtime_error("EdgeEvent - collinear points not supported");
+
+
     if( triangle->Contains(&eq, p1)) {
       triangle->MarkConstrainedEdge(&eq, p1 );
       // We are modifying the constraint maybe it would be better to
@@ -137,8 +137,8 @@ void Sweep::EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangl
   Point* p2 = triangle->PointCW(point);
   Orientation o2 = Orient2d(eq, *p2, ep);
   if (o2 == COLLINEAR) {
-	  // ASSIMP_CHANGE (aramis_acg)
-	  throw std::runtime_error("EdgeEvent - collinear points not supported");
+
+
 
     if( triangle->Contains(&eq, p2)) {
       triangle->MarkConstrainedEdge(&eq, p2 );
diff --git a/include/assimp/StringUtils.h b/include/assimp/StringUtils.h
index 59c6e9ead..cd8726785 100644
--- a/include/assimp/StringUtils.h
+++ b/include/assimp/StringUtils.h
@@ -56,7 +56,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <sstream>
 #include <iomanip>
 
-#ifdef _MSC_VER
+#if defined(_MSC_VER) && !defined(__clang__)
 #define AI_SIZEFMT "%Iu"
 #else
 #define AI_SIZEFMT "%zu"
diff --git a/test/unit/utglTF2ImportExport.cpp b/test/unit/utglTF2ImportExport.cpp
index ef3fc4137..957a94b15 100644
--- a/test/unit/utglTF2ImportExport.cpp
+++ b/test/unit/utglTF2ImportExport.cpp
@@ -380,7 +380,7 @@ TEST_F(utglTF2ImportExport, importglTF2PrimitiveModeLines) {
     const aiScene *scene = importer.ReadFile(ASSIMP_TEST_MODELS_DIR "/glTF2/glTF-Asset-Generator/Mesh_PrimitiveMode/Mesh_PrimitiveMode_08.gltf", aiProcess_ValidateDataStructure);
     EXPECT_NE(nullptr, scene);
     EXPECT_EQ(scene->mMeshes[0]->mNumVertices, 4u);
-    std::array<unsigned int, 5> l1 = { { 0u, 3u, 2u, 1u, 0u } };
+    std::array<unsigned int, 5> l1 = { { 0u, 1u, 2u, 3u, 0u } };
     EXPECT_EQ(scene->mMeshes[0]->mFaces[0].mNumIndices, 2u);
     for (unsigned int i = 0; i < scene->mMeshes[0]->mNumFaces; ++i) {
         EXPECT_EQ(scene->mMeshes[0]->mFaces[i].mIndices[0], l1[i]);
@@ -394,7 +394,7 @@ TEST_F(utglTF2ImportExport, importglTF2PrimitiveModeLineLoop) {
     const aiScene *scene = importer.ReadFile(ASSIMP_TEST_MODELS_DIR "/glTF2/glTF-Asset-Generator/Mesh_PrimitiveMode/Mesh_PrimitiveMode_09.gltf", aiProcess_ValidateDataStructure);
     EXPECT_NE(nullptr, scene);
     EXPECT_EQ(scene->mMeshes[0]->mNumVertices, 4u);
-    std::array<unsigned int, 5> l1 = { { 0, 3u, 2u, 1u, 0u } };
+    std::array<unsigned int, 5> l1 = { { 0, 1u, 2u, 3u, 0u } };
     EXPECT_EQ(scene->mMeshes[0]->mFaces[0].mNumIndices, 2u);
     for (unsigned int i = 0; i < scene->mMeshes[0]->mNumFaces; ++i) {
         EXPECT_EQ(scene->mMeshes[0]->mFaces[i].mIndices[0], l1[i]);
@@ -408,7 +408,7 @@ TEST_F(utglTF2ImportExport, importglTF2PrimitiveModeLineStrip) {
     const aiScene *scene = importer.ReadFile(ASSIMP_TEST_MODELS_DIR "/glTF2/glTF-Asset-Generator/Mesh_PrimitiveMode/Mesh_PrimitiveMode_10.gltf", aiProcess_ValidateDataStructure);
     EXPECT_NE(nullptr, scene);
     EXPECT_EQ(scene->mMeshes[0]->mNumVertices, 4u);
-    std::array<unsigned int, 5> l1 = { { 0u, 3u, 2u, 1u, 0u } };
+    std::array<unsigned int, 5> l1 = { { 0u, 1u, 2u, 3u, 0u } };
     EXPECT_EQ(scene->mMeshes[0]->mFaces[0].mNumIndices, 2u);
     for (unsigned int i = 0; i < scene->mMeshes[0]->mNumFaces; ++i) {
         EXPECT_EQ(scene->mMeshes[0]->mFaces[i].mIndices[0], l1[i]);
@@ -423,13 +423,13 @@ TEST_F(utglTF2ImportExport, importglTF2PrimitiveModeTrianglesStrip) {
     EXPECT_NE(nullptr, scene);
     EXPECT_EQ(scene->mMeshes[0]->mNumFaces, 2u);
     EXPECT_EQ(scene->mMeshes[0]->mNumVertices, 4u);
-    std::array<unsigned int, 3> f1 = { { 0u, 3u, 1u } };
+    std::array<unsigned int, 3> f1 = { { 0u, 1u, 2u } };
     EXPECT_EQ(scene->mMeshes[0]->mFaces[0].mNumIndices, 3u);
     for (size_t i = 0; i < 3; ++i) {
         EXPECT_EQ(scene->mMeshes[0]->mFaces[0].mIndices[i], f1[i]);
     }
 
-    std::array<unsigned int, 3> f2 = { { 1u, 3u, 2u } };
+    std::array<unsigned int, 3> f2 = { { 2u, 1u, 3u } };
     EXPECT_EQ(scene->mMeshes[0]->mFaces[1].mNumIndices, 3u);
     for (size_t i = 0; i < 3; ++i) {
         EXPECT_EQ(scene->mMeshes[0]->mFaces[1].mIndices[i], f2[i]);
@@ -443,13 +443,13 @@ TEST_F(utglTF2ImportExport, importglTF2PrimitiveModeTrianglesFan) {
     EXPECT_NE(nullptr, scene);
     EXPECT_EQ(scene->mMeshes[0]->mNumVertices, 4u);
     EXPECT_EQ(scene->mMeshes[0]->mNumFaces, 2u);
-    std::array<unsigned int, 3> f1 = { { 0u, 3u, 2u } };
+    std::array<unsigned int, 3> f1 = { { 0u, 1u, 2u } };
     EXPECT_EQ(scene->mMeshes[0]->mFaces[0].mNumIndices, 3u);
     for (size_t i = 0; i < 3; ++i) {
         EXPECT_EQ(scene->mMeshes[0]->mFaces[0].mIndices[i], f1[i]);
     }
 
-    std::array<unsigned int, 3> f2 = { { 0u, 2u, 1u } };
+    std::array<unsigned int, 3> f2 = { { 0u, 2u, 3u } };
     EXPECT_EQ(scene->mMeshes[0]->mFaces[1].mNumIndices, 3u);
     for (size_t i = 0; i < 3; ++i) {
         EXPECT_EQ(scene->mMeshes[0]->mFaces[1].mIndices[i], f2[i]);