Make Blender importer aware of collections, and use them when available. Also add the default startup file for Blender 2.93

code/AssetLib/Blender/BlenderLoader.cpp

@@ -318,13 +318,54 @@ void BlenderImporter::ExtractScene(Scene &out, const FileDatabase &file) {
 #endif
 }
 
+// ------------------------------------------------------------------------------------------------
+void BlenderImporter::ParseSubCollection(const Blender::Scene &in, aiNode *root, std::shared_ptr<Collection> collection, ConversionData &conv_data) {
+
+    std::deque<Object *> root_objects;
+    // Count number of objects
+    for (std::shared_ptr<CollectionObject> cur = std::static_pointer_cast<CollectionObject>(collection->gobject.first); cur; cur = cur->next) {
+        if (cur->ob) {
+            root_objects.push_back(cur->ob.get());
+        }
+    }
+    std::deque<Collection *> root_children;
+    // Count number of child nodes
+    for (std::shared_ptr<CollectionChild> cur = std::static_pointer_cast<CollectionChild>(collection->children.first); cur; cur = cur->next) {
+        if (cur->collection) {
+            root_children.push_back(cur->collection.get());
+        }
+    }
+    root->mNumChildren = static_cast<unsigned int>(root_objects.size() + root_children.size());
+    root->mChildren = new aiNode *[root->mNumChildren]();
+
+    for (unsigned int i = 0; i < static_cast<unsigned int>(root_objects.size()); ++i) {
+        root->mChildren[i] = ConvertNode(in, root_objects[i], conv_data, aiMatrix4x4());
+        root->mChildren[i]->mParent = root;
+    }
+
+    // For each subcollection create a new node to represent it
+    unsigned int iterator = static_cast<unsigned int>(root_objects.size());
+    for (std::shared_ptr<CollectionChild> cur = std::static_pointer_cast<CollectionChild>(collection->children.first); cur; cur = cur->next) {
+        if (cur->collection) {
+            root->mChildren[iterator] = new aiNode(cur->collection->id.name + 2); // skip over the name prefix 'OB'
+            root->mChildren[iterator]->mParent = root;
+            ParseSubCollection(in, root->mChildren[iterator], cur->collection, conv_data);
+        }
+        iterator += 1;
+    }
+    // Worst function I've ever written
+}
+
 // ------------------------------------------------------------------------------------------------
 void BlenderImporter::ConvertBlendFile(aiScene *out, const Scene &in, const FileDatabase &file) {
     ConversionData conv(file);
 
-    // FIXME it must be possible to take the hierarchy directly from
-    // the file. This is terrible. Here, we're first looking for
-    // all objects which don't have parent objects at all -
+    aiNode *root = out->mRootNode = new aiNode("<BlenderRoot>");
+    // Iterate over all objects directly under master_collection,
+    // If in.master_collection == null, then we're parsing something older.
+    if (in.master_collection) {
+        ParseSubCollection(in, root, in.master_collection, conv);
+    } else {
         std::deque<const Object *> no_parents;
         for (std::shared_ptr<Base> cur = std::static_pointer_cast<Base>(in.base.first); cur; cur = cur->next) {
             if (cur->object) {
@@ -347,14 +388,13 @@ void BlenderImporter::ConvertBlendFile(aiScene *out, const Scene &in, const File
             ThrowException("Expected at least one object with no parent");
         }
 
-    aiNode *root = out->mRootNode = new aiNode("<BlenderRoot>");
-
         root->mNumChildren = static_cast<unsigned int>(no_parents.size());
         root->mChildren = new aiNode *[root->mNumChildren]();
         for (unsigned int i = 0; i < root->mNumChildren; ++i) {
             root->mChildren[i] = ConvertNode(in, no_parents[i], conv, aiMatrix4x4());
             root->mChildren[i]->mParent = root;
         }
+    }
 
     BuildMaterials(conv);
 

code/AssetLib/Blender/BlenderLoader.h

@@ -78,6 +78,7 @@ struct ElemBase;
 namespace Blender {
 struct Scene;
 struct Object;
+struct Collection;
 struct Mesh;
 struct Camera;
 struct Lamp;
@@ -116,6 +117,7 @@ protected:
     void InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) override;
     void ParseBlendFile(Blender::FileDatabase &out, std::shared_ptr<IOStream> stream);
     void ExtractScene(Blender::Scene &out, const Blender::FileDatabase &file);
+    void ParseSubCollection(const Blender::Scene &in, aiNode *root, std::shared_ptr<Blender::Collection> collection, Blender::ConversionData &conv_data);
     void ConvertBlendFile(aiScene *out, const Blender::Scene &in, const Blender::FileDatabase &file);
 
 private:

code/AssetLib/Blender/BlenderScene.cpp

@@ -94,6 +94,43 @@ void Structure ::Convert<Group>(
     db.reader->IncPtr(size);
 }
 
+//--------------------------------------------------------------------------------
+template <>
+void Structure::Convert<CollectionObject>(
+        CollectionObject &dest,
+        const FileDatabase &db) const {
+
+    ReadFieldPtr<ErrorPolicy_Fail>(dest.prev, "*prev", db);
+    ReadFieldPtr<ErrorPolicy_Fail>(dest.next, "*next", db);
+    ReadFieldPtr<ErrorPolicy_Igno>(dest.ob, "*ob", db);
+}
+
+//--------------------------------------------------------------------------------
+template <>
+void Structure::Convert<CollectionChild>(
+        CollectionChild &dest,
+        const FileDatabase &db) const {
+
+    ReadFieldPtr<ErrorPolicy_Fail>(dest.prev, "*prev", db);
+    ReadFieldPtr<ErrorPolicy_Fail>(dest.next, "*next", db);
+    ReadFieldPtr<ErrorPolicy_Igno>(dest.collection, "*collection", db);
+
+    db.reader->IncPtr(size);
+}
+
+//--------------------------------------------------------------------------------
+template <>
+void Structure::Convert<Collection>(
+        Collection &dest,
+        const FileDatabase &db) const {
+
+    ReadField<ErrorPolicy_Fail>(dest.id, "id", db);
+    ReadField<ErrorPolicy_Fail>(dest.gobject, "gobject", db);
+    ReadField<ErrorPolicy_Fail>(dest.children, "children", db);
+
+    db.reader->IncPtr(size);
+}
+
 //--------------------------------------------------------------------------------
 template <>
 void Structure ::Convert<MTex>(
@@ -660,6 +697,7 @@ void Structure ::Convert<Scene>(
     ReadFieldPtr<ErrorPolicy_Warn>(dest.camera, "*camera", db);
     ReadFieldPtr<ErrorPolicy_Warn>(dest.world, "*world", db);
     ReadFieldPtr<ErrorPolicy_Warn>(dest.basact, "*basact", db);
+    ReadFieldPtr<ErrorPolicy_Warn>(dest.master_collection, "*master_collection", db);
     ReadField<ErrorPolicy_Igno>(dest.base, "base", db);
 
     db.reader->IncPtr(size);
@@ -833,6 +871,9 @@ void DNA::RegisterConverters() {
     converters["Image"] = DNA::FactoryPair(&Structure::Allocate<Image>, &Structure::Convert<Image>);
     converters["CustomData"] = DNA::FactoryPair(&Structure::Allocate<CustomData>, &Structure::Convert<CustomData>);
     converters["CustomDataLayer"] = DNA::FactoryPair(&Structure::Allocate<CustomDataLayer>, &Structure::Convert<CustomDataLayer>);
+    converters["Collection"] = DNA::FactoryPair(&Structure::Allocate<Collection>, &Structure::Convert<Collection>);
+    converters["CollectionChild"] = DNA::FactoryPair(&Structure::Allocate<CollectionChild>, &Structure::Convert<CollectionChild>);
+    converters["CollectionObject"] = DNA::FactoryPair(&Structure::Allocate<CollectionObject>, &Structure::Convert<CollectionObject>);
 }
 
 #endif // ASSIMP_BUILD_NO_BLEND_IMPORTER

code/AssetLib/Blender/BlenderScene.h

@@ -147,6 +147,26 @@ struct Group : ElemBase {
     std::shared_ptr<GroupObject> gobject;
 };
 
+// -------------------------------------------------------------------------------
+struct Collection : ElemBase {
+    ID id FAIL;
+    ListBase gobject; // CollectionObject
+    ListBase children; // CollectionChild
+    //ListBase objects; // Objects
+};
+
+// -------------------------------------------------------------------------------
+struct CollectionObject : ElemBase {
+    std::shared_ptr<CollectionObject> next, prev;
+    std::shared_ptr<Object> ob;
+};
+
+// -------------------------------------------------------------------------------
+struct CollectionChild : ElemBase {
+    std::shared_ptr<CollectionChild> next, prev;
+    std::shared_ptr<Collection> collection;
+};
+
 // -------------------------------------------------------------------------------
 struct World : ElemBase {
     ID id FAIL;
@@ -729,11 +749,12 @@ struct Scene : ElemBase {
     std::shared_ptr<Object> camera WARN;
     std::shared_ptr<World> world WARN;
     std::shared_ptr<Base> basact WARN;
+    std::shared_ptr<Collection> master_collection WARN;
 
     ListBase base;
 
     Scene() :
-            ElemBase(), camera(), world(), basact() {
+            ElemBase(), camera(), world(), basact(), master_collection() {
         // empty
     }
 };

code/AssetLib/Blender/BlenderSceneGen.h

@@ -62,6 +62,12 @@ template <> void Structure :: Convert<Group> (
     ) const
 ;
 
+template <> void Structure::Convert<Collection>(
+    Collection& dest,
+    const FileDatabase& db
+    ) const
+;
+
 template <> void Structure :: Convert<MTex> (
     MTex& dest,
     const FileDatabase& db