glTF2 Importer Update.

Vertex weights are now correctly assigned for skinned meshes. Portions of the vertex weight fix were taken from: https://github.com/ConfettiFX/The-Forge/blob/master/Common_3/ThirdParty/OpenSource/assimp/4.1.0/code/glTF2Importer.cpp#L823-L860.
Inverse bind matrices have been adjusted to be consistent with the other importers.
All nodes, joints and meshes are now named so T3D can cross reference when loading animations.
All T3D specific changes have been bracketed in //T3D_CHANGE_BEGIN and //T3D_CHANGE_END tags to make them easier to find when the assimp library is updated.

Engine/lib/assimp/code/glTF2Asset.inl

@@ -405,8 +405,10 @@ inline void Buffer::Read(Value& obj, Asset& r)
 inline bool Buffer::LoadFromStream(IOStream& stream, size_t length, size_t baseOffset)
 {
     byteLength = length ? length : stream.FileSize();
+    //T3D_CHANGE_BEGIN
     if ((byteLength + baseOffset) > stream.FileSize())
        byteLength = stream.FileSize() - baseOffset;
+    //T3D_CHANGE_END
 
     if (baseOffset) {
         stream.Seek(baseOffset, aiOrigin_SET);

Engine/lib/assimp/code/glTF2Importer.cpp

@@ -822,8 +822,6 @@ aiNode* ImportNode(aiScene* pScene, glTF2::Asset& r, std::vector<unsigned int>&
         if (node.skin) {
             for (int primitiveNo = 0; primitiveNo < count; ++primitiveNo) {
                 aiMesh* mesh = pScene->mMeshes[meshOffsets[mesh_idx]+primitiveNo];
-                mesh->mNumBones = static_cast<unsigned int>(node.skin->jointNames.size());
-                mesh->mBones = new aiBone*[mesh->mNumBones];
 
                 // GLTF and Assimp choose to store bone weights differently.
                 // GLTF has each vertex specify which bones influence the vertex.
@@ -834,39 +832,98 @@ aiNode* ImportNode(aiScene* pScene, glTF2::Asset& r, std::vector<unsigned int>&
                 // both because it's somewhat slow and because, for many applications,
                 // we then need to reconvert the data back into the vertex-to-bone
                 // mapping which makes things doubly-slow.
-                std::vector<std::vector<aiVertexWeight>> weighting(mesh->mNumBones);
+
+                //T3D_CHANGE_BEGIN
+                // The following commented block has been completely replaced.
+                // Portions of the replacement code block have been taken from:
+                // https://github.com/ConfettiFX/The-Forge/blob/master/Common_3/ThirdParty/OpenSource/assimp/4.1.0/code/glTF2Importer.cpp#L823-L860
+                //std::vector<std::vector<aiVertexWeight>> weighting(mesh->mNumBones);
+                //BuildVertexWeightMapping(node.meshes[0]->primitives[primitiveNo], weighting);
+
+                //for (uint32_t i = 0; i < mesh->mNumBones; ++i) {
+                //    aiBone* bone = new aiBone();
+
+                //    Ref<Node> joint = node.skin->jointNames[i];
+                //    if (!joint->name.empty()) {
+                //      bone->mName = joint->name;
+                //    } else {
+                //      // Assimp expects each bone to have a unique name.
+                //      static const std::string kDefaultName = "bone_";
+                //      char postfix[10] = {0};
+                //      ASSIMP_itoa10(postfix, i);
+                //      bone->mName = (kDefaultName + postfix);
+                //    }
+                //    GetNodeTransform(bone->mOffsetMatrix, *joint);
+
+                //    std::vector<aiVertexWeight>& weights = weighting[i];
+
+                //    bone->mNumWeights = static_cast<uint32_t>(weights.size());
+                //    if (bone->mNumWeights > 0) {
+                //      bone->mWeights = new aiVertexWeight[bone->mNumWeights];
+                //      memcpy(bone->mWeights, weights.data(), bone->mNumWeights * sizeof(aiVertexWeight));
+                //    } else {
+                //      // Assimp expects all bones to have at least 1 weight.
+                //      bone->mWeights = new aiVertexWeight[1];
+                //      bone->mNumWeights = 1;
+                //      bone->mWeights->mVertexId = 0;
+                //      bone->mWeights->mWeight = 0.f;
+                //    }
+                //    mesh->mBones[i] = bone;
+
+                std::vector<std::vector<aiVertexWeight>> weighting(node.skin->jointNames.size());
                 BuildVertexWeightMapping(node.meshes[0]->primitives[primitiveNo], weighting);
 
-                for (uint32_t i = 0; i < mesh->mNumBones; ++i) {
-                    aiBone* bone = new aiBone();
-
-                    Ref<Node> joint = node.skin->jointNames[i];
-                    if (!joint->name.empty()) {
-                      bone->mName = joint->name;
-                    } else {
-                      // Assimp expects each bone to have a unique name.
-                      static const std::string kDefaultName = "bone_";
-                      char postfix[10] = {0};
-                      ASSIMP_itoa10(postfix, i);
-                      bone->mName = (kDefaultName + postfix);
-                    }
-                    GetNodeTransform(bone->mOffsetMatrix, *joint);
-
-                    std::vector<aiVertexWeight>& weights = weighting[i];
-
-                    bone->mNumWeights = static_cast<uint32_t>(weights.size());
-                    if (bone->mNumWeights > 0) {
-                      bone->mWeights = new aiVertexWeight[bone->mNumWeights];
-                      memcpy(bone->mWeights, weights.data(), bone->mNumWeights * sizeof(aiVertexWeight));
-                    } else {
-                      // Assimp expects all bones to have at least 1 weight.
-                      bone->mWeights = new aiVertexWeight[1];
-                      bone->mNumWeights = 1;
-                      bone->mWeights->mVertexId = 0;
-                      bone->mWeights->mWeight = 0.f;
+                // CONFFX_BEGIN
+                // Assimp doesn't support bones with no weight. We have to count the
+                // number of bones that affect the mesh and limit it to just those bones.
+                int numBones = 0;
+                for (size_t i = 0; i < node.skin->jointNames.size(); ++i) {
+                    if (!weighting[i].empty())
+                        ++numBones;
+                }
+
+                mesh->mNumBones = numBones;
+                if (numBones > 0)
+                {
+                    mesh->mBones = new aiBone*[mesh->mNumBones];
+
+                    int j = 0;
+                    for (size_t i = 0; i < node.skin->jointNames.size(); ++i) {
+                        if (!weighting[i].empty())
+                        {
+                            aiBone* bone = new aiBone();
+
+                            Ref<Node> joint = node.skin->jointNames[i];
+                            bone->mName = joint->name.empty() ? joint->id : joint->name;
+
+                            // Get the inverseBindMatrix for the joint, grab the position out of row 4,
+                            // invert the matrix and put the position back as column 4.
+                            aiMatrix4x4 *tmpMat;
+                            uint8_t *matPtr = node.skin->inverseBindMatrices->GetPointer();
+                            tmpMat = (aiMatrix4x4*)matPtr;
+                            bone->mOffsetMatrix = tmpMat[i];
+                            aiVector3D tmpPos(bone->mOffsetMatrix.d1, bone->mOffsetMatrix.d2, bone->mOffsetMatrix.d3);
+                            bone->mOffsetMatrix.d1 = bone->mOffsetMatrix.d2 = bone->mOffsetMatrix.d3 = 0.0;
+                            bone->mOffsetMatrix.Inverse();
+                            bone->mOffsetMatrix.a4 = tmpPos.x;
+                            bone->mOffsetMatrix.b4 = tmpPos.y;
+                            bone->mOffsetMatrix.c4 = tmpPos.z;
+
+                            std::vector<aiVertexWeight>& weights = weighting[i];
+
+                            bone->mNumWeights = static_cast<uint32_t>(weights.size());
+                            if (bone->mNumWeights > 0) {
+                              bone->mWeights = new aiVertexWeight[bone->mNumWeights];
+                              memcpy(bone->mWeights, weights.data(), bone->mNumWeights * sizeof(aiVertexWeight));
+                            }
+                            mesh->mBones[j++] = bone;
+                        }
                     }
-                    mesh->mBones[i] = bone;
                 }
+                else
+                    mesh->mBones = nullptr;
+                // CONFFX_END
+                //T3D_CHANGE_END
             }
         }
 
@@ -921,7 +978,10 @@ struct AnimationSamplers {
 aiNodeAnim* CreateNodeAnim(glTF2::Asset& r, Node& node, AnimationSamplers& samplers)
 {
     aiNodeAnim* anim = new aiNodeAnim();
-    anim->mNodeName = node.name;
+    //T3D_CHANGE_BEGIN
+    //anim->mNodeName = node.name;
+    anim->mNodeName = node.name.empty() ? node.id : node.name;
+    //T3D_CHANGE_END
 
     static const float kMillisecondsFromSeconds = 1000.f;
 
@@ -1042,15 +1102,27 @@ void glTF2Importer::ImportAnimations(glTF2::Asset& r)
 
         std::unordered_map<unsigned int, AnimationSamplers> samplers = GatherSamplers(anim);
 
-        ai_anim->mNumChannels = static_cast<uint32_t>(samplers.size());
+        //T3D_CHANGE_BEGIN
+        //ai_anim->mNumChannels = static_cast<uint32_t>(samplers.size());
+        //if (ai_anim->mNumChannels > 0) {
+        //    ai_anim->mChannels = new aiNodeAnim*[ai_anim->mNumChannels];
+        //    int j = 0;
+        //    for (auto& iter : samplers) {
+        //        ai_anim->mChannels[j] = CreateNodeAnim(r, r.nodes[iter.first], iter.second);
+        //        ++j;
+        //    }
+        //}
+
+        ai_anim->mNumChannels = r.skins.Size() > 0 ? r.skins[0].jointNames.size() : 0;
         if (ai_anim->mNumChannels > 0) {
             ai_anim->mChannels = new aiNodeAnim*[ai_anim->mNumChannels];
             int j = 0;
-            for (auto& iter : samplers) {
-                ai_anim->mChannels[j] = CreateNodeAnim(r, r.nodes[iter.first], iter.second);
+            for (auto& iter : r.skins[0].jointNames) {
+                ai_anim->mChannels[j] = CreateNodeAnim(r, *iter, samplers[iter.GetIndex()]);
                 ++j;
             }
         }
+        //T3D_CHANGE_END
 
         // Use the latest keyframe for the duration of the animation
         double maxDuration = 0;

Engine/lib/assimp/code/glTFAsset.inl

@@ -345,8 +345,10 @@ inline void Buffer::Read(Value& obj, Asset& r)
 inline bool Buffer::LoadFromStream(IOStream& stream, size_t length, size_t baseOffset)
 {
     byteLength = length ? length : stream.FileSize();
+    //T3D_CHANGE_BEGIN
     if ((byteLength + baseOffset) > stream.FileSize())
        byteLength = stream.FileSize() - baseOffset;
+    //T3D_CHANGE_END
 
     if (baseOffset) {
         stream.Seek(baseOffset, aiOrigin_SET);