Merge branch 'master' into fix_memory_leak_in_gltf2_on_exception

code/glTF2/glTF2Asset.h

@@ -1034,6 +1034,12 @@ namespace glTF2
 			bool KHR_texture_transform;
         } extensionsUsed;
 
+        //! Keeps info about the required extensions
+        struct RequiredExtensions
+        {
+            bool KHR_draco_mesh_compression;
+        } extensionsRequired;
+
         AssetMetadata asset;
 
 
@@ -1076,6 +1082,7 @@ namespace glTF2
             , textures      (*this, "textures")
         {
             memset(&extensionsUsed, 0, sizeof(extensionsUsed));
+            memset(&extensionsRequired, 0, sizeof(extensionsRequired));
         }
 
         //! Main function
@@ -1094,6 +1101,7 @@ namespace glTF2
         void ReadBinaryHeader(IOStream& stream, std::vector<char>& sceneData);
 
         void ReadExtensionsUsed(Document& doc);
+        void ReadExtensionsRequired(Document& doc);
 
         IOStream* OpenFile(std::string path, const char* mode, bool absolute = false);
     };

code/glTF2/glTF2Asset.inl

@@ -1433,6 +1433,12 @@ inline void Asset::Load(const std::string& pFile, bool isBinary)
     // Load the metadata
     asset.Read(doc);
     ReadExtensionsUsed(doc);
+    ReadExtensionsRequired(doc);
+
+    // Currently Draco is not supported
+    if (extensionsRequired.KHR_draco_mesh_compression) {
+        throw DeadlyImportError("GLTF: Draco mesh compression not currently supported.");
+    }
 
     // Prepare the dictionaries
     for (size_t i = 0; i < mDicts.size(); ++i) {
@@ -1479,6 +1485,29 @@ inline void Asset::SetAsBinary()
     }
 }
 
+// As required extensions are only a concept in glTF 2.0, this is here
+// instead of glTFCommon.h
+#define CHECK_REQUIRED_EXT(EXT) \
+	if (exts.find(#EXT) != exts.end()) extensionsRequired.EXT = true;
+
+inline void Asset::ReadExtensionsRequired(Document& doc)
+{
+    Value* extsRequired = FindArray(doc, "extensionsRequired");
+    if (nullptr == extsRequired) {
+	return;
+    }
+
+    std::gltf_unordered_map<std::string, bool> exts;
+    for (unsigned int i = 0; i < extsRequired->Size(); ++i) {
+        if ((*extsRequired)[i].IsString()) {
+            exts[(*extsRequired)[i].GetString()] = true;
+        }
+    }
+
+    CHECK_REQUIRED_EXT(KHR_draco_mesh_compression);
+
+    #undef CHECK_REQUIRED_EXT
+}
 
 inline void Asset::ReadExtensionsUsed(Document& doc)
 {

code/glTF2/glTF2Importer.cpp

@@ -204,11 +204,21 @@ inline void SetMaterialTextureProperty(std::vector<int> &embeddedTexIdxs, Asset
 
 		if (prop.textureTransformSupported) {
 			aiUVTransform transform;
-			transform.mTranslation.x = prop.TextureTransformExt_t.offset[0];
-			transform.mTranslation.y = prop.TextureTransformExt_t.offset[0];
-			transform.mRotation = prop.TextureTransformExt_t.rotation;
 			transform.mScaling.x = prop.TextureTransformExt_t.scale[0];
 			transform.mScaling.y = prop.TextureTransformExt_t.scale[1];
+			transform.mRotation = -prop.TextureTransformExt_t.rotation; // must be negated
+
+			// A change of coordinates is required to map glTF UV transformations into the space used by
+			// Assimp. In glTF all UV origins are at 0,1 (top left of texture) in Assimp space. In Assimp
+			// rotation occurs around the image center (0.5,0.5) where as in glTF rotation is around the
+			// texture origin. All three can be corrected for solely by a change of the translation since
+			// the transformations available are shape preserving. Note the importer already flips the V
+			// coordinate of the actual meshes during import.
+			const ai_real rcos(cos(-transform.mRotation));
+			const ai_real rsin(sin(-transform.mRotation));
+			transform.mTranslation.x = (0.5 * transform.mScaling.x) * (-rcos + rsin + 1) + prop.TextureTransformExt_t.offset[0];
+			transform.mTranslation.y = ((0.5 * transform.mScaling.y) * (rsin + rcos - 1)) + 1 - transform.mScaling.y - prop.TextureTransformExt_t.offset[1];;
+
 			mat->AddProperty(&transform, 1, _AI_MATKEY_UVTRANSFORM_BASE, texType, texSlot);
 		}