Redefine deprecated glTF-specific PBR material macros

Intended to support Qt5 QtQuick3D until it is ported to generic PBR
macros.

code/AssetLib/glTF2/glTF2Asset.h

@@ -113,6 +113,8 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 // clang-format on
 
 #include <assimp/StringUtils.h>
+#include <assimp/material.h>
+#include <assimp/GltfMaterial.h>
 
 #include "AssetLib/glTF/glTFCommon.h"
 
@@ -140,7 +142,6 @@ using glTFCommon::vec4;
 
 //! Magic number for GLB files
 #define AI_GLB_MAGIC_NUMBER "glTF"
-#include <assimp/pbrmaterial.h>
 
 #ifdef ASSIMP_API
 #include <assimp/Compiler/pushpack1.h>

code/AssetLib/glTF2/glTF2Importer.cpp

@@ -299,6 +299,7 @@ static aiMaterial *ImportMaterial(std::vector<int> &embeddedTexIdxs, Asset &r, M
         // glTFv2 is either PBR or Unlit
         aiShadingMode shadingMode = aiShadingMode_PBR_BRDF;
         if (mat.unlit) {
+            aimat->AddProperty(&mat.unlit, 1, "$mat.gltf.unlit", 0, 0); // TODO: Remove this property, it is kept for backwards compatibility with assimp 5.0.1
             shadingMode = aiShadingMode_Unlit;
         }
 

code/CMakeLists.txt

@@ -79,6 +79,7 @@ SET( PUBLIC_HEADERS
   ${HEADER_PATH}/matrix4x4.inl
   ${HEADER_PATH}/mesh.h
   ${HEADER_PATH}/pbrmaterial.h
+  ${HEADER_PATH}/GltfMaterial.h
   ${HEADER_PATH}/postprocess.h
   ${HEADER_PATH}/quaternion.h
   ${HEADER_PATH}/quaternion.inl