Manually read alphaMode material property

code/glTF2Exporter.cpp

@@ -424,7 +424,20 @@ void glTF2Exporter::ExportMaterials()
         mat->Get(AI_MATKEY_TWOSIDED, m->doubleSided);
         mat->Get(AI_MATKEY_GLTF_ALPHACUTOFF, m->alphaCutoff);
 
-        if (mat->Get(AI_MATKEY_GLTF_ALPHAMODE, m->alphaMode) != AI_SUCCESS) {
+        bool foundAlphaMode = false;
+        for (size_t i = 0; i < mat->mNumProperties; ++i) {
+            aiMaterialProperty *prop = mat->mProperties[i];
+            if (prop->mKey != aiString("$mat.gltf.alphaMode"))
+                continue;
+
+            std::string alphaMode;
+            for (size_t c = 0; c < prop->mDataLength; ++c)
+                alphaMode += prop->mData[c];
+            m->alphaMode = alphaMode;
+            foundAlphaMode = true;
+        }
+
+        if (!foundAlphaMode) {
             float opacity;
 
             if (mat->Get(AI_MATKEY_OPACITY, opacity) == AI_SUCCESS) {
@@ -435,7 +448,7 @@ void glTF2Exporter::ExportMaterials()
             }
         }
 
-        bool hasPbrSpecularGlossiness;
+        bool hasPbrSpecularGlossiness = false;
         mat->Get(AI_MATKEY_GLTF_PBRSPECULARGLOSSINESS, hasPbrSpecularGlossiness);
 
         if (hasPbrSpecularGlossiness) {