Keep original materials names after RemoveRedundant materials process and export to collada

code/ColladaExporter.cpp

@@ -636,9 +636,24 @@ void ColladaExporter::WriteMaterials()
     const aiMaterial* mat = mScene->mMaterials[a];
 
     aiString name;
-    if( mat->Get( AI_MATKEY_NAME, name) != aiReturn_SUCCESS )
+    if( mat->Get( AI_MATKEY_NAME, name) != aiReturn_SUCCESS ) {
       name = "mat";
       materials[a].name = std::string( "m") + to_string(a) + name.C_Str();
+    } else {
+      // try to use the material's name if no other material has already taken it, else append #
+      std::string testName = name.C_Str();
+      size_t materialCountWithThisName = 0;
+      for( size_t i = 0; i < a; i ++ ) {
+        if( materials[i].name == testName ) {
+          materialCountWithThisName ++;
+        }
+      }
+      if( materialCountWithThisName == 0 ) {
+        materials[a].name = name.C_Str();
+      } else {
+        materials[a].name = std::string(name.C_Str()) + to_string(materialCountWithThisName);  
+      }
+    }
     for( std::string::iterator it = materials[a].name.begin(); it != materials[a].name.end(); ++it ) {
       if( !isalnum_C( *it ) ) {
         *it = '_';

code/RemoveRedundantMaterials.cpp

@@ -177,12 +177,14 @@ void RemoveRedundantMatsProcess::Execute( aiScene* pScene)
                     continue;
                 }
 
-                // generate new names for all modified materials
+                // generate new names for modified materials that had no names
                 const unsigned int idx = aiMappingTable[p];
                 if (ppcMaterials[idx]) {
                     aiString sz;
+                    if( ppcMaterials[idx]->Get(AI_MATKEY_NAME, sz) != AI_SUCCESS ) {
                         sz.length = ::ai_snprintf(sz.data,MAXLEN,"JoinedMaterial_#%u",p);
                         ((aiMaterial*)ppcMaterials[idx])->AddProperty(&sz,AI_MATKEY_NAME);
+                    }
                 } else {
                     ppcMaterials[idx] = pScene->mMaterials[p];
                 }