Merge pull request #3357 from assimp/issue_3291

Export opacity is 3DS

code/AssetLib/3DS/3DSExporter.cpp

@@ -290,12 +290,18 @@ void Discreet3DSExporter::WriteMaterials() {
             ChunkWriter curChunk(writer, Discreet3DS::CHUNK_MAT_SPECULAR);
             WriteColor(color);
         }
-
+                
         if (mat.Get(AI_MATKEY_COLOR_AMBIENT, color) == AI_SUCCESS) {
             ChunkWriter curChunk(writer, Discreet3DS::CHUNK_MAT_AMBIENT);
             WriteColor(color);
         }
 
+        float f;
+        if (mat.Get(AI_MATKEY_OPACITY, f) == AI_SUCCESS) {
+            ChunkWriter chunk(writer, Discreet3DS::CHUNK_MAT_TRANSPARENCY);
+            WritePercentChunk(1.0f - f);
+        }
+
         if (mat.Get(AI_MATKEY_COLOR_EMISSIVE, color) == AI_SUCCESS) {
             ChunkWriter curChunk(writer, Discreet3DS::CHUNK_MAT_SELF_ILLUM);
             WriteColor(color);
@@ -333,7 +339,6 @@ void Discreet3DSExporter::WriteMaterials() {
             writer.PutU2(static_cast<uint16_t>(shading_mode_out));
         }
 
-        float f;
         if (mat.Get(AI_MATKEY_SHININESS, f) == AI_SUCCESS) {
             ChunkWriter chunk(writer, Discreet3DS::CHUNK_MAT_SHININESS);
             WritePercentChunk(f);