message: don't add vertex.normal or vertex.texcoord if they are empty
diff: @@ -118,9 +118,6 @@ namespace ospray::sg {
  std::string baseName = file.name() + '_';
  for (auto &shape : objData.shapes) {
  - auto name = baseName + std::to_string(shapeId++) + '_' + shape.name;
  - auto &mesh = createChild(name, "geometry_triangles");
  -
  auto numSrcIndices = shape.mesh.indices.size();
  std::vector<vec3f> v;
  @@ -161,10 +158,15 @@ namespace ospray::sg {
  vt.emplace_back(&attrib.texcoords[idx.texcoord_index * 2]);
  }
  + auto name = baseName + std::to_string(shapeId++) + '_' + shape.name;
  + auto &mesh = createChild(name, "geometry_triangles");
  +
  mesh.createChildData("vertex.position", v);
  + mesh.createChildData("index", vi);
  + if (!vn.empty())
  mesh.createChildData("vertex.normal", vn);
  + if (!vt.empty())
  mesh.createChildData("vertex.texcoord", vt);
  - mesh.createChildData("index", vi);
  }
  std::cout << "...finished import!\n";
  