message: clear existing world instMap
diff: @@ -87,6 +87,7 @@ namespace ospray {
  world = node.valueAs<cpp::World>();
  auto worldNode = node.nodeAs<World>();
  instMap = worldNode->instMap;
  + instMap->clear();
  } break;
  case NodeType::MATERIAL_REFERENCE:
  materialIDs.push(node.valueAs<int>());
  @@ -378,7 +379,8 @@ namespace ospray {
  // sg picking
  if (instMap && !instanceId.empty()) {
  auto ospInstance = inst.handle();
  - instMap->insert(InstanceIDMap::value_type(std::make_pair(ospInstance, instanceId)));
  + instMap->insert(
  + InstanceIDMap::value_type(std::make_pair(ospInstance, instanceId)));
  }
  };
  