message: Enable device to host BVH copies
diff: @@ -2561,7 +2561,7 @@ void renderer::on_key_press(key_event const& event)
  {
  rt.mode() = host_device_rt::CPU;
  - /*if (host_bvhs.empty())
  + if (host_bvhs.empty())
  {
  copy_bvhs(
  host_bvhs,
  @@ -2570,7 +2570,7 @@ void renderer::on_key_press(key_event const& event)
  device_top_level_bvh,
  DeviceToHost
  );
  - }*/
  + }
  }
  counter.reset();
  clear_frame();
  