message: Defer host to device BVH copies
  TODO: can do the same for the remaining data items, too!
diff: @@ -2874,7 +2874,7 @@ int main(int argc, char** argv)
  // Copy data to GPU
  try
  {
  - if (rend.build_strategy != renderer::LBVH)
  + if (rend.rt.mode() == host_device_rt::GPU && rend.build_strategy != renderer::LBVH)
  {
  rend.copy_bvhs(
  rend.device_bvhs,
  @@ -2885,6 +2885,8 @@ int main(int argc, char** argv)
  );
  }
  + // TODO: similar to BVH uploads, when we're not yet rendering on
  + // the device, we could defer this, too!
  rend.device_geometric_normals = rend.mod.geometric_normals;
  rend.device_shading_normals = rend.mod.shading_normals;
  rend.device_tex_coords = rend.mod.tex_coords;
  