size_t data_size = wd*get_pixel_size(storage_fmt);
void *staging = device.get_transfer_queue().prepare_transfer(this, false, data_size,
[this, level, discard](){
size_t data_size = wd*get_pixel_size(storage_fmt);
void *staging = device.get_transfer_queue().prepare_transfer(this, false, data_size,
[this, level, discard](){