switch (FEAT_TRAINS,SELF, switch_hopper_wagon_layers, [

  STORE_TEMP((getbits(extra_callback_info1, 8, 8) < 4 ? CB_FLAG_MORE_SPRITES  : 0) + PALETTE_USE_DEFAULT, 0x100),

  getbits(extra_callback_info1, 8, 8)

  ]){

  0: spriteset_wagon_wheel;

  1: spriteset_hopper_wagon_back;

  2: spriteset_hopper_wagon_cargo;

  3: spriteset_hopper_wagon_front;

  return spriteset_hopper_wagon_back;

}