atx = cx*tiles_per_chunk + get_tx(); aty = cy*tiles_per_chunk + get_ty();
atx = cx*c_tiles_per_chunk + get_tx(); aty = cy*c_tiles_per_chunk + get_ty();
	void get_abs_tile(int& atx, int& aty, int& atz) const		{		atz = get_lift();		atx = cx*tiles_per_chunk + get_tx();		aty = cy*tiles_per_chunk + get_ty();		}