switch (FEAT_OBJECTS, SELF, object_decide_tilepos, relative_coord(relative_x,relative_y)) {
    relative_coord(0,0): graphics_object_tile_00;
    relative_coord(1,0): graphics_object_tile_10;
}

item(FEAT_OBJECTS, my_object) {

	property {
        (...)
	}
	graphics {
		object_decide_tilepos;
	}
}