/// get_floor_material()
// leaks `bl_id`
bl_id = instance_position(x, y + 8, oSolid);
if (bl_id < 0) bl_id = instance_position(x + 6, y + 2, oSolid);
if (bl_id < 0) bl_id = instance_position(x - 6, y + 2, oSolid);
if (bl_id > 0) {
    return bl_id.material;
} else return 0;