//滑车
        box_slider = new osg::Box(
            osg::Vec3(center_x + tower_width*(14.0f), center_y, index_z - tower_height*1.4f + column_width*4.0f), 
            tower_width*1.0f, 
            tower_length*1.0f, 
            tower_height*0.2f);