To draw the section lines by turning back the ends' coordinates of the segments of the lines to be drawn.

将要画的线段端点坐标旋转还原，画出剖面线。

youdao

To draw the section lines by turning back the ends' coordinates of the segments of the lines to be drawn.

将要画的线段端点坐标旋转还原，画出剖面线。

youdao