说明：  1、理解多边形裁剪的原理（Weiler-Atherton算法、Sutherland-Hodgeman栋算法）。 2、实现这两种多边形的裁剪算法，在屏幕上用一个封闭矩形裁剪任意多边形（凹多边形、凸多边形都要实验）。 3、编写上述算法程序，在工作区域当中运行并显示算法效果。 4、将多边形裁剪模块添加到设计的图形实验系统当中。 5、完成代码编写、调试。
(1, understand the principles of polygon clipping (Weiler-Atherton algorithm, Sutherland-Hodgeman buildings algorithm). 2, to achieve these two polygon clipping algorithm, on the screen with a closed arbitrary polygon clipping rectangle (concave polygon convex polygon should experiment). 3, the preparation of the above algorithm program, which runs in the work area and display algorithm results. 4. Add the polygon clipping module to which the graphics test system design. 5, complete coding, debugging.)