绘制点、线、三角形等基本对象，设定投影关系，确定窗口大小与视口大小，通过改变顶点坐标位置，观察物体绘制结果的变化，并与实际计算的结果相对照；通过改变顶点位置，设计针对直线的完全裁剪、一端部分裁剪，中间部分裁剪三种情况，并观察响应的结果；设计针对面的不同裁剪情况。-Draw points, lines, triangles and other basic objects, set projection relation to determine the window size and viewpo

计算点与面的关系，点与线的关系，在水域边界处理，地图边界自由裁剪方面可以借鉴(The relationship between point and surface and the relationship between point and line can be calculated. It can be used for reference in dealing with boundary of water area and free cutting of map boundaries.)