实验四 编程实现Cohen-Sutherland线段裁剪算法或者Sutherland-Hodgman多边形裁剪算法 对各种情况进行测试，验证算法实现的完整性 -Experiments four programming Cohen-Sutherland line clipping algorithm or Sutherland-Hodgman polygon clipping algorithms for testing a variety of situations, to ver