实现Cohen Sutherland方法对直线进行剪裁，剪裁后原来直线仍保持，可供对比。-Cohen Sutherland method to achieve a straight line to cut, cut a straight line after the original remain, which can be compared.

一个用OpenGL实现的Sutherland－Cohen裁剪算法。-use OpenGL one of Sutherland-Cohen cutting algorithm.