学习计算机图形学的学生必做的一个题目，本人自认做的比较完美，会对其他同学有点借鉴意义，实现橡皮颈画任意多边形，对其进行填充-study computer graphics students will do a topic, I do a self perfection, the other students would somewhat useful to achieve rubber neck painting arbitrary polygon, its filling