一个有效的多边形裁剪算法，介绍了概念、数据结构、算法、交点判断等

主要是对图形进行裁剪，裁剪分为两类，一类是线段裁剪，另一类是多边形裁剪-Mainly to cut graphics, tailoring can be divided into two kinds, one kind is line cutting, another kind is polygon clipping

　　实现二维扫描转换多边形的扫描线算法 　　实现二维连通区域填充的种子填充算法（四连通或八连通） 　　实现二维直线段裁剪的Cohen-Sutherland裁剪算法和中点分割裁剪算法 -Realization of two-dimensional polygon scan conversion algorithm dimensional scan line connected region filled seed filling algorithm (four or eight con