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 connectivity connectivity) Cohen-Sutherland clipping algorithm to achieve the midpoint of the two-dimensional linear cut and split clipping algorithm