基于两端点区域分布的线裁剪新算法

A New Line Clipping Algorithm based on Region Distribution of Two Endpoints

在确定线段完全在窗口内或某边界外初始判断后将两端点的区域分布分成6种情况进行处理.除可直接确定相交关系的情况外,一般过指定顶点在窗外作与对应边呈45度的辅助边界进一步排除完全在窗外的线段,再通过线段与指定边界相交测试确定线段与窗口的位置关系.该方法可以加快线段与窗口的求交进程,有效减少不必要的求交运算和辅助操作,显著提高裁剪效率.

The region distribution of two endpoints is divided into six kinds of cases for processing after the initial testing to determine whether a line segment is completely inside the clipping window or outside some window boundary. Except for the case that the intersection relation is determined directly,the line segments outside window is further eliminated through the 45° auxiliary boundary passing the specified vertex,and the position of a line segment in relation to window is determined by the intersection test between a line segment and the specified boundary. The new algorithm can quickly calculate the intersections between a line segment and window,avoid the unnecessary intersection calculation and auxiliary operation,and further improve the clipping efficiency.