一种基于截距的圆形窗口线裁剪算法  

A line clipping algorithm against circular window based on intercepts

作　　者：任洪海[1] 郭发军[1] 王艳娟[1] 

机构地区：[1]大连交通大学软件学院数字媒体教研室,辽宁大连116052

出　　处：《图学学报》2012年第5期51-56,共6页Journal of Graphics

摘　　要：在圆形窗口圆心为坐标原点的前提下,确定两端点同时在外切正方形某边界之外或至少有一端点在圆形窗口之内的线段之后,当线段两端点都在圆形窗口之外时:如果线段所在直线在x或y任意坐标轴上截距的绝对值小于或等于圆半径r,则可快速判断线段与圆形窗口是否相交;否则,再根据点-线位置关系以及所引切线与线段分别相交外切正方形边的交点坐标相比较判断线段与圆形窗口是否相交。该方法可以加快线段与圆形窗口的求交进程,避免复杂的辅助操作,显著提高裁剪效率。Based on the premise that the center of circle is the coordinate origin, when the two endpoints of a line segment are outside circular window after the line segment that both endpoints are outside any boundary of circumscribed-square or at least one endpoint is inside circular window is determined： if the absolute value of the intercept on x coordinate axis or y coordinate axis is less than or equal to radius r, the intersection can be identified quickly; otherwise, the intersection is identified according to point-line relation and comparison of coordinates of intersections when the tangent and the line segment separately cross the edge of circumscribed-square. The new algorithm can quickly calculate the intersections between a line segment and circular window, avoid the complicated auxiliary operation and further improve the clipping efficiency.

关 键 词：计算机应用 圆形窗口线裁剪 截距 外切正方形 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]