基于交点参数的任意多边形窗口对圆裁剪

Circle Clipping by Arbitrary Polygon Window Based on Intersection Point Parametric Method

现有的任意多边形窗口的圆裁剪算法存在算法繁琐等问题,且没有考虑多边形是带内环的情况,本文提出了一种基于交点参数分析的多边形窗口的圆裁剪算法,只需对多边形边与圆的交点在边所在直线的参数值进行比较,即可判断出交点的进出点特性,交点排序后,通过进点出点组合,即可获得裁剪窗口内的圆弧,完成裁剪.编程实践的实例结果也证明本算法是切实可行的,本文的方法既适用于仅有外环的一般多边形裁剪窗口,也适用于带内环的任意多边形裁剪窗口的圆裁剪,因此,算法更具有通用性.

The existing algorithms of circle clipping against an arbitrary polygon window suffers from complex steps and do not consider the case where the polygon contains an inner ring.Thus,this study presents a new algorithm based on the parameter analysis of intersection points for circle clipping against an arbitrary polygon window.In this algorithm,only by comparing the parameter values of the intersection points on the directional line of the edge,one can classify the intersection points into entry points and exit points.After the intersection points are sorted out,the arcs within the clipping window can be obtained with the combinations of“entry point exit point.”The proposed algorithm is proved feasible by programming results and is universal to circle clipping against an arbitrary polygon window,even if the polygon contains an inner ring.