快速判别直线段与圆位置关系的算法研究

提出了一种直线段相对于圆形区域位置关系的快速判别方法，该算法首先利用圆心到直线段所在直线的距离以及从圆心向直线段所引的垂直射线，判别直线段与圆的位置关系，在确定直线段与圆有交点的情况下，用旋转矢量法求解交点，该算法引进的主射线、主矢量等概念思路新颖，在判断线段完全可见或完全不可见方面，计算量小，效率很高。

Research on the algorithm for rapid judging position relations between line segments and a circle

A rapid judgment on relative position relations between a line segment and a circle is presented in this paper. The basic principle is to judge the position relation between a line segment and a circle window by means of the distance from the center of the circle to the line on which the line segment lies ,and the distance of perpendicular ray of the line segment from the circle center, when the intersection happens, the intersecting point or points will be obtained. The concept of principal ray and principal vector created in this algorithm is brand new.Computing is in extremely high efficiency when judging complete visibility or invisibility of line segment.