基于几何关系的椭圆图形生成算法  

An Ellipse-Generation Algorithm Based on Geometric Relations

作　　者：陈震岳[1] 朱桂林[1] 

机构地区：[1]浙江大学计算机学院,浙江杭州310027

出　　处：《计算机工程与科学》2004年第8期56-59,共4页Computer Engineering & Science

摘　　要：在常规CAD图形生成算法中,往往只考虑图形的坐标方程(包括直角坐标方程、参数方程或极坐标方程),却忽略了图形本身所具有的特点或一种图形与另一种图形之间的几何关系,而有时这种几何关系可以简化图形生成算法。本文提出了一种新的椭圆生成算法,利用椭圆与其外接圆和内切圆之间的相互位置关系,通过先生成两个圆来生成一个椭圆。在该算法的主循环中,只有加、减法和移位运算,以此替代了速度慢的乘、开方等运算,从而降低了计算量。Traditional CAD graphics-generation algorithms usually take the coordinate equations(including rectangular coordinate,parameter or polar coordinate equations)into consideration,but ignores the characteristics in graphics and the geometric relations between them.And sometimes these relations can simplify the graphics-generation algorithm.This paper proposes a new ellipse-generation algorithm based on geometric relations.It makes use of the geometric relations between an ellipse and its circumcircle and inscribed circle.In the main loop of this algorithm,there are only addition,subtraction and shift operations instead of multiplication and square-root operations.So the calculation cost and errors are reduced.

关 键 词：CAD 几何关系 椭圆图形生成算法 坐标方程 图形特征 

分 类 号：TP391.72[自动化与计算机技术—计算机应用技术]