参数化CAD系统中实现椭圆（弧）功能的算法研究

针对目前参数化ＣＡＤ系统中无椭圆（弧）功能的问题，提供了绘制和拾取任意位置椭圆（弧）和剖面线的算法。在绘制椭圆（弧）时，算法能自动产生决定其特征参数的前趋，由此绘制的椭圆（弧）同其它图形实体一样可以进行各种编辑和尺寸驱动，实现参数化设计。该算法已应用于开发基于作图辅助线和辅助国的参数化ＣＡＤ系统中。

RESEARCH ON ALGRITHMS OF REALIZING ELLIPSE AND ELLIPTIC ARC FUNCTIONS IN PARAMETRIC CAD SYSTEM

This paper presents some algrithms of drawing and picking a general ellipse and elliptic arc as well as its hatch. When drawing them,the algrithms can automatically produce the predecessors deciding its feature parametres. the ellipse and elliptic arc drawed in this way may be edited and dimension-driven like other entities. the algrithms have been applied in a parametric CAD system based on the constructive line and constructive circle.