二维工程图形中相切关系分析及计算机编码方法

相切约束从位置关系上来说是一种较复杂的约束，多数相切约束存在多解情况，从多解中确定出和原来图形相符的解是图形参数化系统能否正确进行尺寸驱动的关键。为此，在深入研究二维工程图形中常见相切位置关系的基础上，结合矢量叉积的概念，给出了一种确定图元相切位置关系的方法。

The Analyzing and Computer Recognizing the Tangent Relations Between 2 Objects in 2D Drawings

Tangent relation is one kind of complicated constraints. Multiple solutions exist in most questions on tangent constraint. In 2D drawing parametric system, obtaining the solution matched with original drawing is the key point for modifying drawings correctly. Therefore, several kinds of tangent relations are studied. A new method used for confirming tangent relations among different drawing elements is presented. By using this method the tangent relations can be recognized by computer.