支持协同CAD的拓扑实体永久命名机制

在特征参数化定义域直接引用B-Rep域中的拓扑实体是以往永久命名方法固有的缺陷。提出了基于特征的解决方案：为特征面建立统一的命名方法，并规定在建模过程中特征面的名字不变；建立拓扑实体与特征面之间的表达关系，在特征参数化定义过程中引用由特征面表达的拓扑面，解决基于特征的协同CAD中拓扑实体永久命名问题；给出提出参考面的概念，用于解决拓扑面、拓扑边分裂和多重交线等问题引起的引用模糊问题。在此基础上，详细讨论了拓扑面、拓扑边匹配的方法。

Mechanism of persistent naming topological entity supporting collaborative CAD

Direct referring to topological entity of B-Rep domain in feature's parametric definition domain is inherent limitation of previous persistent naming topological entity method. Therefore, a feature-based solution for topological entity naming was proposed. Firstly, uniform naming method for feature face was established and its name remained invariable during the modeling procedure. Secondly, the expression between topological entity and feature face was established and topological entity expressed by feature face was referred to during the course of feature's parametric definition, and as a result, the problem of persistent naming topological entity for feature-based collaborative CAD was solved. Thirdly, the concept of reference face was proposed and utilized to solve ambiguous referring problem, which arose from topological face splitting, topological edge splitting and multiply intersection edges. Based on the above mentioned, topological face and topological edge matching method was discussed in detail.