期刊名称：Journal of Computing and Information Technology
印刷版ISSN：1330-1136
电子版ISSN：1846-3908
出版年度：1995
卷号：3
期号：4
页码：229-244
语种：English
出版社：SRCE - Sveučilišni računski centar
摘要：A 2D constraint-based geometric modelling system is considered in the paper. Constraints are solved by local propagation of known states. The weakness of local propagation (it cannot solve cyclic constraints) is explained by an example. A biconnected constraint description graph is used to support local propagation. As a result of constraint solving an acyclic constraint description graph is obtained and it can be observed as a parametric description of a geometric object. The acyclic constraint description graph stores the sequence of applying constraints for generation of instances. It is shown that the time complexity of the algorithm for generation of an instance is 0(n2), where n is the number of basic geometrical elements included. In the last part of the paper we demonstrate how geometrical relations among geometrical objects can be established by the introduced geometrical constraints.
关键词：geometric modelling; constraints; local propagation; constraint description graphs
