Abstract: In current semantic feature modeling systems，support for the direct manipulation of features is not commonly available，this is due to the lack of speed of current constraint solvers.In this paper，the algorithm of constraint operation and the algorithm of feature operation are presented by making use of the data model of feature dependency graph to preserve feature information and relations among all features，the algorithms confine feature operation to the specific region of model.The method optimally reduces the number of constraints to be solved，meets the requirements of speed of constraint solving in the feature direct manipulation process，achieves the direct manipulation of features.

Key words: semantic feature modeling, constraint solving, direct manipulation, feature dependency graph

摘要： 目前的语义特征造型系统，由于约束求解的速度比较缓慢，还不能支持直接操作的特性。利用特征依赖图的数据模型来保存和维护特征的信息及其之间的依赖关系，并且提出了约束操作算法和特征操作算法，将特征的操作局限在模型的特定区域内。该方法最大限度地减少了所需要求解的约束数目，满足了直接操作过程中对约束求解速度的要求，从而实现了对特征的直接操作。

关键词: 语义特征造型, 约束求解, 直接操作, 特征依赖图