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    基于Catmull-Clark细分的曲面布尔运算基础研究

    Basic Boolean Operation Research in Catmull-Clark Subdivision Surface

    • 摘要: 基于Catmull-Clark细分,提出一种对平面四边型网格进行操作的基础布尔运算,包括曲面求交、裁剪和网格级基础布尔运算.首先将细分曲面的求交转换为对一定细分层次的细分控制网格求交,得到满足一定精度要求的交线;采用局部修改交点处的控制网格拓扑结构和控制网格顶点位置的方法,实现了对细分曲面的裁剪;最后提出一种对一定细分层次的四边形控制网格进行操作的布尔运算,称之为细分曲面网格级布尔运算,包括布尔交、布尔并和布尔差3种运算,并给出了运算的基本原则与应用实例.

       

      Abstract: The Boolean operation is the most complex and important problem in CAD/CAM, and the quadrangle is applied in CAD/CAM engineering widely. Being without global analytic representation, the research on subdivision surface Boolean operation is more difficult than that of the parameter surface and implicit surfaces. A kind of basic Boolean operation for plane quadrangle mesh including surface intersection, trimming and gridding-level Boolean operation in the Catmull-Clark subdivision surface is presented in this paper. In the first place, the calculation of subdivision surface intersection is converted into that of control mesh intersection: the 1-neighborhood zone of intersecting quadrangle mesh on the control mesh is constructed, and then the 1-neighborhood zone is subdivided continuously to improve the precision of intersection. The intersection points between the intersection quadrangle are calculated, which are linked according to their topology relation, so the intersection line which satisfies the given precision is calculated. When the subdivision surface intersection is finished, the surface trimming will be realized by modifying the topology structure and vertices positions of control mesh at those intersection points. Finally, a kind of the subdivision surface gridding-level Boolean operation including intersection, union and difference operation is proposed, and the basic principles and application instances are given as well.

       

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