Three-dimensional entity model can visually and completely reflect the geometric and characteristic information of an entity. After research on box girder structure characteristics, on model variables and on modeling process, the paper summarized the modeling rule of box girder structures, put forward the modeling method which is suitable for different kinds of bridge structures, and pointed out the matters needing attention in modeling process. In this paper, with the help of Visual C++and ObjectARX, and by creating the graph entity and regions, the modeling parameters were formed. Furthermore, by using object container of AcDb3dSolid class, the interface functions among stretching, sweeping and lofting were established for the three-dimensional entity of bridge structure, then colors and material or texture were added into the entity. Finally, by means of graphic transformation and Boolean calculation, the three-dimensional entity of bridge structure was assembled integrally, thus the automatic modeling of three-dimensional entity of bridge structure were achieved.%三维实体模型能够直观、完整地反映立体的几何与特征信息。在对结构特征、模型变量与建模过程进行分析的基础上，总结箱梁结构的建模规律，提出适合于不同类型桥梁结构的建模方法及建模中应注意的问题。借助VC++和ObjectARX工具，通过创建图形实体及其面域，形成建模参数，运用AcDb3dSolid类建立的对象容器，建立桥梁结构三维实体的拉伸、扫掠和放样接口函数，并对立体添加颜色或材质。运用图形变换和布尔运算，对三维实体进行整体组装，实现了桥梁结构三维实体自动建模。
展开▼
