An interactive 3D modeling system is studied and implemented,which takes the boundary representation method to represent the 3D model as the theoretical foundation. An improved half?edge data structure is proposed to represent the 3D model,and various forms are generated by means of Euler operator. The model cutting,Boolean operation of the entity intersec?tion difference,and calculation of the entity volume and superficial area were realized in the system. The 3D model rendering was realized by means of the fusion of OpenGL or Direct3D library function with the improved half?edge structure of the system. The voxelization algorithm of the 3D entity was implemented in the simulation module,by which the octree?based 3D space seg?mentation method combining the regular tetrahedron with cuboid is used to segment the entity space to calculate the center of gravity of the object. A simulation example of the thread milling was realized with this system.%研究并实现了一个交互式的三维建模系统，该系统以边界表示法表达三维模型为理论基础，同时提出一种改进的半边数据结构来表达三维模型，通过欧拉算子生成各种形体。系统实现了模型切割、实体交并差的布尔运算，以及对实体的体积、表面积的计算。在场景渲染方面，利用OpenGL或者Direct3D的库函数结合系统所采用改进的半边数据结构实现了3D模型的渲染。在仿真模块实现了三维实体的体素化算法，该算法采用正四面体和长方体相结合的八叉树三维空间分割法对实体进行空间分割，实现了对物体重心的计算，最后用该系统实现了一个螺纹铣削加工的仿真实例。
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