CVS工具包，实现三维实体的碰撞，内有详细的说明

实体的B-rep表示模型是一非常复杂的模型，要求能够表达出多面体各几何元素之间完整的几何和拓扑关系，并且允许对这种几何和拓扑关系进行修改.在B-rep表示中，体、面、边和顶点是最基本的几何元素，在实体的拼合、显示、分析计算或人机交互过程中-The B-rep solid representation model is a very complex model, requires the ability to express the polyhedron between the geometric

两条直线的起始点，终点，四个点，判断有无交点，并说明交点是实点，还是虚点-Two straight lines starting and end points, four points, to determine whether the point of intersection, and that intersection is a solid point, or virtual point