一种针对非均匀有理B样条曲面的碰撞检测算法

提出了一种针对非均匀有理B样条（NURBS）曲面的碰撞检测算法，它将节点反插技术引入到NURBS曲面细分中，通过控制点间距离测试进行精确碰撞检测．该算法首先插入几何意义较为清楚的控制顶点，反算出要插入的节点，再采用节点插入技术将曲面细分，然后为逐步细分的曲面控制点建立固定方向凸包（FDH）包围盒，以尽早排除不可能碰撞的情况．在到达一定细分层次后，进行曲面之间的距离测试，若距离小于某一阈值，则认为发生碰撞．通过虚拟环境中蝴蝶与玉米叶的碰撞实验表明，所提算法可以应用于由NURBS曲面表示的物体碰撞检测，在细分层次为5，阈值为0．0006时，可以使本例碰撞检测具有良好的精确性和实时性。

Collision Detection Algorithm for Non Uniform Rational B-Spline Surface

A collision detection algorithm for NURBS(non uniform rational B-spline) surface is proposed.The technique of inserting node in reverse is used in NURBS surface subdivision,and a method for the accurate collision detection using distance testing between control points is presented.In the algorithm,firstly,the top control points that have clear geometric meaning are inserted,then the inserted nodes are calculated in reverse,and the insert technique is used to divide the curved surfaces finely;secondly, through building FDH(fixed direction hull) for the control points of curved surfaces that are finely divided by degrees,the part that is impossible to join in collision can be excluded early;finally,the distance testing is carried out if the subdivision level reaches a certain threshold.Through the collision detection between a butterfly and corn leaves in the virtual environment,it is verified that this algorithm can be used for collision detection between objects defined by NURBS surfaces.When the subdivision level is 5 and the threshold is 0.000 6,the collision detection in this experiment is real-time with good accuracy.