Research Of Real-time Collision Detection Of Cloth Simulation

In graphics field, cloth simulation becomes hotspot in computer graphics. The application refers to many fields such as CAD, virtual surgeon, garment design and so on. Cloth modeling is the base of cloth simulation, choosing appropriate model has great affect on simulation results and efficiency. Collision detection and response is another important problem, so this paper makes discussion and research on cloth simulation and collision detection.First we use mass-spring model to simulate cloth, apply Newton Second Law to analyze and get motivation equation. Via comparison among Euler method, mid-point method, Runge-Kutta method and verlet method, we choose fast and simple verlet method, and experiments show that verlet method is fast and has good stability.Second, when local deformation happens in cloth, this paper puts forward an improved model based on mass-spring model and use the concept "transmitting depth of force" to control the counts of vertex computed. We discuss in three situations according to position of vertex forced: edge vertex forced, inner vertex forced and terminal vertex forced. In different applications we can adjust "transmitting depth of force" to make compromise between speed and accuracy. This model can decrease counts of vertex computed and further decrease computing time on the premise of simulation accuracy. Experiment results make good effects that the system's speed is improved on the premise of simulation accuracy.In order to avoid "super-elasticity" phenomenon during cloth simulation, we introduce two methods: position adjustment and speed adjustment. Because verlet method we use just adjusts vertex's position, so we use position adjustment method to solve the problem.Last, this paper uses AABB bounding volume to deal with collision of cloth. We construct AABB hierarchical bounding volume tree for cloth and other objects, so collision between cloth and objects can be transferred to the traverse and interaction between two trees. When collision happens, update AABB volume from bottom to top. The physics conception of resistance coefficient is used to deal with collision response, of which the reasoning process and the method used to update the real-time system is also proposed. Experiments show this cloth simulation system can satisfy requisitions of precision and real-time modeling.