Improvement Of Cloth Collision And Friction Simulation Algorithm On Position Based Dynamics

Computer animation has always been one of the research focuses of computer graphics,virtual reality and computer vision,and has important application value in the fields of game entertainment,film and television animation,and auxiliary design.Cloth animation is an indispensable part of various animation scenes,and its simulation effect will directly affect the authenticity of the picture.The collision and friction contact behavior of cloth is an important content that affects the realism of cloth simulation.How to deal with the complex collision of cloth interaction in the simulation process has become one of the main bottlenecks in current research.Choosing fast and accurate collision detection and processing can effectively avoid cloth.The appearance of visual artifacts such as cloth penetration.In addition,it is also very important to correctly handle the influence of friction factors on the movement state of the cloth during the collision and contact process,which is also very important for generating realistic cloth animation and expressing various forms of cloth.In order to speed up the speed and accuracy of collision detection in the cloth simulation process to obtain more effective friction processing,a cloth collision and friction processing algorithm based on position dynamics is improved.Firstly,in order to improve the speed and applicability of cloth model construction,the cloth modeling based on position dynamics is improved,and the virtual triangle bending constraint based on distance is introduced,which avoids the calculation of the normal vector of the inverse trigonometric function and the dihedral angle,thereby simplifying Constraint solving process,at the same time,eliminate the application limitations of traditional dihedral angle bending constraints relying on cloth mesh topology,and build a fast cloth model.Secondly,in order to ensure the efficiency of cloth collision detection,a hash function is introduced for uniform space division,reducing the number of collision pairs that need to be detected,thereby speeding up the collision detection speed,and at the same time,According to the neighboring relationship of the mass points,the collision "dangerous set" of the cloth mass points is constructed to solve the problem of low detection accuracy caused by the hash parameter being an integer.Then,in order to improve the stability of cloth simulation and improve the speed of collision constraint calculation,the Jacobi iterative method is used to solve multiple collision constraint equations simultaneously,eliminating the jitter problem that occurs when solving multiple collision conflicts,and speeding up the convergence speed of multiple collision constraints.In addition,Aiming at the problem that the cloth model based on positional dynamics cannot handle static friction and strong friction,define the penetration depth function between the particles,calculate the displacement increment of the cloth particles in the tangent direction,and finally realize the simulation between the cloth and the cloth and other objects The phenomenon of static friction and strong friction between.Finally,a cloth simulation system based on position dynamics is designed and implemented.Through comparison experiments of multiple sets of interactive cloth simulations,the effectiveness of the improved algorithm for cloth collision and friction processing is verified.