Physical Simulation Of Absorbent Cloth

With the rapid development of computer hardware and computer graphics technology,the scale of virtual scene is becoming more magnificent.The geometry structure and the mechanical model of 3D objects are increasingly complex.Traditional computer animation technology faces many problems.And at the same time,the user requirements for realistic virtual scene and real-time rendering become more and more strict.The simulation of absorbent cloth is a topic covering a variety of technology including cloth simulation,fluid simulation and collision detection.Modeling the process of porous flow in the cloth with traditional computer animation technology,it is easy to find the unrealistic point for users.In this thesis,a physically based method to simulate the mechanics of a fluid flowing through porous deformable materials is presented.We combine the fluid simulation,fluid simulation and collision detection technology to simulate the absorbent cloth in real world.The main contribution of this thesis can be summarized as follows:(1)We present a constraint based real-time cloth simulation framework.And we implement 2D meth cloth and yarn-based cloth simulation with this framework.After analyzing the mass-spring cloth model,we use position based dynamics to solve the constraint function in our cloth model in our framework.And then,we refer the mechanical structure of woven cloth to simulate the yarn level cloth.It is shown that the algorithm can achieve the real-time cloth simulation with good stability.(2)We present a three-step continuous collision detection system for fluid-cloth coupling.The system can be divided into three steps including broadphase collision detection,midphase collision detection and narrow phase collision detection.After handling the collision pairs,the system will calculate the collision response for them.For reducing the jitter problem,we design a sleep and wake-up process,as well as improving stability and efficiency.(3)We design a physically based method to model the porous materials.And we use this method to achieve the physically based wetting process of porous deformable materials.Law of Darcy is introduced to model the simulated cloth as a porous material and to model the process of capillary action.Inter diffusion and inter diffusion in and between porous materials is introduced.With the help of the above technologies,we integrated this algorithm into meth cloth simulation and yarn-based simulation.Compared with previous work,the rendering results shows we achieve more complex diffusion process and we are time efficient.