Spring - Mass Model-based Cloth Simulation

In the past decades, cloth simulation has become more and more important in research areas of computer graphics. Due to rapid development of computer technology, today's cloth simulation can simulate cloth deformation through computer animation. But the technology still can not meet the demands of our information age. With the rapid development of the Internet, e-commerce, on-line shopping and on-line games have put great demands on realistic and real time cloth simulation. Thus there is still a lot of research work to be done in this area.The goal of this thesis is to develop a stable cloth simulation method that can also meet real time requirement. To achieve this goal, the physical and mechanical properties of real cloth were analyzed and several cloth simulation methods were compared. Method based on mass-spring model was chosen. Dynamics equations of cloth simulation were established based on Newtonian mechanics. These equations were solved using explicit-Euler integration method for its fast computation speed. More complex time integration method such as Runge-Kutta method was also tested.Another important part of cloth simulation is how to deal with collision between the cloth and other rigid objects. To achieve real time effect, a simple and efficient collision detection method based on specific rigid objects was developed. Bisection method and penalty force method was used for their efficiency. Air resistance to the mass points was introduced to reduce the inertia effects of the penalty force. The air resistance model achieved good effects in stabilizing the cloth model.The simulation program was developed using Microsoft Visual C++6.0. OpenGL was used for 3D scene rendering and animation. The program can simulate the entire process of cloth descending and colliding with a sphere or a table. Real time realistic cloth deformation and collision response was achieved.