Cloth Simulation Based On Mass-Spring Model

How to effectively and realistically simulate movements, wrinkles and other phenomena related to cloth has always been one of challenging topics in computer graphics research since 1980's. Cloth simulation can be widely applied to 3D digital garment construction, Virtual Reality technique, movie entertainment, computer games and many other areas.Physically-based simulation models have gradually become dominant methods owing to its lifelike result, one of which is Mass-Spring Model. It is even more prevalent adopted not only because of its simplicity, easiness to use and implement, but also its high computational efficiency. So it is also chosen by this paper. After accomplishing model forces analyses, Explicit Integration is implemented to calculate positions and velocities of all particles in the next time step. This experiment achieves very excellent simulation effect, and can reach real-time rendering in the case of less particles. In order to prevent the"Super-Elastic"and movement dithering effect, deformation constraints are employed.As one of crucial aspects, integration methods have significant importance to the simulation effect, stability and speed. Based on thorough introductions and comparisons of common integration methods, this paper gives detailed analyses of three representative methods: Explicit Integration, Implicit Integration and Semi-Implicit Integration. Some experiments are carried out about them. Above all, their simulation effects are contrasted; it also amends deformation effect of implicit method and diminishes dithering effect of Semi-Implicit method by reasonably adjusting experimental parameters. The initialization of each method is just to set default values for variables and matrices used in the calculation. Then, Experimental data show that initialization speed of Semi-Implicit Integration is the lowest, while explicit the highest. FPS (Frames Per Second) is related to running speed. By depicting curves of these three methods'FPS values corresponding to the number of particles, Explicit Integration gets the highest running speed, while implicit the lowest. In spite of that, Implicit Integration has the best simulation stability.Collision detection and collision response are bottlenecks and research focuses of cloth simulation. Based on concluding general collision framework, this paper firstly summarizes and classifies common collision detection speed-up algorithms, and points out the characteristic of cloth simulation: self-collision and its usual response techniques. Then, basic geometric elements comparison comes down to"point-triangle"and"edge-edge"intersection test by constructing cloth and other objects in the scene using triangle mesh. Collision response method is also analyzed subsequently. Finally, for the collision effect of cloth with ground, this paper adaptively simplifies the general collision detection and response algorithm, thus makes a smooth, nature-like experimental result.