OSG-Based Realtime Cloth Simulation

Realtime simulation of cloth is one of the most fascinating areas of computer animation. During the past decades, a considerable amount of research has been carried out by mathematicians, physicians and engineers. Although much research has already been done, fast and realtime cloth simulation still remains a challenge.This thesis introduces the process of cloth simulation, which is base on the physical model, including building model, controlling movement, and collision detection and resolution. To improve the efficiency of collision detection, the author proposes a Quad-tree based method for collision detection.First, this thesis introduces the mass-spring model and other models of cloth simulation, and analyses the advantages and disadvantages of each model. The author proposes an improved mass-spring model which is based on the classic ones. Using the classic Newtonian mechanics model and law of motion, the author analyses the situation of the model, introduces a perturbational force to improve the model's flexibility, and gives the composition and expression of internal and external cloth forces in formulation.Then, the thesis analyses the method of collision detection and response, which is a critical technology of the realtime simulation of cloth, gives the general framework and some typical methods of collision problem and proposes a hierarchical Quad-tree based collision detection method. The collision detection of realtime simulation of cloth includes external-collision and self-collision detection. To deduce the complexity of external-collision, the author creates a hierarchical Quad-tree, which is used for deducing the complexity of collision computation. To the self-collision detection, the curvature of triangles surface method is introduced.Finally, the thesis introduces a new open source, cross-platform graphics toolkit, names OpenSceneGraph(OSG), gives the processes of the realtime simulation of cloth, and carries it out in OSG environment. To lay out the effect of the method, the author gives some examples, which is executed in this system.Results demonstrate that the realtime simulation of cloth system can simulate the movement and situation of cloth, and resolve the distortion phenomenon by deducing the rigidity of springs. And the improved model can get good results both in efficiency and sense of reality.