Cloth test video

This is a low resolution version of a cloth simulation that I wrote for Physically Based Animation.  It uses Position Based Dynamics, which is a relatively new method for this kind of thing.  I really like this method, especially the mathematics behind it.  The method represents the cloth as a series of constraint functions.  There are constraints for stretching, bending, pressure, and collisions.  PBD basically uses Euler integration to find predicted positions for every vertex on the cloth.  Then it checks these predicted positions to see if they violate any of the constraint functions.  If they do, you correct the predicted positions and go to the next time step.