Fast animation and control of nonrigid structures

We describe a fast method for creating physically based animation of non-rigid objects. Rapid simulation of non- rigid behavior is based on global deformations. Con- straints are used to connect non-rigid pieces to each other, forming complex models. Constraints also provide mo- tion control, allowing model points to be moved accurately along specified trajectories. The use of deformations that are linear in the state of the system causes the constraint matrices to be constant. Pre-inverting these matrices there- fore yields an enormous benefit in performance, allowing reasonably complex models to be manipulated at interac- tive speed.