Bringing rigid bodies to "life"

Physics-based animation employs the laws of physics to animate mechanical and geometrical objects on computers. Essentially, this animation technique incorporates various physical parameters, as well as geometrical information, into a computer model of the object, then applies well-known laws to the model, thereby simulating the object´s behavior under various stresses and forces. We have used physics-based animation to study the behavior of three rigid bodies: a spring; a spider web; and a polyhedron. We describe each of these animations in this article, with special emphasis on the polyhedron.