Interactive control of linked rigid body simulations

Abstract

Numerical simulation of linked rigid-body motion generates realistic motion automatically. Simulation alone, however, prevents intuitive direction. In the worst case, an artist repeatedly tweaks a variety of simulation parameters until she achieves the desired effect. Because of the complexity of the dynamics of linked rigid bodies, the tweaking becomes tedious, even for the simplest animation goals. This thesis describes an interactive technique for direct control of linked rigid-body simulation with a click-and-drag interface. It uses numerical simulation to preserve the physical realism of the motion. Differential control, an interactive form of gradient descent, provides the basis of the interface. This thesis extends differential control to edit the motion of linked rigid bodies connected with passive joints in an open-loop topology. The linked object can collide for an instantaneous or sustained time period at a single point of contact.