Implicit Constraint Enforcement for Stable and Effective Control of Cloth Behavior

Stable and effective enforcement of hard constraints is one of the crucial components in controlling physicsbased dynamic system. This paper presents a new implicit constraint enforcement technique that is stable over large time steps and does not require problem dependent adhoc parameters. The conventional explicit Baumgarte constraint stabilization confines the time step to be within a stability limit and requires users to pick problemdependent coefficients to achieve fast convergence or to prevent oscillations. Although Post-stabilization method provides more accurate constraint enforcement, it requires additional computation burden to correct numerical drift. Proposed implicit constraint enforcement method uses the future time step to estimate the correct magnitude of the constraint forces, resulting in better stability over bigger time steps. In addition, its asymptotic computational complexity is same as the explicit Baumgarte method. Combined with an adaptive constraint activation scheme, the implicit constraint method demonstrates a substantial enhancement of the controllability of cloth simulation.