Unified Simulation of Rigid and Flexible Bodies Using Position Based Dynamics

Abstract

In this paper we present a new position based approach for simulating rigid and flexible bodies with two-way coupling. This is achieved by expressing all the dynamics as constraints and running them in the same solver. Our main contribution is an accurate contact and Coulomb friction model based on a fixed point iteration of a cone complementarity problem. We formulate the problem as a nonlinear convex minimization at position level and solve it using a new accelerated form of projected Jacobi. We add elasticity to the constraints by means of regularization and show how to add more damping in a credible manner. We also use this viscoelastic model to build an accurate position-based finite element solver for soft bodies. The novelty of this solver is that it is no longer an approximation and it is based directly on the elasticity theory of continuous media.