Air meshes for robust collision handling

Figure 1: A dancer with a multi-layered skirt. Our method robustly simulates the complex interaction of the layers and is able to smoothly recover from any entangled state. We propose a new method for both collision detection and collision response geared towards handling complex deformable objects in close contact. Our method does not miss collision events between time steps and solves the challenging problem of untangling auto-matically and robustly. It is conceptually simple and straight for-ward to parallelize due to the regularity of the algorithm. The main idea is to tessellate the air between objects once before the simulation and by considering one unilateral constraint per element that prevents its inversion during the simulation. If large relative ro-tations and translations are present in the simulation, an additional dynamic mesh optimization step is needed to prevent mesh lock-ing. This step is fast in 2D and allows the simulation of arbitrary scenes. Because mesh optimization is expensive in 3D, however, the method is best suited for the subclass of 3D scenarios in which relative motions are limited. This subclass contains two important problems, namely the simulation of multi-layered clothing and tis-sue on animated characters