Title: Mil2: Efficient Cloth Simulation Using Non-distance Barriers and Subspace Reuse

Abstract: Mil2 pushes the performance of high-resolution cloth simulation, making the simulation interactive (in milliseconds) for models with one million degrees of freedom (DOFs) while keeping every triangle untangled. The guarantee of being penetration-free is inspired by the interior-point method, which converts the inequality constraints to barrier potentials. Nevertheless, we propose a major overhaul of this modality by defining a novel and simple barrier formulation which does not depend on the distance between mesh primitives. Such a non-distance barrier model allows a new way to integrate collision detection into the simulation pipeline. Another contributor to the performance boost comes from the so-called subspace reuse strategy. This is based on the observation that low-frequency strain vibrations are near orthogonal to the deformation induced by collisions or self-collisions, often of high frequency. Subspace reuse then takes care of low-frequency residuals, while high-frequency residuals can also be effectively smoothed by GPU-based iterative solvers. We show that our method outperforms existing fast cloth simulators by nearly one order while keeping the entire simulation penetration-free and producing high-equality animations of high-resolution models.