Incremental Potential Contact

A contact-simulation algorithm that uses barrier potentials to guarantee objects never interpenetrate, well suited to large soft-body deformation.

IPC was proposed by Minchen Li and colleagues at the University of Pennsylvania, Adobe Research, and NYU, published at SIGGRAPH 2020 (ACM TOG). Traditional physics engines often allow objects to interpenetrate slightly before pushing them apart, which makes interpenetration or numerical blow-up likely once the timestep grows large. IPC instead formulates every implicit timestep as an optimization problem, adding a barrier potential that grows sharply as an object's distance to another approaches zero, combined with a line search that incorporates continuous collision detection, guaranteeing the entire trajectory has no intersections and no mesh elements flip — regardless of material, timestep size, or amount of deformation — and it also supports friction. The cost is heavy computation, running far slower than rigid-body engines like MuJoCo. Later extensions include C-IPC for cloth and rods, a rigid-body version called rigid-ipc, and the IPC Toolkit, which can be embedded in other simulators.

ExampleIn the paper's demonstrations, IPC handled scenes with up to about 498,000 contacts and 2.3 million tetrahedra within a single timestep, remaining interpenetration-free across timesteps ranging from 2×10⁻⁵ seconds to 2 seconds.

Also called

IPC, Barrier-based Contact

Related

Contact Model · Interpenetration · Continuous Collision Detection · Deformable-Body Simulation · Finite Element Method · Cloth Simulation

Sources

Incremental Potential Contact project page
ipc-sim (GitHub organization)