Convex Collision-Free Regions

Convex Collision-Free Regions (CCFR) is a new collision-handling approach for deformable simulation that turns non-penetration into an explicit geometric constraint. Instead of inferring feasibility indirectly during solve iterations, CCFR constructs a local convex region for each vertex from surrounding mesh primitive configurations, including edge-edge and vertex-face interactions.

The practical appeal for game and simulation teams is robustness. Because the feasible region is defined before penetration, the method is designed to handle not just primary collisions but also secondary collisions and codimensional contacts, which are common pain points in cloth, hair, wire, and particle setups. The formulation is independent of the contact response model, so it can be paired with different physics behaviors without rewriting the collision logic.

Another notable detail is that CCFR avoids nonlinear optimization entirely. That matters for teams using iterative frameworks such as Extended Position-Based Dynamics, where maintaining strict interior feasibility during updates is not always straightforward. By making the collision constraint explicit and per-vertex, the method is also naturally parallelizable, which should make it attractive for large-scale scenes and dense deformables.

The technique has been demonstrated across cloth, hair, wire, particle systems, and codimensional contact scenarios. For developers, the main takeaway is a potential path toward more stable collision handling with less solver coupling, especially in content-heavy simulations where robustness and...