HiPhyEngine Material Models

HiPhyEngine supports full coupling of multiple different material models. Picking the right material model for the right phenomenal is crucial to get a stable simulation result that fits your expectation. For Lagrangian simulation, HiPhyEngine supports 6 different material models: Affine Body, Elastic Rod, Cloth, Deformable Body, Kinematic Collider, and Soft Collider.

Affine Body

Affine Body in HiPhyEngine is an implementation of the work by Lan et. al.. It is designed for simulating very stiff objects while holding many advantages over rigid bodies mathematically. For the purpose of the simulation setup, they can be treated as the material models for rigid objects.

Elastic Rod

Elastic Rod in HiPhyEngine is an implementation of the work by Bergou et. al.. Different from a traditional spring-based system, a single elastic rod can resist twist and bend, which makes them ideal for simulation hair (especially curls) and other type of thin threads that have a innate curvy structure that needs to be maintained in simulation.

Cloth

Cloth in HiPhyEngine is an implementation of the work by Baraff et. al. and Macklin et. al.. It can be used to simulate soft fabric materials.

Deformable Bodies

Deformable Body in HiPhyEngine is an implementation of the work by McAdams et. al. and Smith et. al.. It simulates the stable Neo-Hookean material model, with a multigrid solver. It can be used for soft 3D objects like elastic objects, muscles, and soft tissues for volume conservation and create secondary motions.

Kinematic Collider

Kinematic Colliders are standard collision objects. They are directly taken from the animation, the simulator will not deform them.

Soft Collider

With animation, it is extremely difficult to create intersection free input for simulations. Without modifications, those collision objects can lead to failed simulation because there is no intersection free solution. HiPhyEngine not only guarantees but requires (unless collision is turned off) the simulation meshes and colliders to be intersection free. Soft colliders are designed to resolve self intersection in colliders from animation input with minimal changes to the silhouette. In contrast to cloth or deformable body, soft collider has carries no momentum. There is be no secondary motion, volume preservation, only intersection resolution for soft colliders.