PxMaterialFlag

Defined in include/PxMaterial.h

struct PxMaterialFlag

Flags which control the behavior of a material.

See also

PxMaterial

Public Types

enum Enum

Values:

enumerator eDISABLE_FRICTION: If this flag is set, friction computations are always skipped between shapes with this material and any other shape.

enumerator eDISABLE_STRONG_FRICTION

Whether to use strong friction.

The difference between “normal” and “strong” friction is that the strong friction feature remembers the “friction error” between simulation steps. The friction is a force trying to hold objects in place (or slow them down) and this is handled in the solver. But since the solver is only an approximation, the result of the friction calculation can include a small “error” - e.g. a box resting on a slope should not move at all if the static friction is in action, but could slowly glide down the slope because of a small friction error in each simulation step. The strong friction counter-acts this by remembering the small error and taking it to account during the next simulation step.

However, in some cases the strong friction could cause problems, and this is why it is possible to disable the strong friction feature by setting this flag. One example is raycast vehicles that are sliding fast across the surface, but still need a precise steering behavior. It may be a good idea to reenable the strong friction when objects are coming to a rest, to prevent them from slowly creeping down inclines.

Note: This flag only has an effect if the PxMaterialFlag::eDISABLE_FRICTION bit is 0.

enumerator eIMPROVED_PATCH_FRICTION

Whether to correct the friction force applied by the patch friction model to better match analytical models.

This flag only has an effect if the PxFrictionType::ePATCH friction model is used.

When using the patch friction model, up to two friction anchors are generated per patch. The normal force of all contacts in the patch is accumulated and equally distributed among the anchors in order to compute friction forces. If this flag is disabled, the legacy behavior is active which produces double the expected friction force in the case of two anchors, since the full accumulated normal force is used in both anchors for the friction computation.

enumerator eCOMPLIANT_CONTACT

This flag has the effect of enabling an implicit spring model for the normal force computation.