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 use the patch friction model.

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

When using the patch friction model, up to 2 friction anchors are generated per patch. As the number of friction anchors can be smaller than the number of contacts, the normal force is accumulated over all contacts and used to compute friction for all anchors. Where there are more than 2 anchors, this can produce frictional behavior that is too strong (approximately 2x as strong as analytical models suggest).

This flag causes the normal force to be distributed between the friction anchors such that the total amount of friction applied does not exceed the analytical results.

enumerator eCOMPLIANT_CONTACT

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