Purpose of PxSolverConstraintDesc::constraint

[zopsicle]

Is PxSolverConstraintDesc::constraint supposed to be a generic userdata field? SnippedImmediateMode uses it as such (AFAICT the snippet’s ContactPair type is not something PhysX cares about and is only used in the snippet code):

PhysX/physx/snippets/snippetimmediatemode/SnippetImmediateMode.cpp

Lines 788 to 791 in 561a0df

	//Cache pointer to our contact data structure and identify which type of constraint this is. We'll need this later after batching.
	//If we choose not to perform batching and instead just create a single header per-pair, then this would not be necessary because
	//the constraintDescs would not have been reordered
	desc.constraint = reinterpret_cast<PxU8*>(&pair);

However, the field is also read by PhysX itself by PxCreateContactConstraintsTGS:

PhysX/physx/source/immediatemode/src/NpImmediateMode.cpp

Line 649 in 561a0df

PxU8 type = *contactDescs[currentContactDescIdx].desc->constraint;

Should I set it to null before calling PxCreateContactConstraintsTGS?

[zopsicle]

Apparently the field is overwritten by the call to Dy::createFinalizeSolverContactsStep inside PxCreateContactConstraintsTGS, so I don’t have to set it to null first. So it’s safe to use it as a generic userdata field before the call to PxCreateContactConstraintsTGS.