btRayCastVehicle, slight lateral slip on slopes when still

[Skuzz]

On a slope with brakes on, no engine force (i.e, parked) my vehicle creeps *laterally only*, tweaking various suspension settings in realtime doesn't help, too much frictionSlip causes jittering, and doesn't help anyway.

Happens with or without btMotionState usage.

Feels like something fundamental.

Any ideas?

[Skuzz]

btContactConstraint.cpp

Changing contactDamping to 1.0 improves things:

Code: Select all

	//todo: move this into proper structure
	btScalar contactDamping = btScalar(0.2);

...

	btScalar velocityImpulse = -contactDamping * rel_vel * jacDiagABInv;
	impulse = velocityImpulse;

impulse is 'm_sideImpulse', which back in btRayCastVehicle.cpp has another random stiffness var applied to it:

Although sideFrictionStiffness2 is set to 1.0 by default.

Code: Select all

m_sideImpulse[i] *= sideFrictionStiffness2;