Some subtle problems about conveyor using contact callback and special friction mode

[Winson]

Hello,

I'm try to use contact callback and special friction mode, with a target velocity and direction to simulate a conveyor.
Like this topic about "How to simulate a conveyor?": viewtopic.php?f=9&t=6076

The following is my conveyor (Static RigidBody):

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btRigidBody* conveyor = createRigidBody(mass(0), transform, shape, color);
conveyor->setCollisionFlags(btCollisionObject::CF_KINEMATIC_OBJECT);
conveyor->setUserIndex3(10086);
conveyor->setCollisionFlags(conveyor->getCollisionFlags() | btCollisionObject::CF_CUSTOM_MATERIAL_CALLBACK);
conveyor->setFriction(0.5);

I judge the collision between box and conveyor by UserIndex3 in ContactAddedCallback or ContactProcessedCallback.

Here is myContactAddedCallback

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bool myContactAddedCallback(btManifoldPoint& cp, const btCollisionObjectWrapper* colObj0Wrap, int partId0, int index0, const btCollisionObjectWrapper* colObj1Wrap, int partId1, int index1)
{
	//cp.m_contactPointFlags |= BT_CONTACT_FLAG_FRICTION_ANCHOR;
	cp.m_contactPointFlags |= BT_CONTACT_FLAG_LATERAL_FRICTION_INITIALIZED;
	if (colObj0Wrap->getCollisionObject()->getUserIndex3() == 10086 
		|| colObj1Wrap->getCollisionObject()->getUserIndex3() == 10086)
	{
		const btCollisionObjectWrapper* target = colObj0Wrap->getCollisionObject()->getUserIndex3() == 10086 ?
			colObj0Wrap : colObj1Wrap;
		btVector3 v(-1.f, 0, 0);
		btTransform s = colObj0Wrap->getWorldTransform();
		v = v.dot3(s.getBasis().getRow(0), s.getBasis().getRow(1), s.getBasis().getRow(2));
		cp.m_lateralFrictionDir1 = v;
		cp.m_contactMotion1 = 1;
	}
	return true;
}

The situations as follows is reasonable.

1.

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conveyor->setFriction(0.5); & cp.m_contactMotion1 = 0.8;

2.

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conveyor->setFriction(0.2); & cp.m_contactMotion1 = 0.8;

That seems workable, but has some subtle problems: The box will come to rest after traveling a certain distance.

3. When cp.m_contactMotion1 is a little bit small and friction is greater than the horizontal component of gravity:

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conveyor->setFriction(0.5); & cp.m_contactMotion1 = 0.6;

4. When conveyor's friction is a little bit smaller (the horizontal component of gravity is greater than friction) :

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conveyor->setFriction(0.3); & cp.m_contactMotion1 = 0.6;

I think both of these cases are because myContactAddedCallback() is not called.
What causes it?

After the box stopped, the left mouse button click on the box, the box will move again and come to rest after traveling a certain distance.

Thanks!

See attached BasicExample.cpp

BasicExample.cpp

(11.31 KiB) Downloaded 204 times

[Winson]

This example's description as follows:

Press W for wireframe.
Press D to toggle auto-deactivation of the simulation.

I try to press "W" to show wireframe. I found it works that the box can move normally.
When the box stopped, I try to press "D" to activate the box again, but it didn't work.
However, I try to press "W" and then "D" that I found it works.

Does anyone know where to view the keyboardCallback method about this part?