What does btRigidBody::setCenterOfMassTransform do?

[robagar]

.. and should I use it in place of btCollisionObject::setWorldTransform to reposition an object?

[Flix]

Good question. From the Bullet source code:

Code: Select all

void	btCollisionObject::setWorldTransform(const btTransform& worldTrans)
	{
		m_worldTransform = worldTrans;
	}

Code: Select all

void btRigidBody::setCenterOfMassTransform(const btTransform& xform)
{

	if (isStaticOrKinematicObject())
	{
		m_interpolationWorldTransform = m_worldTransform;
	} else
	{
		m_interpolationWorldTransform = xform;
	}
	m_interpolationLinearVelocity = getLinearVelocity();
	m_interpolationAngularVelocity = getAngularVelocity();
	m_worldTransform = xform;
	updateInertiaTensor();
}

So it seems that the second can handle static and kinematic bodies, interpolated velocities and, for some reasons, updates the inertia tensor too...

[robagar]

these interpolated velocities etc, are they used in continuous collision detection? I'm wondering if the intention is to use this function with btContinuousDynamicsWorld (when it's finished )

[Flix]

these interpolated velocities etc, are they used in continuous collision detection? I'm wondering if the intention is to use this function with btContinuousDynamicsWorld (when it's finished )

I honestly don' know it... Maybe interpolated velocities are just used to calculate interpolated transforms during "interpolated" physic timesteps (when stepSimulation() is called with a delta time < Bullet timestep).