What's going on with the inertiaTensor and inertiaTensorRotation?

Unity Engine
1

I have a RigidBody, not a fancy one, very simple. I must set manually the center of mass to this RigidBody. Doing so it looks like I trigger two bugs in Unity:

first one: as far as I understood, once I set the center of mass manually, Unity should stop recompute it if I change the RigidBody colliders, this instead does not happen, Unity changes the center of mass, forcing me to recompute it again.

second one: after I set new colliders in the rigidbody, the inertiaTensor and inertiaTensorRotation go completely mental. I am forced to remember the old values to still have a good simulation.

Example:

Vector3 inertia = rbTransform.rigidbody.inertiaTensor;
		Quaternion rotation = rbTransform.rigidbody.inertiaTensorRotation;

                //inertiaTensor here is 17.8, 16.4, 4.8

		for (int i = 0; i < colliderCount; ++i) 
		{ //allColliders contains gameObjects with only one BoxCollider component
			Transform collider = allColliders[i];
			
			if (collider.parent != rbTransform)
				collider.parent = rbTransform;
			
			collider.localRotation = Quaternion.identity;
			collider.localPosition = collider.position;	
			collider.gameObject.SetActive(true); //set active must stay after the parenting!
		}

               //new inertiaTensor is now: 11491.2, 11492.6, 2.7

		rbTransform.rigidbody.inertiaTensor = inertia;  //I am forced to do this
		rbTransform.rigidbody.inertiaTensorRotation = rotation; // and this

any clue?

2

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