Two box colliders not causing OnCollisionEnter to fire?

Unity Engine
,
1

Maybe I’m missing something dumb but I have two box colliders, on two different layers.

I have the following code attahced to one of the gameobjects that contains a box collider, but this method never fires when the two colliders interact.

void OnCollisionEnter(Collision col) {
  // Code here for collision, but this method never fires
}

1.) I have checked the collision matrix, both layers are set to collide with each other
2.) One of the colliders has a rigidbody attached
3.) The colliders are not set to be triggers.
4.) I’ve tried modifying the layer overrides, no difference.

Am I missing something?

I can only ever get it to fire with OnTriggerEnter, by marking my one object as a trigger. But otherwise can never get OnCollisionEnter to fire.

Thanks

2
  1. neither collider is an ancestor of the other,
  2. the rigidbody is dynamic, isKinematic=false,
  3. the behaviour expecting OnCollisionEnter is on the same object as the rigidbody,
  4. the rigidbody’s motion is only via physics, e.g., MovePosition or velocity or AddForce
1 Like
3

Thanks, I’m guessing #7 is where I’ve got it wrong…

My OnCollisionEnter is not on the same gameObject as the rigidbody, the rigidbody is on the other object that receives the force of the collision.

4

The script that handles OnCollisionEnter doesn’t need to be on the rigidbody.

5

It does, I’ve just fixed the issue by moving the script onto the gameObject that has the rigidbody component.

6

Strange… I wonder if they’ve changed something in later versions. In version 2021.3 I don’t need to have a script present on the rigidbody.

7

Possibly, that’s why I was so confused lol

8

You can have the script on the collider that has the dynamic Rigidbody as an ancestor, but putting a script on a non-Rigidbody-backed collider is not going to reliably be informed of collisions.