Understanding physics callbacks with non-convex MeshColliders

Unity Engine
1

I just realized that MeshColliders (with convex = off) are not discovered by any of the Physics functions if the collider you use to check against the MeshCollider is completely inside of it.

In clearer terms: all physics functions like SphereOverlap(), OnTriggerEnter(), OnTriggerStay() will only report an overlap if the collider is currently touching of the MeshCollider. If the collider is inside the meshcollider and it doesn’t touch the faces of the meshcollider, then it’s considered out of the mesh and OnTriggerExit() is called.

What do people use to know if an object is within a MeshCollider that’s not convex?

2

Does no one know about this?

3

If one collider is completely inside another collider, then there are no intersection and no event will be fired from physics. This applies to any type of colliders. Collision is detected only when colliders have intersection.