Version: 2020.2
public Transform root ;


Returns the topmost transform in the hierarchy.

(This never returns null, if this Transform doesn't have a parent it returns itself.)

using UnityEngine;

public class Example : MonoBehaviour { // Is a collision between two objects with different roots? void OnCollisionEnter(Collision collision) { if (collision.transform.root != transform.root) { print("The colliding objects are not in the same hierarchy"); } } }