階層の一番上の Transform
( Transform が親を持たない場合は自身を返すことになり、null が返ることはありません。)
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"); } } }