오브젝트 재질 접근 = MeshRenderer
Collision 충돌 정보 클래스
void OnCollisionEnter(Collision Collision) { }
충돌 시작
void OnCollisionExit(Collision Collison) { }
충돌 끝
void OnCollisionStay(Collision, Collison) {}
충돌 중
void OnTriggerEnter(collider other) { }
void OnTirrgerStay(collider other) { }
void OnTriggerExit(Collider other) { } 
public class otherball : MonoBehaviour
{
    // Start is called before the first frame update
    MeshRenderer mesh;
    Material mat;
    void Start()
    {
        mesh = GetComponent<MeshRenderer>();
        mat = mesh.material;
    }
    private void OnCollisionEnter(Collision collision)
    {
        if (collision.gameObject.name == "Myball")
            mat.color = new Color(0,0,0);
    }
    private void OnCollisionExit(Collision collision)
    {
        if (collision.gameObject.name == "Myball")
            mat.color = new Color(1,1,1);
    }