public void OnCollisionStay(Collision collision)
        {
            ++eraseNum;//当たった回数

            if (waitCount < wait)
            {
                return;
            }
            waitCount = 0;


            foreach (var p in collision.contacts)
            {
                var canvas = p.otherCollider.GetComponent <InkCanvas>();

                if (canvas != null)
                {
                    canvas.Paint(brush, p.point);

                    HitPoint hitPont = new HitPoint();
                    hitPont.canvas         = canvas;
                    hitPont.point          = p.point;
                    hitPont.remainingFrame = 5;
                    hitPointList.Add(hitPont);
                }
            }
        }
        public void FixedUpdate()
        {
            ++waitCount;

            for (int i = 0; i < hitPointList.Count; i++)
            {
                HitPoint hitPoint = hitPointList[i];

                hitPoint.remainingFrame--;

                if (hitPoint.remainingFrame <= 0)
                {
                    hitPoint.canvas.Erase(brush, hitPoint.point);
                    hitPointList.RemoveAt(i);
                }
            }
            GameObject tama  = GameObject.Find("shell");
            GameObject tama2 = GameObject.Find("BBball");

            Destroy(tama);
            Destroy(tama2);
        }