Unity-实现在防御塔在范围内只攻击先进来的

public Queue enemyQue;GameObject take_aim;float second;// Use this for initializationvoid Start () {    enemyQue = new Queue();}// Update is called once per framevoid Update () {    second += Time.deltaTime;    if (enemyQue.Count != 0)    {        take_aim = enemyQue.Peek() as GameObject;        //transform.LookAt(take_aim.transform.position, Vector3.up);        transform.forward = take_aim.transform.position - transform.position;        if (second > CreateTime)        {            take_aim.GetComponent<Move_enemy>().Hp -= Attack;            second -= CreateTime;        }        if (take_aim.GetComponent<Move_enemy>().Hp <= 0)        {            Destroy(take_aim);            enemyQue.Dequeue();        }    }}void OnTriggerEnter(Collider enemy){    if (enemy.tag == "Enemy")    {        enemyQue.Enqueue(enemy.gameObject);        //Debug.Log(enemyQue.Count + "入队");    }}void OnTriggerExit(Collider enemy){    if (enemyQue.Count != 0)    {        enemyQue.Dequeue();        //Debug.Log(enemyQue.Count + "结束");    }}