对于AI，我的初始想法非常easy，首先他要能动，而且是在地图里面动。 懂得撞墙后转弯，然后懂得射击，其它的没有了，基于这个想法，我首先创建了一个MyTank类，用于管理玩家的坦克的活动，然后创建AITank类，AITank类继承MyTank类。这种话。在AITank类上，仅仅须要添加AI就能够了。详细的状态机实现，就放到MyTank类上就可以。
首先来分析一下MyTank这个类，就从有限状态机開始吧。
一辆坦克的状态有以下几个：
protected enum State{Idle,LeftWalk,RightWalk,UpWalk,DownWalk,Fire};各自是：站立。向左走，向右走，向上走，向下走，开火。
然后就是分别实现每一个状态，首先是转向：
protected void UpdateRotate(State state){switch (state){case State.LeftWalk:this.transform.rotation = Quaternion.identity;this.transform.Rotate(Vector3.forward * m_fAngle);m_curAngle = Vector3.left;break;case State.RightWalk:this.transform.rotation = Quaternion.identity;this.transform.Rotate(Vector3.forward * -m_fAngle);m_curAngle = Vector3.right;break;case State.UpWalk:this.transform.rotation = Quaternion.identity;m_curAngle = Vector3.up;break;case State.DownWalk:this.transform.rotation = Quaternion.identity;this.transform.Rotate(Vector3.forward * m_fAngle * 2);m_curAngle = Vector3.down;break;}}然后是行走和开火：
public virtual void UpdateState(){Debug.Log(m_sName + ":UpdateState()");switch (m_curState){case State.Idle:break;case State.LeftWalk:this.transform.position += Vector3.left * Time.deltaTime * m_fMoveSpeed;break;case State.UpWalk:this.transform.position += Vector3.up * Time.deltaTime * m_fMoveSpeed;break;case State.DownWalk:this.transform.position += Vector3.down * Time.deltaTime * m_fMoveSpeed;break;case State.RightWalk:this.transform.position += Vector3.right * Time.deltaTime * m_fMoveSpeed;break;case State.Fire:doFire();break;}} protected virtual void doFire(){GameObject bullet = Instantiate(m_gBullet) as GameObject;bullet.name = m_sName + "Bullet";bullet.GetComponent<CBullet>().m_vDirection = m_curAngle;bullet.GetComponent<CBullet>().m_fMoveSpeed = m_fMoveSpeed + 1.0f;bullet.transform.position = new Vector3(this.transform.position.x, this.transform.position.y,0);Destroy(bullet, 5.0f);}设计为虚函数的原因是。AITank须要重写这个函数。
然后就须要监听各个按键，我设定为，按下A,W,S,D为方向键。松开就停止移动。然后按下K则开火，所以在Update函数里面应该这么实现：
void Update(){SetCurState(State.Idle);//转向if (Input.GetKey(KeyCode.A)){UpdateRotate(State.LeftWalk);SetCurState(State.LeftWalk);}if (Input.GetKey(KeyCode.W)){UpdateRotate(State.UpWalk);SetCurState(State.UpWalk);}if (Input.GetKey(KeyCode.S)){UpdateRotate(State.DownWalk);SetCurState(State.DownWalk);}if (Input.GetKey(KeyCode.D)){UpdateRotate(State.RightWalk);SetCurState(State.RightWalk);}if (Input.GetKeyDown(KeyCode.K)){SetCurState(State.Fire);}UpdateState();}当中SetCurState这个函数是用来设置当前状态的，而且把上一次的状态也存储起来，方便使用。
protected void SetCurState(State curState){if (curState != m_curState)m_lastState = m_curState;m_curState = curState;}最后就到了一些碰撞检測的函数了，比如，碰到敌人的子弹就生命值减一，生命值为0了就宣布游戏结束。
void OnTriggerEnter2D(Collider2D other){Debug.Log(m_sName + " OnTriggerEnter : " + other.gameObject.name);//被打中了if (other.gameObject.name == "AIBullet"){Destroy(other.gameObject);if (Camera.main.GetComponent<CCamera>().ReduceMyLeft() > 0){GameObject temp = Instantiate(m_BoomAnimation, this.gameObject.transform.position, Quaternion.identity) as GameObject;Destroy(temp, 0.5f);string name = this.gameObject.name;GameObject temp_tank = Instantiate(this.gameObject, m_initPosition, Quaternion.identity) as GameObject;temp_tank.name = name;}else{//你输了Camera.main.GetComponent<CCamera>().m_bIsLose = true;}Destroy(this.gameObject);}}上面就是整个MyTank的实现过程了
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
以下到了AITank的实现，AITank主要是加入一些触发器，比如检測到碰撞就转弯，每隔两秒就发射子弹等等，作为一个很easy的AI，就不须要考虑那么多。首先是碰撞检測：
void OnCollisionEnter2D(Collision2D coll){Debug.Log(m_sName + " OnCollisionEnter2D : " + coll.gameObject.name);ChangeStateFromWall();} void ChangeStateFromWall(){switch (m_curState){case State.Idle:SetCurState(State.DownWalk);break;case State.LeftWalk:SetCurState(State.UpWalk);break;case State.UpWalk:SetCurState(State.RightWalk);break;case State.DownWalk:SetCurState(State.LeftWalk);break;case State.RightWalk:SetCurState(State.DownWalk);break;case State.Fire:SetCurState(m_lastState);break;}this.UpdateRotate(m_curState);}
}这是一个循环转向的函数，假设当前方向是左边，就往上走，假设当前方向是上边。就往右走....；假设在开火状态的话。就返回上一状态。最后更新AI的角度。
然后到开火，开火的设定很easy，调用到一个函数：InvokeRepeating。这个是一个反复定时器。函数原型为：
void InvokeRepeating (string methodName,float time,float repeatRate) 第一个參数是传入的方法。第二个參数是在几秒后開始。第三个參数是開始后每隔几秒反复运行。
我们须要的是在AI坦克生成后一秒发射子弹 然后周期是每隔两秒发射一次。所以在Start函数中应该这么写：
//每隔2秒开一次火InvokeRepeating("doFire", 1, 2); protected override void doFire(){base.doFire();}
这样，就完毕了每两秒发射一发子弹的功能了。
上面就是AI的基本功能了，以后能够慢慢优化它。使它成为一个强大的AI。
项目源代码：【跟我一起学Unity3D】做一个2D的90坦克大战之各种各样的墙<<附上项目源代码>>
