使用有限状态机（FSM）编写的敌人AI

 using UnityEngine;
 using System.Collections;
 
 public class AttackState : FSMState
 {
     public AttackState()
     {
         stateID = FSMStateID.Attacking;
     }
 
     public override void Reason(Transform player, Transform npc)
     {
         if (npc.GetComponent<AIController>().stateInfo.normalizedTime >= 1.0f && npc.GetComponent<AIController>().stateInfo.IsName("Attack"))
             npc.GetComponent<AIController>().SetTransition(Transition.AttackOver);
     }
 
     public override void Act(Transform player, Transform npc)
     {
     }
 }

 using UnityEngine;
 using System.Collections;
 
 public class DeadState : FSMState
 {
     public DeadState()
     {
         stateID = FSMStateID.Dead;
     }
 
     public override void Reason(Transform player, Transform npc)
     {
 
     }
 
     public override void Act(Transform player, Transform npc)
     {
                 Animation animComponent = npc.GetComponent<Animation>();
                 //animComponent.CrossFade("death");
     }
 }

 using UnityEngine;
 using System.Collections;
 
 public class MoveState : FSMState
 {
     float rotateTime;
     float curSpeed;
     public MoveState()
     {
         stateID = FSMStateID.Move;
 
         curSpeed = 1.0f;
         rotateTime = 0f;
     }
 
     public override void Reason(Transform player, Transform npc)
     {
         float distance = Vector3.Distance(player.position, npc.position);
         if (distance <= )
         {
             if (npc.GetComponent<AIController>().attackCd == 0f)
             {
                 npc.GetComponent<AIController>().SetTransition(Transition.ReachPlayer);
                 npc.GetComponent<AIController>().attackCd = 5.0f;
             }
         }
     }
 
     public override void Act(Transform player, Transform npc)
     {
         rotateTime -= Time.deltaTime;
         if (rotateTime <= )
         {
             rotateTime = 3.0f;
             Vector3 toTargetV3 = (player.position - npc.position).normalized;
             float direction = Vector3.Dot(toTargetV3, npc.forward);
             Vector3 u = Vector3.Cross(toTargetV3, npc.forward);
             if (direction > ) { direction = 1f; }
             if (direction < -) { direction = -1f; }
             if (Mathf.Abs(direction) == 1f)
                 return;
             direction = Mathf.Acos(direction) * Mathf.Rad2Deg;
             npc.rotation = npc.rotation * Quaternion.Euler(new Vector3(, direction * (u.y >=  ? - : ), ));
         }
 
         float distance = Vector3.Distance(player.position, npc.position);
         if (distance >= )
         {
             npc.GetComponent<AIController>().animator.SetFloat("Blend", 1f);
             curSpeed = 2f;
         }
         else if (distance <  && distance >= )
         {
             npc.GetComponent<AIController>().animator.SetFloat("Blend", 0.5f);
             curSpeed = 1f;
         }
         else
         {
             npc.GetComponent<AIController>().animator.SetFloat("Blend", 0f);
             curSpeed = ;
         }
         npc.Translate(npc.transform.forward * Time.deltaTime * curSpeed, Space.World);
     }
 }

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 /// <summary>
 /// This class is adapted and modified from the FSM implementation class available on UnifyCommunity website
 /// The license for the code is Creative Commons Attribution Share Alike.
 /// It's originally the port of C++ FSM implementation mentioned in Chapter01 of Game Programming Gems 1
 /// You're free to use, modify and distribute the code in any projects including commercial ones.
 /// Please read the link to know more about CCA license @http://creativecommons.org/licenses/by-sa/3.0/
 /// </summary>
 
 //定义枚举，为可能的转换分配编号
 public enum Transition
 {
     SawPlayer = , //看到玩家
     ReachPlayer,   //接近玩家
     LostPlayer,    //玩家离开视线
     NoHealth,      //死亡
     AttackOver,    //结束攻击
 }
 
 /// <summary>
 /// 定义枚举，为可能的状态分配编号ID
 /// </summary>
 public enum FSMStateID
 {
     Move = ,
     Attacking,       //攻击编号
     Patrolling ,  //巡逻编号
     Chasing,         //追逐编号
     Dead,           //死亡编号
 }
 
 public class AdvancedFSM : FSM
 {
     //FSM中的所有状态组成的列表
     private List<FSMState> fsmStates;
     //当前状态的编号
     //The fsmStates are not changing directly but updated by using transitions
     private FSMStateID currentStateID;
     public FSMStateID CurrentStateID { get { return currentStateID; } }
     //当前状态
     private FSMState currentState;
     public FSMState CurrentState { get { return currentState; } }
 
     public AdvancedFSM()
     {
         //新建一个空的状态列表
         fsmStates = new List<FSMState>();
     }
 
     /// <summary>
     ///向状态列表中加入一个新的状态
     /// </summary>
     public void AddFSMState(FSMState fsmState)
     {
         //检查要加入的新状态是否为空，如果空就报错
         if (fsmState == null)
         {
             Debug.LogError("FSM ERROR: Null reference is not allowed");
         }
 
         // First State inserted is also the Initial state
         //   the state the machine is in when the simulation begins
         //如果插入的这个状态时，列表还是空的，那么将它加入列表并返回
         if (fsmStates.Count == )
         {
             fsmStates.Add(fsmState);
             currentState = fsmState;
             currentStateID = fsmState.ID;
             return;
         }
 
         // 检查要加入的状态是否已经在列表里，如果是，报错返回
         foreach (FSMState state in fsmStates)
         {
             if (state.ID == fsmState.ID)
             {
                 Debug.LogError("FSM ERROR: Trying to add a state that was already inside the list");
                 return;
             }
         }
         //如果要加入的状态不在列表中，将它加入列表
         fsmStates.Add(fsmState);
     }
 
     //从状态中删除一个状态
     public void DeleteState(FSMStateID fsmState)
     {
         // 搜索整个状态列表，如果要删除的状态在列表中，那么将它移除，否则报错
         foreach (FSMState state in fsmStates)
         {
             if (state.ID == fsmState)
             {
                 fsmStates.Remove(state);
                 return;
             }
         }
         Debug.LogError("FSM ERROR: The state passed was not on the list. Impossible to delete it");
     }
 
     /// <summary>
     /// 根据当前状态，和参数中传递的转换，转换到新状态
     /// </summary>
     public void PerformTransition(Transition trans)
     {
         // 根绝当前的状态类，以Trans为参数调用它的GetOutputState方法
         //确定转换后的新状态
         FSMStateID id = currentState.GetOutputState(trans);        
 
         //  将当前状态编号设置为刚刚返回的新状态编号
         currentStateID = id;
 
         //根绝状态编号查找状态列表，将当前状态设置为查找到的状态
         foreach (FSMState state in fsmStates)
         {
             if (state.ID == currentStateID)
             {
                 currentState = state;
                 break;
             }
         }
     }
 }

 using UnityEngine;
 using System.Collections;
 
 public class FSM : MonoBehaviour
 {
         //玩家位置
         protected Transform playerTransform;
 
         //下一个巡逻点
         protected Vector3 destPos;
 
         //巡逻点表单
         protected GameObject[] pointList;
 
         //子弹信息
         protected float shootRate;
         protected float elapsedTime;
 
         protected virtual void Initialize() {}
         protected virtual void FSMUpdate() {}
         protected virtual void FSMFixedUpdate() {}
 
         //初始化信息
         void Start()
         {
                 Initialize();
         }
 
     // 循环执行子类FSMUpdate方法
         void Update ()
         {
                 FSMUpdate();
         }
 
         void FixedUpdate()
         {
                 FSMFixedUpdate();
         }
 }

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 /// <summary>
 /// This class is adapted and modified from the FSM implementation class available on UnifyCommunity website
 /// The license for the code is Creative Commons Attribution Share Alike.
 /// It's originally the port of C++ FSM implementation mentioned in Chapter01 of Game Programming Gems 1
 /// You're free to use, modify and distribute the code in any projects including commercial ones.
 /// Please read the link to know more about CCA license @http://creativecommons.org/licenses/by-sa/3.0/
 
 /// This class represents the States in the Finite State System.
 /// Each state has a Dictionary with pairs (transition-state) showing
 /// which state the FSM should be if a transition is fired while this state
 /// is the current state.
 /// Reason method is used to determine which transition should be fired .
 /// Act method has the code to perform the actions the NPC is supposed to do if it磗 on this state.
 /// </summary>
 public abstract class FSMState
 {
     //字典，字典中每一项都记录了一个“转换-状态”对 的信息
     protected Dictionary<Transition, FSMStateID> map = new Dictionary<Transition, FSMStateID>();
     //状态编号ID
     protected FSMStateID stateID;
     public FSMStateID ID { get { return stateID; } }
 
     /// <summary>
     /// 向字典添加项，每项是一个"转换--状态"对
     /// </summary>
     /// <param name="transition"></param>
     /// <param name="id"></param>
     public void AddTransition(Transition transition, FSMStateID id)
     {
         //检查这个转换(可以看做是字典的关键字)是否在字典里
         if (map.ContainsKey(transition))
         {
             //一个转换只能对应一个新状态
             Debug.LogWarning("FSMState ERROR: transition is already inside the map");
             return;
         }
         //如果不在字典，那么将这个转换和转换后的状态作为一个新的字典项，加入字典
         map.Add(transition, id);
     }
 
     /// <summary>
     /// 从字典中删除项
     /// </summary>
     /// <param name="trans"></param>
     public void DeleteTransition(Transition trans)
     {
         // 检查是否在字典中，如果在，移除
         if (map.ContainsKey(trans))
         {
             map.Remove(trans);
             return;
         }
         //如果要删除的项不在字典中，报告错误
         Debug.LogError("FSMState ERROR: Transition passed was not on this State List");
     }
 
     /// <summary>
     /// 通过查询字典，确定在当前状态下，发生trans转换时，应该转换到新的状态编号并返回
     /// </summary>
     /// <param name="trans"></param>
     /// <returns></returns>
     public FSMStateID GetOutputState(Transition trans)
     {
         return map[trans];
     }
 
     /// <summary>
     /// 用来确定是否需要转换到其他状态，应该发生哪个转换
     /// </summary>
     /// <param name="player"></param>
     /// <param name="npc"></param>
     public abstract void Reason(Transform player, Transform npc);
 
     /// <summary>
     /// 定义了在本状态的角色行为，移动，动画等
     /// </summary>
     /// <param name="player"></param>
     /// <param name="npc"></param>
     public abstract void Act(Transform player, Transform npc);
 }

 using UnityEngine;
 using System.Collections;
 
 public class AIController : AdvancedFSM
 {
     private int health;
     public Animator animator;
     public AnimatorStateInfo stateInfo;
     public float attackCd;
     //Initialize the Finite state machine for the NPC tank
     protected override void Initialize()
     {
         health = ;
 
         elapsedTime = 0.0f;
         shootRate = 0.5f;
         attackCd = 0f;
 
         //Get the target enemy(Player)
         GameObject objPlayer = GameObject.FindGameObjectWithTag("Player");
         playerTransform = objPlayer.transform;
 
         if (!playerTransform)
             print("Player doesn't exist.. Please add one with Tag named 'Player'");
         animator = this.GetComponentInChildren<Animator>();
         //Start Doing the Finite State Machine
         ConstructFSM();
     }
 
     //Update each frame
     protected override void FSMUpdate()
     {
         //Check for health
         elapsedTime += Time.deltaTime;
         if (attackCd > )
         {
             attackCd -= Time.deltaTime;
             if (attackCd <= )
                 attackCd = ;
         }
     }
 
     protected override void FSMFixedUpdate()
     {
         stateInfo = animator.GetCurrentAnimatorStateInfo();
         CurrentState.Reason(playerTransform, transform);
         CurrentState.Act(playerTransform, transform);
     }
 
     public void SetTransition(Transition t)
     {
         PerformTransition(t);
         animator.SetInteger("StateI", (int)CurrentStateID);
     }
 
     private void ConstructFSM()
     {
         //Get the list of points
         pointList = GameObject.FindGameObjectsWithTag("PatrolPoint");
 
         Transform[] waypoints = new Transform[pointList.Length];
         int i = ;
         foreach(GameObject obj in pointList)
         {
             waypoints = obj.transform;
             i++;
         }
 
         MoveState move = new MoveState();
         move.AddTransition(Transition.ReachPlayer,FSMStateID.Attacking);
 
         AttackState attack = new AttackState();
         attack.AddTransition(Transition.AttackOver,FSMStateID.Move);
 
         AddFSMState(move);
         AddFSMState(attack);
     }
 
     /// <summary>
     /// Check the collision with the bullet
     /// </summary>
     /// <param name="collision"></param>
     void OnCollisionEnter(Collision collision)
     {
         //Reduce health
         if (collision.gameObject.tag == "Bullet")
         {
             health -= ;
 
             if (health <= )
             {
                 Debug.Log("Switch to Dead State");
                 SetTransition(Transition.NoHealth);
             }
         }
     }
 
     // Shoot the bullet
     public void ShootBullet()
     {
         if (elapsedTime >= shootRate)
         {
             elapsedTime = 0.0f;
         }
     }
 }

 using UnityEngine;
 using System.Collections;
 
 public class CameraFollow : MonoBehaviour
 {
     public Transform target;
     public Vector3 offest;
 
     void LateUpdate()
     {
         transform.position = target.position + offest;
     }
 }