简单的有限状态机设计---下

于 2016-05-09 09:57:06 发布
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分类专栏： 人机交互(AI)
上篇给大家介绍了一个自定义的简单的使用switch语句实现的有限状态机，这次给大家介绍下一个简单的FSM框架， 使用简单的FSM框架设计，可以避免我们使用switch实现的代码冗余，我们可以做到一个状态一个类，高效直观的区分开来。这个框架可以在unitycommunity.com找到 ，地址是http://wiki.unity3d.com/index.php?title=Finite_State_Machine    首先我们还是使用昨天用过的例子来制作，
 
图表显示了怪物AI 的一些列状态，在框架实现方式中，表里面每一个“当前状态”都对应着一个状态类。
比如 “巡逻”状态对应一个PatrolState类，“追逐”状态对应着ChaseState类，等。。。 这些状态类都继承同一个父类 FSMState类。
    每个状态类都拥有自己的“字典”，里面存储着当前状态所拥有的“转换--新状态”对，表明这个状态下，如果发生某个“转换”事件，
即表中的“输入”，状态机就会转移到何种的新状态。
   例如，在PatrolState类中，字典会有一个SawPlayer-Chase的项，表明在巡逻状态PatrolState下，如果看到玩家SawPlayer，
那么转换到追逐状态ChaseState。因此，可以把“输入” 看做是字典的关键字，而转移得到的新状态可以认为是根据关键字查询
字典得到的结果。
    另外，FSM框架中还有一个重要的类---AdvancedFSM类，它负责管理所有这些状态类如 巡逻，追逐，攻击 等。
    好，下面我们开始看看具体的实现，首先，FSMState 类是所有状态类的基类，它的每个派生类都代表了FSM中的某个状态，
状态类中具有添加转换，删除转换的方法，用于管理记录这些转换。
在FSMState类中，包含了一个字典对象，称为Map，可以在类中的AddTransition方法和DeleteTransition方法添加或删除“转换-状态”对。
这个类还包括Reason方法和Act方法。其中，Reason方法用来确定是否需要转换到其他状态，应该发生哪个转换；
Act方法定义了在本状态的角色行为，比如移动，播放动画等。
下面是FSMState 的代码

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[/b][/size]
[size=4][b] 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; } }
     //下面需要用到的，与各状态相关的变量
     //目标点的位置
     protected Vector3 destPos;
     //巡逻点的数组，存储巡逻要经过的点
     protected Transform[] waypoints;
     //转向速度
     protected float curRotSpeed;
     //移动速度
     protected float curSpeed;
     //AI与玩家距离小于该值，开始追逐
     protected float chaseDistance = 40.0f;
     //小于这个就攻击
     protected float attackDistance = 20.0f;
     //巡逻小于这值，就认为到达巡逻点了
     protected float arriveDistance = 3.0f;
 
     /// <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);
         Debug.Log( "Added : " + transition + " with ID : " + 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);
 
     /// <summary>
     /// 寻找下一个巡逻点
     /// </summary>
     public void FindNextPoint()
     {
         //Debug.Log("Finding next point");
         int rndIndex = Random.Range(0, waypoints.Length);
         Vector3 rndPosition = Vector3.zero;
         destPos = waypoints[rndIndex].position + rndPosition;
     }
 
     /// <summary>
     /// Check whether the next random position is the same as current tank position
     /// </summary>
     /// <param name="pos">position to check</param>
     /*
     protected bool IsInCurrentRange(Transform trans, Vector3 pos)
     {
         float xPos = Mathf.Abs(pos.x - trans.position.x);
         float zPos = Mathf.Abs(pos.z - trans.position.z);
 
         if (xPos <= 50 && zPos <= 50)
             return true;
 
         return false;
     }*/
}[b]
[/b]


然后是AdvancedFSM类，它是FSM类的派生类，负责管理FSMState的派生类，并且随着当前状态和输入，进行状态更新，
需要注意的是这个类不能有Start(),Update(),和FixedUpdate()函数，否则将会覆盖基类的函数

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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 = 0, //看到玩家
     ReachPlayer,   //接近玩家
     LostPlayer,    //玩家离开视线
     NoHealth,      //死亡
}
 
/// <summary>
/// 定义枚举，为可能的状态分配编号ID
/// </summary>
public enum FSMStateID
{   
     Patrolling = 0,  //巡逻编号
     Chasing,         //追逐编号
     Attacking,       //攻击编号
     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 == 0)
         {
             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 ;
             }
         }
     }
}
  


手码了好多注释，累 
在这种视线中，一个AdvanceFSM类可以管理和使用任意数目的FSMState，两个类共同为用户提供了一个通用的FSM框架，
它们能够支持多种状态，多种FSM输入以及多种状态转移。
然后下面我们开始说其他的状态类实现，和上篇的例子不同，在这个FSM框架中，AI角色的状态在不同的类里面实现，
且都是FSMState的派生类，每个类都需要实现Reason和Act方法
代码里面我把播放动画之类的注释了，为能简单演示一下FSM框架的强大，
下面是巡逻类代码
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using UnityEngine;
using System.Collections;
 
public class PatrolState : FSMState
{
     public PatrolState(Transform[] wp)
     {
         waypoints = wp;
         stateID = FSMStateID.Patrolling;
 
         curRotSpeed = 6.0f;
         curSpeed = 80.0f;
     }
 
     public override void Reason(Transform player, Transform npc)
     {
         //Check the distance with player tank
         //When the distance is near, transition to chase state
         if (Vector3.Distance(npc.position, player.position) <= chaseDistance)
         {
             Debug.Log( "Switch to Chase State" );
             npc.GetComponent<AIController>().SetTransition(Transition.SawPlayer);
         }
     }
 
     public override void Act(Transform player, Transform npc)
     {
         //Find another random patrol point if the current point is reached
         
         if (Vector3.Distance(npc.position, destPos) <= arriveDistance)
         {
             Debug.Log( "Reached to the destination point\ncalculating the next point" );
             FindNextPoint();
         }
 
         //Rotate to the target point
         Quaternion targetRotation = Quaternion.LookRotation(destPos - npc.position);
         npc.rotation = Quaternion.Slerp(npc.rotation, targetRotation, Time.deltaTime * curRotSpeed);
 
         //Go Forward       
         CharacterController controller = npc.GetComponent<CharacterController>();
         controller.SimpleMove(npc.transform.forward * Time.deltaTime * curSpeed);
 
         Animation animComponent = npc.GetComponent<Animation>();
         //animComponent.CrossFade("Walk");
     }
}


然后是追逐类 
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using UnityEngine;
using System.Collections;
 
public class ChaseState : FSMState
{
     public ChaseState(Transform[] wp)
     {
         waypoints = wp;
         stateID = FSMStateID.Chasing;
 
         curRotSpeed = 6.0f;
         curSpeed = 160.0f;
 
         //find next Waypoint position
         FindNextPoint();
     }
 
     public override void Reason(Transform player, Transform npc)
     {
         //Set the target position as the player position
         destPos = player.position;
 
         //Check the distance with player tank
         //When the distance is near, transition to attack state
         float dist = Vector3.Distance(npc.position, destPos);
         if (dist <= attackDistance)
         {
             Debug.Log( "Switch to Attack state" );
             npc.GetComponent<AIController>().SetTransition(Transition.ReachPlayer);
         }
         //Go back to patrol is it become too far
         else if (dist >= chaseDistance)
         {
             Debug.Log( "Switch to Patrol state" );
             npc.GetComponent<AIController>().SetTransition(Transition.LostPlayer);
         }
     }
 
     public override void Act(Transform player, Transform npc)
     {
         //Rotate to the target point
         destPos = player.position;
 
         Quaternion targetRotation = Quaternion.LookRotation(destPos - npc.position);
         npc.rotation = Quaternion.Slerp(npc.rotation, targetRotation, Time.deltaTime * curRotSpeed);
 
         //Go Forward
         //npc.Translate(Vector3.forward * Time.deltaTime * curSpeed);
         CharacterController controller = npc.GetComponent<CharacterController>();
         controller.SimpleMove(npc.transform.forward * Time.deltaTime * curSpeed);
 
         Animation animComponent = npc.GetComponent<Animation>();
         //animComponent.CrossFade("Run");
     }
}



攻击类
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using UnityEngine;
using System.Collections;
 
public class AttackState : FSMState
{
     public AttackState(Transform[] wp)
     {
         waypoints = wp;
         stateID = FSMStateID.Attacking;
         curRotSpeed = 12.0f;
         curSpeed = 100.0f;
 
         //find next Waypoint position
         FindNextPoint();
     }
 
     public override void Reason(Transform player, Transform npc)
     {
         //Check the distance with the player tank
         float dist = Vector3.Distance(npc.position, player.position);
 
         if (dist >= attackDistance && dist < chaseDistance)
         {
             Debug.Log( "Switch to Chase State" );
             npc.GetComponent<AIController>().SetTransition(Transition.SawPlayer);
         }
         //Transition to patrol is the tank become too far
         else if (dist >= chaseDistance)
         {
             Debug.Log( "Switch to Patrol State" );
             npc.GetComponent<AIController>().SetTransition(Transition.LostPlayer);
         } 
     }
 
     public override void Act(Transform player, Transform npc)
     {
         //Set the target position as the player position
         destPos = player.position;       
 
         //Rotate to the target point
         Quaternion targetRotation = Quaternion.LookRotation(destPos - npc.position);
         npc.rotation = Quaternion.Slerp(npc.rotation, targetRotation, Time.deltaTime * curRotSpeed);
 
         //Shoot bullet towards the player
         Animation animComponent = npc.GetComponent<Animation>();
         //animComponent.CrossFade("StandingFire");
         npc.GetComponent<AIController>().ShootBullet();
 
     }
}



还是死亡类
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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");
     }
}


最后是一个控制类AIController 负责创建有限状态机，通过它控制AI角色
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using UnityEngine;
using System.Collections;
 
public class AIController : AdvancedFSM
{
     public GameObject Bullet;
     public Transform bulletSpawnPoint;
     private int health;
 
     //Initialize the Finite state machine for the NPC tank
     protected override void Initialize()
     {
         health = 100;
 
         elapsedTime = 0.0f;
         shootRate = 0.5f;
 
         //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'" );       
 
         //Start Doing the Finite State Machine
         ConstructFSM();
     }
 
     //Update each frame
     protected override void FSMUpdate()
     {
         //Check for health
         elapsedTime += Time.deltaTime;
     }
 
     protected override void FSMFixedUpdate()
     {
         CurrentState.Reason(playerTransform, transform);
         CurrentState.Act(playerTransform, transform);
     }
 
     public void SetTransition(Transition t)
     {
         PerformTransition(t);
     }
 
     private void ConstructFSM()
     {
         //Get the list of points
         pointList = GameObject.FindGameObjectsWithTag( "PatrolPoint" );
 
         Transform[] waypoints = new Transform[pointList.Length];
         int i = 0;
         foreach (GameObject obj in pointList)
         {
             waypoints[i] = obj.transform;
             i++;
         }
 
         PatrolState patrol = new PatrolState(waypoints);
         patrol.AddTransition(Transition.SawPlayer, FSMStateID.Chasing);
         patrol.AddTransition(Transition.NoHealth, FSMStateID.Dead);
 
         ChaseState chase = new ChaseState(waypoints);
         chase.AddTransition(Transition.LostPlayer, FSMStateID.Patrolling);
         chase.AddTransition(Transition.ReachPlayer, FSMStateID.Attacking);
         chase.AddTransition(Transition.NoHealth, FSMStateID.Dead);
 
         AttackState attack = new AttackState(waypoints);
         attack.AddTransition(Transition.LostPlayer, FSMStateID.Patrolling);
         attack.AddTransition(Transition.SawPlayer, FSMStateID.Chasing);
         attack.AddTransition(Transition.NoHealth, FSMStateID.Dead);
 
         DeadState dead = new DeadState();
         dead.AddTransition(Transition.NoHealth, FSMStateID.Dead);
 
         AddFSMState(patrol);
         AddFSMState(chase);
         AddFSMState(attack);
         AddFSMState(dead);
     }
 
     /// <summary>
     /// Check the collision with the bullet
     /// </summary>
     /// <param name="collision"></param>
     void OnCollisionEnter(Collision collision)
     {
         //Reduce health
         if (collision.gameObject.tag == "Bullet" )
         {
             health -= 50;
 
             if (health <= 0)
             {
                 Debug.Log( "Switch to Dead State" );
                 SetTransition(Transition.NoHealth);               
             }
         }
     }
 
 
     
     // Shoot the bullet   
     public void ShootBullet()
     {
         if (elapsedTime >= shootRate)
         {           
             GameObject bulletObj = Instantiate(Bullet, bulletSpawnPoint.position, transform.rotation) as GameObject;
             bulletObj.GetComponent<Bullet>().Go();
             elapsedTime = 0.0f;
         }
     }
}


好了，代码写完了，下面我们来布置场景，和上篇类似，不同的地方就是EnemyAI不用SimpleFSM，而更换为AIController。
其他都一样，然后运行 我们就可以看见一个AI在地图中巡逻，我们玩家上前 AI就会主动追过来，然后攻击，然后死亡。 

最后我们也上传一下源代码，里面有2个场景，1就是上篇的代码，2就是本次的代码。
FSM状态机就简单介绍到这里，下次学到什么再和大家分享.谢谢大家。
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