设计模式学习之路(九) ------ 有限状态机

• 理论:http://wiki.unity3d.com/index.php/Finite_State_Machine
  

实例:

       战士AI,使用有限状态机实现

战士有限战斗机状态虚类,后面的状态都要继承于它:

public enum SoldierTransition //转换的条件
{
    NullTansition = 0,
    SeeEnemy,
    NoEnmey,
    CanAttack
}
public enum SoldierStateID //状态ID,保证唯一
{
    NullState,
    Idle,
    Chase,
    Attack
}
/// <summary>
/// 战士有限战斗机状态虚类,后面的状态都要继承于它
/// </summary>
public abstract class ISoldierState
{
    //条件有多个,而字典只需包含当前状态能够转换的状态对应的条件即可
    protected Dictionary<SoldierTransition, SoldierStateID> mMap = new Dictionary<SoldierTransition, SoldierStateID>();
    protected SoldierStateID mStateID;   //唯一,根据ID寻找状态,实例化状态的时候设置
    protected ICharacter mCharacter;  
    protected SoldierFSMSytem mFSM; //状态管理对象
    /// <summary>
    /// 初始化
    /// </summary>
    /// <param name="fsm"></param>
    /// <param name="character"></param>
    public ISoldierState(SoldierFSMSytem fsm,ICharacter character)
    {
        mFSM = fsm;
        mCharacter = character;
    }

    public SoldierStateID stateID { get { return mStateID; } }
    /// <summary>
    /// 添加转换条件
    /// </summary>
    /// <param name="trans"></param>
    /// <param name="id"></param>
    public void AddTransition(SoldierTransition trans, SoldierStateID id)
    {
        if (trans == SoldierTransition.NullTansition)
        {
            Debug.LogError("SoldierState Error: trans不能为空"); return;
        }
        if (id == SoldierStateID.NullState)
        {
            Debug.LogError("SoldierState Error: id状态ID不能为空"); return;
        }
        if (mMap.ContainsKey(trans))
        {
            Debug.LogError("SoldierState Error: " + trans + " 已经添加上了"); return;
        }
        mMap.Add(trans, id);
    }

    /// <summary>
    /// 删除转换条件
    /// </summary>
    /// <param name="trans"></param>
    public void DeleteTransition(SoldierTransition trans)
    {
        if (mMap.ContainsKey(trans) == false)
        {
            Debug.LogError("删除转换条件的时候， 转换条件：[" + trans + "]不存在"); return;
        }
        mMap.Remove(trans);
    }
    //当前字典是否包含转换条件,包含则将ID返回,可以根据这个函数判断条件可以转换成什么状态
    public SoldierStateID GetOutPutState(SoldierTransition trans)
    {
        if (mMap.ContainsKey(trans) == false)
        {
            return SoldierStateID.NullState;
        } else
        {
            return mMap[trans];
        }
    }
    //进入状态之前要做的事情
    public virtual void DoBeforeEntering() { }
    //离开状态之前要做的事情
    public virtual void DoBeforeLeaving() { }

    //Reason Act都是每帧执行
    //判断是否需要转换成其他状态
    public abstract void Reason( List<ICharacter> targets );
    //处理当前状态的操作
    public abstract void Act(List<ICharacter> targets);
}

状态机的拥有者,管理状态:

using System;
using System.Collections.Generic;
using System.Text;
using UnityEngine;
/// <summary>
/// 状态机的拥有者,管理状态
/// </summary>
public class SoldierFSMSytem
{
    //状态列表
    private List<ISoldierState> mStates = new List<ISoldierState>();

    private ISoldierState mCurrentState;
    //当前状态
    public ISoldierState currentState { get { return mCurrentState; } }
    //添加状态,每次创建出一个状态都要给FSMSytem进行管理
    public void AddState(params ISoldierState[] states)
    {
        foreach (ISoldierState s in states)
        {
            AddState(s);
        }
    }
    public void AddState(ISoldierState state)
    {
        if (state == null)
        {
            Debug.LogError("要添加的状态为空"); return;
        }
        if (mStates.Count == 0)
        {
            mStates.Add(state);
            mCurrentState = state;
            return;
        }
        foreach (ISoldierState s in mStates)
        {
            if (s.stateID == state.stateID)
            {
                Debug.LogError("要添加的状态ID[" + s.stateID + "]已经添加"); return;
            }
        }
        mStates.Add(state);
    }
    //删除状态
    public void DeleteState(SoldierStateID stateID)
    {
        if (stateID == SoldierStateID.NullState)
        {
            Debug.LogError("要删除的状态ID为空" + stateID); return;
        }
        foreach (ISoldierState s in mStates)
        {
            if (s.stateID == stateID)
            {
                mStates.Remove(s);
                return;
            }
        }
        Debug.LogError("要删除的StateID不存在集合中:" + stateID);
    }
    //根据转换条件转换状态,state只要调用这个方法将转换条件传过来即可
    public void PerformTransition(SoldierTransition trans)
    {
        if (trans == SoldierTransition.NullTansition)
        {
            Debug.LogError("要执行的转换条件为空 ： " + trans); return;
        }
        SoldierStateID nextStateID = mCurrentState.GetOutPutState(trans); //当前状态有没有满足转换条件的状态ID
        if (nextStateID == SoldierStateID.NullState)
        {
            Debug.LogError("在转换条件 [" + trans + "] 下，没有对应的转换状态"); return;
        }
        //遍历状态列表
        foreach (ISoldierState s in mStates)
        {
            if (s.stateID == nextStateID)
            {
                mCurrentState.DoBeforeLeaving(); //执行状态离开的函数
                mCurrentState = s; //设置当前
                mCurrentState.DoBeforeEntering();
                return;
            }
        }
    }
}

追逐状态:

using System;
using System.Collections.Generic;
using System.Text;
using UnityEngine;

public class SoldierChaseState:ISoldierState
{
    public SoldierChaseState(SoldierFSMSytem fsm, ICharacter c) : base(fsm, c) { mStateID = SoldierStateID.Chase; }
    public override void Reason(List<ICharacter> targets)
    {
        if (targets == null || targets.Count == 0)
        {
            mFSM.PerformTransition(SoldierTransition.NoEnmey); return;
        }
        float distance = Vector3.Distance(targets[0].position, mCharacter.position);
        if (distance <= mCharacter.atkRange)
        {
            mFSM.PerformTransition(SoldierTransition.CanAttack); //转换
        }
    }

    public override void Act(List<ICharacter> targets)
    {
        //当前状态要做的判断操作
        if (targets != null && targets.Count > 0)
        {
            mCharacter.MoveTo(targets[0].position);
        }
    }
}

有限状态机控制类:

//有限状态机控制类
public abstract class ISoldier:ICharacter
{
    protected SoldierFSMSytem mFSMSystem;//有限状态机管理对象

    public ISoldier():base()
    {
        MakeFSM();
    }

    
    //更新状态机
    public override void UpdateFSMAI( List<ICharacter> targets )
    {
        if (mIsKilled) return;
        mFSMSystem.currentState.Reason(targets);
        mFSMSystem.currentState.Act(targets);
    }
    /// <summary>
    /// 制作状态机,在战士初始化的时候被调用
    /// </summary>
    private void MakeFSM()
    {
        mFSMSystem = new SoldierFSMSytem();

        SoldierIdleState idleState = new SoldierIdleState(mFSMSystem, this);
        idleState.AddTransition(SoldierTransition.SeeEnemy, SoldierStateID.Chase);

        SoldierChaseState chaseState = new SoldierChaseState(mFSMSystem, this);
        chaseState.AddTransition(SoldierTransition.NoEnmey, SoldierStateID.Idle);
        chaseState.AddTransition(SoldierTransition.CanAttack, SoldierStateID.Attack);

        SoldierAttackState attackState = new SoldierAttackState(mFSMSystem, this);
        attackState.AddTransition(SoldierTransition.NoEnmey, SoldierStateID.Idle);
        attackState.AddTransition(SoldierTransition.SeeEnemy, SoldierStateID.Chase);

        mFSMSystem.AddState(idleState,chaseState,attackState);
    }
    public override void Update()
    {
        UpdateFSMAI();
    }
}