[Unity]有限状态机FSM

概念

1.有限状态机：状态机由状态寄存器和组合逻辑电路构成，能够根据控制信号按照预先设定的状态进行状态转移，是协调相关信号动作、完成特定操作的控制中心。(百度复制的，哈哈哈)
2.我的理解就是玩游戏主角有走，跑，跳，死亡等的状态，同一个时候只能有一个状态，当满足一个特定的条件就会从一个状态变成另一个状态

关系图.png

设计状态机

不同的状态都会有进入状态，更新状态，离开状态几个行为，所以我们定义一个抽象类把这些特性提取出来

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

public abstract class BaseState
{    
    protected FsmManager _fsmManager;
    //构造函数
    public BaseState(FsmManager fsmManager)
    {
        _fsmManager = fsmManager;
    }
    //进入状态
    public abstract void EnterState();
    //离开状态
    public abstract void ExitState();
    //更新状态
    public abstract void UpdateState();
    
}

然后我们需要一个状态管理的类来管理，状态的注册，两个状态的转换，设置默认状态和更新状态

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

public class FsmManager
{
    private BaseState currentState;//当前状态
    private Dictionary playerStateDic = new Dictionary();//储存状态的字典
    public FsmManager() { }
    //状态注册
    public void Region(string statename, BaseState state)
    {
        if (!playerStateDic.ContainsKey(statename))
        {
            playerStateDic.Add(statename, state);
        }
    }
    //设置默认状态
    public void SetDefaultState(string statename)
    {
        if (playerStateDic.ContainsKey(statename))
        {
            currentState = playerStateDic[statename];
            currentState.EnterState();
        }
    }
    //改变状态
    public void ChangeState(string statename)
    {
        if (playerStateDic.ContainsKey(statename))
        {
            if (currentState != null)
            {
                if (!(currentState == playerStateDic[statename]))
                {
                    currentState.ExitState();
                    currentState = playerStateDic[statename];
                    currentState.EnterState();
                }

            }
        }
    }
   //更新状态
    public void UpdateState()
    {
        if (currentState != null)
        {
            currentState.UpdateState();
        }
    }
}

再编写不同状态的类，例如走的状态

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

public class PlayerWalkState : BaseState
{
    public PlayerWalkState(FsmManager fsmManager) : base(fsmManager) { }
    public override void EnterState()
    {       
    }

    public override void ExitState()
    {        
    }

    public override void UpdateState()
    {
       //例如当满足条件A的时候状态从走变成跑
       if (A){
                    _fsmManager.ChangeState("run");
       }
    }
}

后续其他状态增加相应的类就好了

测试

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

public class FSM: MonoBehaviour
{

    // Use this for initialization
    public FsmManager fsmManager;   
    void Start()
    {     
       
        fsmManager = new FsmManager();
        //注册状态
        fsmManager.Region("walk", new PlayerWalkState(fsmManager, playerAnim));
        fsmManager.Region("run", new PlayerRunState(fsmManager, playerAnim));
        fsmManager.Region("jump", new PlayerJumpState(fsmManager, playerAnim));
        //设置默认状态
        fsmManager.SetDefaultState("walk");
    }

    // Update is called once per frame
    void Update()
    {
        //更新状态
        fsmManager.UpdateState();
    } 
}