UnityFSM有限状态机(摘自简书Loyal_HAC)

• FSM主要用来配合animator实现NPC,AI或是UI的状态切换,如果状态比较少的话直接用switch或者只用animator也可以,不过为了可扩展性和学习的考虑还是写一下比较好,可惜自己太菜不会写,学习一波大佬的代码
• 先定义了一个抽象类BaseState

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();   
}

• 定义状态管理类

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

public class FsmManager
{
    private BaseState currentState;//当前状态
    private Dictionary<string, BaseState> playerStateDic = new Dictionary<string, BaseState>();//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();
        }
    }
}

• 然后每个状态写一个类,继承抽象类,可无限拓展

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

public class PlayerWalkState : BaseState
{
    //当一个子类继承父类的时候,子类构造函数默认调用父类的无参数构造函数,如果父类没有无参数的构造函数则报错.
    //构造函数是不能继承的,只能子类指定调用父类的构造函数,即:base()
    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");
       }
    }
}

• 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();
    } 
}