Unity 游戏框架搭建 (四) 简易有限状态机

为什么用有限状态机?

之前做过一款跑酷游戏,跑酷角色有很多状态:跑、跳、二段跳、死亡等等。一开始是使用if/switch来切换状态,但是每次角色添加一个状态（提前没规划好),所有状态处理相关的代码就会指数级增长,那样就会嗅出代码的坏味道了。在这种处理状态并且状态数量不是特别多的情况下,自然就想到了引入状态机。

优点:

• 使代码整洁,状态容易扩展和管理。
• 可复用。
• 还没想到…..
  缺点:
• 也没想到……

什么是有限状态机?

解释不清楚,看了下百度百科。反正是一种数据结构,一个解决问题的工具。
从百度百科可以看到,有限状态机最最最基础的概念有两个:状态和转移。
从刚才跑酷的例子来讲,跑、跳、二段跳等这些就是角色的状态。

如图所示:

主角从跑状态切换到跳状态,从跳状态切换到二段跳状态,这里的切换就是指状态的转移。状态的转移是有条件的,比如主角从跑状态不可以直接切换到二段跳状态。但是可以从二段跳状态切换到跑状态。

另外,一个基本的状态有:进入状态、退出状态、接收输入、转移状态等动作。但是仅仅作为跑酷的角色的状态管理来说,只需要转移状态就足够了。有兴趣的同学可以自行扩展。

如何实现?

恰好之前看到过一个还算简易的实现(简易就是指我能看得懂- -,希望大家也是),原版是用lua实现的,我的跑酷游戏是用C# 实现的,所以直接贴出C#代码。

using UnityEngine;using System.Collections;using System.Collections.Generic;public class FSM {    // 定义函数指针类型    public delegate void FSMTranslationCallfunc();    /// <summary>    /// 状态类    /// </summary>    public class FSMState    {        public string name;        public FSMState(string name)        {            this.name = name;        }        /// <summary>        /// 存储事件对应的条转        /// </summary>        public Dictionary <string,FSMTranslation> TranslationDict = new Dictionary<string,FSMTranslation>();    }    /// <summary>    /// 跳转类    /// </summary>    public class FSMTranslation    {        public FSMState fromState;        public string name;        public FSMState toState;        public FSMTranslationCallfunc callfunc; // 回调函数        public FSMTranslation(FSMState fromState,string name, FSMState toState,FSMTranslationCallfunc callfunc)        {            this.fromState = fromState;            this.toState   = toState;            this.name = name;            this.callfunc = callfunc;        }    }    // 当前状态    private FSMState mCurState;    Dictionary <string,FSMState> StateDict = new Dictionary<string,FSMState>();    /// <summary>    /// 添加状态    /// </summary>    /// <param name="state">State.</param>    public void AddState(FSMState state)    {        StateDict [state.name] = state;    }    /// <summary>    /// 添加条转    /// </summary>    /// <param name="translation">Translation.</param>    public void AddTranslation(FSMTranslation translation)    {        StateDict [translation.fromState.name].TranslationDict [translation.name] = translation;    }    /// <summary>    /// 启动状态机    /// </summary>    /// <param name="state">State.</param>    public void Start(FSMState state)    {        mCurState = state;    }    /// <summary>    /// 处理事件    /// </summary>    /// <param name="name">Name.</param>    public void HandleEvent(string name)    {        if (mCurState != null && mCurState.TranslationDict.ContainsKey(name)) {            Debug.LogWarning ("fromState:" + mCurState.name);            mCurState.TranslationDict [name].callfunc ();            mCurState = mCurState.TranslationDict [name].toState;            Debug.LogWarning ("toState:" + mCurState.name);        }    }}

测试代码(需自行修改):

//        Idle,               闲置//        Run,                跑//        Jump,               一段跳//        DoubleJump,         二段跳//        Die,                挂彩        // 创建状态        FSM.FSMState idleState = new FSM.FSMState("idle");        FSM.FSMState runState  = new FSM.FSMState("run");        FSM.FSMState jumpState = new FSM.FSMState("jump");        FSM.FSMState doubleJumpState = new FSM.FSMState("double_jump");        FSM.FSMState dieState  = new FSM.FSMState("die");        // 创建跳转        FSM.FSMTranslation touchTranslation1 = new FSM.FSMTranslation(runState,"touch_down",jumpState,Jump);        FSM.FSMTranslation touchTranslation2 = new FSM.FSMTranslation(jumpState,"touch_down",doubleJumpState,DoubleJump);        FSM.FSMTranslation landTranslation1 = new FSM.FSMTranslation(jumpState,"land",runState,Run);        FSM.FSMTranslation landTranslation2 = new FSM.FSMTranslation(doubleJumpState,"land",runState,Run);        // 添加状态        PlayerModel.Instance ().fsm.AddState (idleState);        PlayerModel.Instance ().fsm.AddState (runState);        PlayerModel.Instance ().fsm.AddState (jumpState);        PlayerModel.Instance ().fsm.AddState (doubleJumpState);        PlayerModel.Instance ().fsm.AddState (dieState);        // 添加跳转        PlayerModel.Instance ().fsm.AddTranslation (touchTranslation1);        PlayerModel.Instance ().fsm.AddTranslation (touchTranslation2);        PlayerModel.Instance ().fsm.AddTranslation (landTranslation1);        PlayerModel.Instance ().fsm.AddTranslation (landTranslation2);        PlayerModel.Instance ().fsm.Start (runState);

就这些,想要进一步扩展的话,可以给FSMState类添加EnterCallback和ExitCallback等委托,然后在FSM的HandleEvent方法中进行调用。当时对跑酷的项目来说够用了,接没继续扩展了,我好懒- -,懒的借口是:没有最好的设计,只有最适合的设计,233333。

附:我的框架QFramework地址

单例库QSingleton地址

转载请注明地址:凉鞋的笔记

微信公众号:liangxiegame

output/writing/unity游戏框架搭建