Unity 游戏框架搭建 2017 (四) 简易有限状态机

本文转载自查看原文 2017-07-04 13:11 803 blog

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: 1. 使代码整洁,状态容易扩展和管理。 2. 可复用。 3. 还没想到..... 缺点: 1. 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。

此篇的内容就这些。

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