http://www.manew.com/thread-89637-1-1.html
**為什么用有限狀態機?
**
??之前做過一款跑酷游戲,跑酷角色有很多狀態:跑、跳、二段跳、死亡等等。一開始是使用if/switch來切換狀態,但是每次角色添加一個狀態（提前沒規劃好),所有狀態處理相關的代碼就會指數級增長,那樣就會嗅出代碼的壞味道了。在這種處理狀態并且狀態數量不是特別多的情況下,自然就想到了引入狀態機。
優點:
??1.使代碼整潔,狀態容易擴展和管理。
??2.可復用。
??3.還沒想到.....
缺點:
??1.也沒想到......
**什么是有限狀態機?
**
??解釋不清楚,看了下百度百科。反正是一種數據結構,一個解決問題的工具。
??從百度百科可以看到,有限狀態機最最最基礎的概念有兩個:狀態和轉移。
??從剛才跑酷的例子來講,跑、跳、二段跳等這些就是角色的狀態。
如圖所示:
主角從跑狀態切換到跳狀態,從跳狀態切換到二段跳狀態,這里的切換就是指狀態的轉移。狀態的轉移是有條件的,比如主角從跑狀態不可以直接切換到二段跳狀態。但是可以從二段跳狀態切換到跑狀態。
??另外,一個基本的狀態有:進入狀態、退出狀態、接收輸入、轉移狀態等動作。但是僅僅作為跑酷的角色的狀態管理來說,只需要轉移狀態就足夠了。有興趣的同學可以自行擴展。
**如何實現?
**
??恰好之前看到過一個還算簡易的實現(簡易就是指我能看得懂- -,希望大家也是),原版是用lua實現的,我的跑酷游戲是用C#實現的,所以直接貼出C#代碼。
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
public class FSM {
// 定義函數指針類型
public delegate void FSMTranslationCallfunc(); /// <summary>
/// 狀態類
/// </summary>
public class FSMState
{
public string name;
public FSMState(string name)
{
this.name = name;
}
/// <summary>
/// 存儲事件對應的條轉
/// </summary>
public Dictionary <string,FSMTranslation> TranslationDict = new Dictionary<string,FSMTranslation>();
}
/// <summary>
/// 跳轉類
/// </summary>
public class FSMTranslation
{
public FSMState fromState;
public string name;
public FSMState toState;
public FSMTranslationCallfunc callfunc; // 回調函數
public FSMTranslation(FSMState fromState,string name, FSMState toState,FSMTranslationCallfunc callfunc)
{
this.fromState = fromState;
this.toState = toState;
this.name = name;
this.callfunc = callfunc;
}
}
// 當前狀態
private FSMState mCurState;
Dictionary <string,FSMState> StateDict = new Dictionary<string,FSMState>();
/// <summary>
/// 添加狀態
/// </summary>
/// <param name="state">State.</param>
public void AddState(FSMState state)
{
StateDict [state.name] = state;
}
/// <summary>
/// 添加條轉
/// </summary>
/// <param name="translation">Translation.</param>
public void AddTranslation(FSMTranslation translation)
{
StateDict [translation.fromState.name].TranslationDict [translation.name] = translation;
}
/// <summary>
/// 啟動狀態機
/// </summary>
/// <param name="state">State.</param>
public void Start(FSMState state)
{
mCurState = state;
}
/// <summary>
/// 處理事件
/// </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);
}
}
}
測試代碼(需自行修改):
// 創建狀態
FSM.FSMState idleState = new FSM.FSMState("idle"); // Idle, 閑置
FSM.FSMState runState = new FSM.FSMState("run"); // Run, 跑
FSM.FSMState jumpState = new FSM.FSMState("jump"); // Jump, 一段跳
FSM.FSMState doubleJumpState = new FSM.FSMState("double_jump"); // DoubleJump, 二段跳
FSM.FSMState dieState = new FSM.FSMState("die"); // Die, 掛彩
// 創建跳轉
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);
// 添加狀態
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);
// 添加跳轉
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);[mw_shl_code=csharp,true] // 創建狀態
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");
// 創建跳轉
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);
// 添加狀態
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);
// 添加跳轉
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);
貼上代碼地址址:https://github.com/liangxiegame/QFramework/blob/master/Script/DesignPattern/QFSM.cs
??就這些,想要進一步擴展的話,可以給FSMState類添加EnterCallback和ExitCallback等委托,然后在FSM的HandleEvent方法中進行調用。當時對跑酷的項目來說夠用了,接沒繼續擴展了,我好懶- -,懶的借口是:沒有最好的設計,只有最適合的設計,233333。
