游戏简单控制逻辑 一个轻量级的状态机

出处：http://blog.csdn.net/u010019717
author：孙广东 时间：2015.3.25
关于状态机这种设计模式不用多介绍了，网上有很多这方面的介绍，特别是FSM。
现在是我实现一个轻量级的状态机。

using System;
using System.Collections.Generic;

namespace Gamelogic
{
	/**
	一个轻量级的状态机。
	要使用它：
	-# 定义您自己的label。枚举Enums可能是最好的选择。
	-# 构造一个新的状态机state machin，通常是在 MonoBehaviour 的Start方法中。
	-# 添加的各种状态和对应的delegates。
	-# 从 MonoBehaviour 的Update方法调用状态机Update方法。
	-# 在状态机transition转换状态时调用 ChangeState 方法（你可以调用此方法，从一个state delegates，或任何其他地方）
	-# 状态发生变化时，对现有状态执行关闭 OnStop，然后OnStart开启新状态，之后新的状态每帧更新中调用 OnUpdate 方法
	*/
	public sealed class StateMachine<TLabel>
	{
		private class State
		{
			public readonly Action onStart;
			public readonly Action onUpdate;
			public readonly Action onStop;
			public readonly TLabel label;

			public State(TLabel label, Action onStart, Action onUpdate, Action onStop)
			{
				this.onStart = onStart;
				this.onUpdate = onUpdate;
				this.onStop = onStop;
				this.label = label;
			}
		}

		private readonly Dictionary<TLabel, State> stateDictionary;
		private State currentState;

		/**
			Returns the label of the current state.
		*/

		public TLabel CurrentState
		{
			get { return currentState.label; }

			/**@version1_2*/
			set { ChangeState(value); }
		}

		/**
			Constructs a new StateMachine.
		*/

		public StateMachine()
		{
			stateDictionary = new Dictionary<TLabel, State>();
		}

		/**
			Adds a state, and the delegates that should run 
			when the state starts, stops, 
			and when the state machine is updated.

			Any delegate can be null, and wont be executed.
		*/
		public void AddState(TLabel label, Action onStart, Action onUpdate, Action onStop)
		{
			stateDictionary[label] = new State(label, onStart, onUpdate, onStop);
		}

		/**
			Changes the state from the existing one to the state with the given label.
		*/
		private void ChangeState(TLabel newState)
		{
			if (currentState != null && currentState.onStop != null)
			{
				currentState.onStop();
			}

			currentState = stateDictionary[newState];

			if (currentState.onStart != null)
			{
				currentState.onStart();
			}
		}

		/**
			This method should be called every frame. 
		*/
		public void Update()
		{
			if (currentState != null && currentState.onUpdate != null)
			{
				currentState.onUpdate();
			}
		}
	}
}

使用的例子 很简单，cube的两种状态转换。 每种状态有不同的行为表现：

using System.Collections;
using UnityEngine;

namespace Gamelogic.Examples
{
	public class Cube : MonoBehaviour 
	{

		public enum CubeStates 
		{
			Swivel,
			MoveStraight
		}

		private StateMachine<CubeStates> stateMachine;
		private float moveSpeed = 1;
		private float switchTime = 3; 
		private float swivelSpeed = 2;

		public void Start()
		{
			stateMachine = new StateMachine<CubeStates>();

			stateMachine.AddState(CubeStates.Swivel, OnSwivelStart, OnSwivelUpdate, OnSwivelStop);
			stateMachine.AddState(CubeStates.MoveStraight, null, OnMoveStraightUpdate, null);

			stateMachine.CurrentState = CubeStates.MoveStraight;

			StartCoroutine(SwitchStates());
		}

		public IEnumerator SwitchStates()
		{
			while (true)
			{
				stateMachine.CurrentState = CubeStates.Swivel;
				yield return new WaitForSeconds(switchTime);

				stateMachine.CurrentState = CubeStates.MoveStraight;
				yield return new WaitForSeconds(switchTime);
			}
		}

		public void Update()
		{
			stateMachine.Update();
		}

		public void OnGUI()
		{
			GUILayout.TextField(stateMachine.CurrentState.ToString());
		}

		public void OnMoveStraightUpdate()
		{
			float dx = -Time.deltaTime * moveSpeed;

			transform.TranslateX(dx);
		}

		public void OnSwivelUpdate()
		{
			float dx = Time.deltaTime*moveSpeed;
			float y = Mathf.Sin(swivelSpeed * transform.position.x * 2 * Mathf.PI/switchTime);

			transform.TranslateX(dx);
			transform.SetY(y);
		}

		public void OnSwivelStart()
		{
			GetComponent<Renderer>().material.color = Color.red;
		}

		public void OnSwivelStop()
		{
			GetComponent<Renderer>().material.color = Color.green;
			transform.SetY(0); //recallibrate
		}
	}
}

就是这样的很简单的状态机。