Unity3D 状态机

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using System;
using System.Collections.Generic;

public class StateMachine<T> where T : struct, IComparable {

    private class State {
        public readonly T state;
        public readonly Action onEnter;
        public readonly Action onUpdate;
        public readonly Action onExit;

        public State(T state, Action onEnter, Action onUpdate, Action onExit) {
            this.state = state;
            this.onEnter = onEnter;
            this.onUpdate = onUpdate;
            this.onExit = onExit;
        }
    }

    private readonly Dictionary<T, State> stateDictionary;

    private State currentState;

    public T CurrentState {
        get { return currentState.state; }
        set { ChangeState (value); }
    }

    public StateMachine() {
        if (!typeof(T).IsEnum) {
            throw new ArgumentException ("类型参数必须为枚举");
        }
        stateDictionary = new Dictionary<T, State> ();
    }

    public void AddState (T state, Action onEnter, Action onUpdate, Action onExit) {
        stateDictionary.Add (state, new State (state, onEnter, onUpdate, onExit));
    }

    private void ChangeState(T newState) {
        if (currentState != null && currentState.state.CompareTo(newState) == 0) {
            return;
        }

        if (currentState != null && currentState.onExit != null) {
            currentState.onExit ();
        }

        currentState = stateDictionary [newState];

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

    public void Update() {
        if (currentState != null && currentState.onUpdate != null) {
            currentState.onUpdate ();
        }
    }
}

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

public class Test : MonoBehaviour {

    public enum CharacterState {
        Idle,
        Walk,
        Run,
    }

    private StateMachine<CharacterState> stateMachine;

    private WaitForSeconds waitSeconds;

    // Use this for initialization
    void Start () {
        stateMachine = new StateMachine<CharacterState> ();
        stateMachine.AddState (CharacterState.Idle, Idle_Enter, null, Idle_Exit);
        stateMachine.AddState (CharacterState.Walk, Walk_Enter, Walk_Update, Walk_Exit);
        stateMachine.AddState (CharacterState.Run, Run_Enter, null, Run_Exit);
        stateMachine.CurrentState = CharacterState.Idle;
        StartCoroutine (DoChange ());
    }

    IEnumerator DoChange () {
        waitSeconds = new WaitForSeconds (1f);
        yield return waitSeconds;
        stateMachine.CurrentState = CharacterState.Run;
        yield return waitSeconds;
        stateMachine.CurrentState = CharacterState.Walk;
        yield return waitSeconds;
        stateMachine.CurrentState = CharacterState.Idle;
    }
    
    // Update is called once per frame
    void Update () {
        stateMachine.Update ();
    }

    public void Idle_Enter () {
        Debug.Log ("Idle enter ...");
    }

    public void Idle_Exit () {
        Debug.Log ("Idle exit ***");
    }

    public void Walk_Enter () {
        Debug.Log ("Walk enter ...");
    }

    public void Walk_Update () {
        Debug.Log ("Walk update");
    }

    public void Walk_Exit () {
        Debug.Log ("Walk exit ***");
    }

    public void Run_Enter () {
        Debug.Log ("Run enter ...");
    }

    public void Run_Exit () {
        Debug.Log ("Run exit ***");
    }
}

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using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
using System.Runtime.CompilerServices;
using UnityEngine;
using Object = System.Object;

public class StateMachineRunner : MonoBehaviour
{
    private List<IStateMachine> stateMachineList = new List<IStateMachine>();

    /// <summary>
    /// Creates a stateMachine token object which is used to managed to the state of a monobehaviour. 
    /// </summary>
    /// <typeparam name="T">An Enum listing different state transitions</typeparam>
    /// <param name="component">The component whose state will be managed</param>
    /// <returns></returns>
    public StateMachine<T> Initialize<T>(MonoBehaviour component) where T : struct, IConvertible, IComparable
    {
        var fsm = new StateMachine<T>(this, component);

        stateMachineList.Add(fsm);

        return fsm;
    }

    /// <summary>
    /// Creates a stateMachine token object which is used to managed to the state of a monobehaviour. Will automatically transition the startState
    /// </summary>
    /// <typeparam name="T">An Enum listing different state transitions</typeparam>
    /// <param name="component">The component whose state will be managed</param>
    /// <param name="startState">The default start state</param>
    /// <returns></returns>
    public StateMachine<T> Initialize<T>(MonoBehaviour component, T startState) where T : struct, IConvertible, IComparable
    {
        var fsm = Initialize<T>(component);

        fsm.ChangeState(startState);

        return fsm;
    }

    void FixedUpdate()
    {
        for (int i = 0; i < stateMachineList.Count; i++)
        {
            var fsm = stateMachineList[i];
            if(!fsm.IsInTransition && fsm.Component.enabled) fsm.CurrentStateMap.FixedUpdate();
        }
    }

    void Update()
    {
        for (int i = 0; i < stateMachineList.Count; i++)
        {
            var fsm = stateMachineList[i];
            if (!fsm.IsInTransition && fsm.Component.enabled)
            {
                fsm.CurrentStateMap.Update();
            }
        }
    }

    void LateUpdate()
    {
        for (int i = 0; i < stateMachineList.Count; i++)
        {
            var fsm = stateMachineList[i];
            if (!fsm.IsInTransition && fsm.Component.enabled)
            {
                fsm.CurrentStateMap.LateUpdate();
            }
        }
    }

    //void OnCollisionEnter(Collision collision)
    //{
    //  if(currentState != null && !IsInTransition)
    //  {
    //      currentState.OnCollisionEnter(collision);
    //  }
    //}

    public static void DoNothing()
    {
    }

    public static void DoNothingCollider(Collider other)
    {
    }

    public static void DoNothingCollision(Collision other)
    {
    }

    public static IEnumerator DoNothingCoroutine()
    {
        yield break;
    }
}

public class StateMapping
{
    public object state;

    public bool hasEnterRoutine;
    public Action EnterCall = StateMachineRunner.DoNothing;
    public Func<IEnumerator> EnterRoutine = StateMachineRunner.DoNothingCoroutine;

    public bool hasExitRoutine;
    public Action ExitCall = StateMachineRunner.DoNothing;
    public Func<IEnumerator> ExitRoutine = StateMachineRunner.DoNothingCoroutine;

    public Action Finally = StateMachineRunner.DoNothing;
    public Action Update = StateMachineRunner.DoNothing;
    public Action LateUpdate = StateMachineRunner.DoNothing;
    public Action FixedUpdate = StateMachineRunner.DoNothing;
    public Action<Collision> OnCollisionEnter = StateMachineRunner.DoNothingCollision;

    public StateMapping(object state)
    {
        this.state = state;
    }
}

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using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
using System.Runtime.CompilerServices;
using UnityEngine;
using Object = System.Object;

public enum StateTransition
{
    Safe,
    Overwrite,
}

public interface IStateMachine
{
    MonoBehaviour Component { get; }
    StateMapping CurrentStateMap { get; }
    bool IsInTransition { get; }
}

public class StateMachine<T> : IStateMachine where T : struct, IConvertible, IComparable
{
    public event Action<T> Changed;

    private StateMachineRunner engine;
    private MonoBehaviour component;

    private StateMapping lastState;
    private StateMapping currentState;
    private StateMapping destinationState;

    private Dictionary<object, StateMapping> stateLookup;

    private bool isInTransition = false;
    private IEnumerator currentTransition;
    private IEnumerator exitRoutine;
    private IEnumerator enterRoutine;
    private IEnumerator queuedChange;

    public StateMachine(StateMachineRunner engine, MonoBehaviour component)
    {
        this.engine = engine;
        this.component = component;

        //Define States
        var values = Enum.GetValues(typeof(T));
        if (values.Length < 1) { throw new ArgumentException("Enum provided to Initialize must have at least 1 visible definition"); }

        stateLookup = new Dictionary<object, StateMapping>();
        for (int i = 0; i < values.Length; i++)
        {
            var mapping = new StateMapping((Enum) values.GetValue(i));
            stateLookup.Add(mapping.state, mapping);
        }

        //Reflect methods
        var methods = component.GetType().GetMethods(BindingFlags.Instance | BindingFlags.DeclaredOnly | BindingFlags.Public |
                                  BindingFlags.NonPublic);

        //Bind methods to states
        var separator = "_".ToCharArray();
        for (int i = 0; i < methods.Length; i++)
        {
            if (methods[i].GetCustomAttributes(typeof(CompilerGeneratedAttribute), true).Length != 0)
            {
                continue;
            }

            var names = methods[i].Name.Split(separator);

            //Ignore functions without an underscore
            if (names.Length <= 1)
            {
                continue;
            }

            Enum key;
            try
            {
                key = (Enum) Enum.Parse(typeof(T), names[0]);
            }
            catch (ArgumentException)
            {
                //Not an method as listed in the state enum
                continue;
            }

            var targetState = stateLookup[key];

            switch (names[1])
            {
                case "Enter":
                    if (methods[i].ReturnType == typeof(IEnumerator))
                    {
                        targetState.hasEnterRoutine = true;
                        targetState.EnterRoutine = CreateDelegate<Func<IEnumerator>>(methods[i], component);
                    }
                    else
                    {
                        targetState.hasEnterRoutine = false;
                        targetState.EnterCall = CreateDelegate<Action>(methods[i], component);
                    }
                    break;
                case "Exit":
                    if (methods[i].ReturnType == typeof(IEnumerator))
                    {
                        targetState.hasExitRoutine = true;
                        targetState.ExitRoutine = CreateDelegate<Func<IEnumerator>>(methods[i], component);
                    }
                    else
                    {
                        targetState.hasExitRoutine = false;
                        targetState.ExitCall = CreateDelegate<Action>(methods[i], component);
                    }
                    break;
                case "Finally":
                    targetState.Finally = CreateDelegate<Action>(methods[i], component);
                    break;
                case "Update":
                    targetState.Update = CreateDelegate<Action>(methods[i], component);
                    break;
                case "LateUpdate":
                    targetState.LateUpdate = CreateDelegate<Action>(methods[i], component);
                    break;
                case "FixedUpdate":
                    targetState.FixedUpdate = CreateDelegate<Action>(methods[i], component);
                    break;
                case "OnCollisionEnter":
                    targetState.OnCollisionEnter = CreateDelegate<Action<Collision>>(methods[i], component);
                    break;
            }
        }

        //Create nil state mapping
        currentState = new StateMapping(null);
    }

    private V CreateDelegate<V>(MethodInfo method, Object target) where V : class
    {
        var ret = (Delegate.CreateDelegate(typeof(V), target, method) as V);

        if (ret == null)
        {
            throw new ArgumentException("Unabled to create delegate for method called " + method.Name);
        }
        return ret;
    }

    public void ChangeState(T newState)
    {
        ChangeState(newState, StateTransition.Safe);
    }

    public void ChangeState(T newState, StateTransition transition)
    {
        if (stateLookup == null)
        {
            throw new Exception("States have not been configured, please call initialized before trying to set state");
        }

        if (!stateLookup.ContainsKey(newState))
        {
            throw new Exception("No state with the name " + newState.ToString() + " can be found. Please make sure you are called the correct type the statemachine was initialized with");
        }

        var nextState = stateLookup[newState];

        if (currentState == nextState) return;

        //Cancel any queued changes.
        if (queuedChange != null)
        {
            engine.StopCoroutine(queuedChange);
            queuedChange = null;
        }

        switch (transition)
        {
            //case StateMachineTransition.Blend:
            //Do nothing - allows the state transitions to overlap each other. This is a dumb idea, as previous state might trigger new changes. 
            //A better way would be to start the two couroutines at the same time. IE don't wait for exit before starting start.
            //How does this work in terms of overwrite?
            //Is there a way to make this safe, I don't think so? 
            //break;
            case StateTransition.Safe:
                if (isInTransition)
                {
                    if (exitRoutine != null) //We are already exiting current state on our way to our previous target state
                    {
                        //Overwrite with our new target
                        destinationState = nextState;
                        return;
                    }

                    if (enterRoutine != null) //We are already entering our previous target state. Need to wait for that to finish and call the exit routine.
                    {
                        //Damn, I need to test this hard
                        queuedChange = WaitForPreviousTransition(nextState);
                        engine.StartCoroutine(queuedChange);
                        return;
                    }
                }
                break;
            case StateTransition.Overwrite:
                if (currentTransition != null)
                {
                    engine.StopCoroutine(currentTransition);
                }
                if (exitRoutine != null)
                {
                    engine.StopCoroutine(exitRoutine);
                }
                if (enterRoutine != null)
                {
                    engine.StopCoroutine(enterRoutine);
                }

                //Note: if we are currently in an EnterRoutine and Exit is also a routine, this will be skipped in ChangeToNewStateRoutine()
                break;
        }


        if ((currentState != null && currentState.hasExitRoutine) || nextState.hasEnterRoutine)
        {
            isInTransition = true;
            currentTransition = ChangeToNewStateRoutine(nextState, transition);
            engine.StartCoroutine(currentTransition);
        }
        else //Same frame transition, no coroutines are present
        {
            if (currentState != null)
            {
                currentState.ExitCall();
                currentState.Finally();
            }

            lastState = currentState;
            currentState = nextState;
            if (currentState != null)
            {
                currentState.EnterCall();
                if (Changed != null)
                {
                    Changed((T) currentState.state);
                }
            }
            isInTransition = false;
        }
    }

    private IEnumerator ChangeToNewStateRoutine(StateMapping newState, StateTransition transition)
    {
        destinationState = newState; //Chache this so that we can overwrite it and hijack a transition

        if (currentState != null)
        {
            if (currentState.hasExitRoutine)
            {
                exitRoutine = currentState.ExitRoutine();

                if (exitRoutine != null && transition != StateTransition.Overwrite) //Don't wait for exit if we are overwriting
                {
                    yield return engine.StartCoroutine(exitRoutine);
                }

                exitRoutine = null;
            }
            else
            {
                currentState.ExitCall();
            }

            currentState.Finally();
        }

        lastState = currentState;
        currentState = destinationState;

        if (currentState != null)
        {
            if (currentState.hasEnterRoutine)
            {
                enterRoutine = currentState.EnterRoutine();

                if (enterRoutine != null)
                {
                    yield return engine.StartCoroutine(enterRoutine);
                }

                enterRoutine = null;
            }
            else
            {
                currentState.EnterCall();
            }

            //Broadcast change only after enter transition has begun. 
            if (Changed != null)
            {
                Changed((T) currentState.state);
            }
        }

        isInTransition = false;
    }

    IEnumerator WaitForPreviousTransition(StateMapping nextState)
    {
        while (isInTransition)
        {
            yield return null;
        }

        ChangeState((T) nextState.state);
    }

    public T LastState
    {
        get
        {
            if (lastState == null) return default(T);

            return (T) lastState.state;
        }
    }

    public T State
    {
        get { return (T) currentState.state; }
    }

    public bool IsInTransition
    {
        get { return isInTransition; }
    }

    public StateMapping CurrentStateMap
    {
        get { return currentState; }
    }

    public MonoBehaviour Component
    {
        get { return component; }
    }

    /// <summary>
    /// Inspects a MonoBehaviour for state methods as definied by the supplied Enum, and returns a stateMachine instance used to trasition states.
    /// </summary>
    /// <param name="component">The component with defined state methods</param>
    /// <returns>A valid stateMachine instance to manage MonoBehaviour state transitions</returns>
    public static StateMachine<T> Initialize(MonoBehaviour component)
    {
        var engine = component.GetComponent<StateMachineRunner>();
        if (engine == null) engine = component.gameObject.AddComponent<StateMachineRunner>();

        return engine.Initialize<T>(component);
    }

    /// <summary>
    /// Inspects a MonoBehaviour for state methods as definied by the supplied Enum, and returns a stateMachine instance used to trasition states. 
    /// </summary>
    /// <param name="component">The component with defined state methods</param>
    /// <param name="startState">The default starting state</param>
    /// <returns>A valid stateMachine instance to manage MonoBehaviour state transitions</returns>
    public static StateMachine<T> Initialize(MonoBehaviour component, T startState)
    {
        var engine = component.GetComponent<StateMachineRunner>();
        if (engine == null) engine = component.gameObject.AddComponent<StateMachineRunner>();

        return engine.Initialize<T>(component, startState);
    }

}

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using UnityEngine;
using System.Collections;

public class Main : MonoBehaviour
{
    //Declare which states we'd like use
    public enum States
    {
        Init,
        Countdown,
        Play,
        Win,
        Lose
    }

    public float health = 100;
    public float damage = 20;

    private float startHealth;

    private StateMachine<States> fsm;

    private void Awake()
    {
        startHealth = health;

        //Initialize State Machine Engine       
        fsm = StateMachine<States>.Initialize(this, States.Init);
    }

    void OnGUI()
    {
        //Example of polling state 
        var state = fsm.State;

        GUILayout.BeginArea(new Rect(50,50,120,40));

        if(state == States.Init && GUILayout.Button("Start"))
        {
            fsm.ChangeState(States.Countdown);
        }
        if(state == States.Countdown)
        {
            GUILayout.Label("Look at Console");
        }
        if(state == States.Play)
        {
            if(GUILayout.Button("Force Win"))
            {
                fsm.ChangeState(States.Win);
            }
            
            GUILayout.Label("Health: " + Mathf.Round(health).ToString());
        }
        if(state == States.Win || state == States.Lose)
        {
            if(GUILayout.Button("Play Again"))
            {
                fsm.ChangeState(States.Countdown);
            }
        }

        GUILayout.EndArea();
    }

    private void Init_Enter()
    {
        Debug.Log("Waiting for start button to be pressed");
    }

    //We can return a coroutine, this is useful animations and the like
    private IEnumerator Countdown_Enter()
    {
        health = startHealth;

        Debug.Log("Starting in 3...");
        yield return new WaitForSeconds(0.5f);
        Debug.Log("Starting in 2...");
        yield return new WaitForSeconds(0.5f);
        Debug.Log("Starting in 1...");
        yield return new WaitForSeconds(0.5f);

        fsm.ChangeState(States.Play);
    }

    private void Play_Enter()
    {
        Debug.Log("FIGHT!");
    }

    private void Play_Update()
    {
        health -= damage * Time.deltaTime;
    
        if(health < 0)
        {
            fsm.ChangeState(States.Lose);
        }
    }

    void Play_Exit()
    {
        Debug.Log("Game Over");
    }

    void Lose_Enter()
    {
        Debug.Log("Lost");
    }

    void Win_Enter()
    {
        Debug.Log("Won");
    }
}