如何判断Unity协程Fade的结束状态并正确触发存档逻辑？

API 探路者

2026-8-21

Unity 淡入淡出协程与存档逻辑的同步问题

我在Unity项目里写了Fader和SavingGame两个脚本，需求是：按下K键触发屏幕淡入，点击UI按钮调用Save方法触发淡出，必须等淡出协程完全结束后，再执行StartSaving的存档逻辑。但现在用静态标志位isInState的方式经常逻辑混乱，会提前触发存档，想问下怎么正确判断Fade协程的结束状态（不管是淡入还是淡出完成），并在合适时机触发存档？

原始Fader脚本

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

public class Fader : MonoBehaviour
{
    public bool fadeAutomatically = false;
    public float fadeTime;
    public CanvasGroup canvasGroup;
    public static bool isInState = false;
    private Coroutine _currentRoutine;
    private bool _currentDirection;
    private bool _nextDirection;

    private void Start()
    {
        if (canvasGroup == null)
        {
            canvasGroup = GameObject.FindGameObjectWithTag("Loading Saved Game Description").GetComponent<CanvasGroup>();
        }
    }

    public void StartFade(bool isIn, bool autoSwitch)
    {
        if (_currentRoutine != null)
        {
            if (_currentDirection != isIn)
            {
                StopCoroutine(_currentRoutine);

                _currentRoutine = StartCoroutine(Fade(canvasGroup, isIn, autoSwitch));
            }
        }
        else
        {
            _currentRoutine = StartCoroutine(Fade(canvasGroup, isIn, autoSwitch));
        }
    }

    private void Update()
    {
        if (!fadeAutomatically)
        {
            if (Input.GetKeyDown(KeyCode.O))
            {
                StartFade(false,false);
            }

            if (Input.GetKeyDown(KeyCode.I))
            {
                StartFade(true,false);
            }
        }
        else
        {
            StartFade(_nextDirection,true);
        }
    }

    IEnumerator Fade(CanvasGroup canvasGroup, bool isIn, bool autoSwitch)
    {
        _currentDirection = isIn;

        var startValue = isIn ? 0 : 1;
        var targetValue = isIn ? 1 : 0;

        var elapsedTime = fadeTime * (isIn ? canvasGroup.alpha : (1 - canvasGroup.alpha));
        while (elapsedTime <= fadeTime)
        {
            canvasGroup.alpha = Mathf.Lerp(startValue, targetValue, elapsedTime / fadeTime);

            yield return null;

            elapsedTime += Time.deltaTime;
        }

        canvasGroup.alpha = targetValue;

        if (autoSwitch) _nextDirection = !isIn;

        _currentRoutine = null;

        if(isIn == false)
        {
            isInState = true;
        }
        else
        {

        }
    }
}

原始SavingGame脚本

using UnityEngine;
using System.Collections;
using System.IO;
using TMPro;

public class SavingGame : MonoBehaviour
{
    public int resWidth = 1920;
    public int resHeight = 1080;
    public SaveLoad saveLoad;
    public Fader fader;
    public TMP_InputField _inputField;

    private static int countName;

    private void Start()
    {
        countName = 0;
        
        string[] dirs = Directory.GetDirectories(Application.persistentDataPath + "\\" + "Saved Screenshots",
            "*.*", SearchOption.TopDirectoryOnly);

        if(dirs.Length > 0)
        {
            countName = dirs.Length;
        }
    }

    public static string ScreenShotName(int width, int height)
    {
        return string.Format("{0}/Saved Screenshots/SaveSlot{1} SavedGameSlot_{2}x{3}_{4}/SavedGameSlot_{1}x{2}_{3}.png",
            Application.persistentDataPath,
            countName,
            width, height, System.DateTime.Now.ToString("yyyy-MM-dd_HH-mm-ss"));
    }

    void Update()
    {
        if (Input.GetKeyDown("k"))
        {
            fader.StartFade(true, false);
        }

        if(Fader.isInState)
        {
            StartSaving();
            Fader.isInState = false;
        }
    }

    public void Save()
    {
        fader.StartFade(false, false);
    }

    public void StartSaving()
    {
        string filename = ScreenShotName(resWidth, resHeight);
        string directory = Path.GetDirectoryName(filename);
        Directory.CreateDirectory(directory);
        ScreenCapture.CaptureScreenshot(filename);
        string descriptionContent = _inputField.text;
        if (_inputField.text.Length != 0)
        {
            string descriptionFileFolder = directory + "\\" + "Description.txt";
            File.WriteAllText(descriptionFileFolder, descriptionContent);
        }
        StartCoroutine(saveLoad.SaveWithTime(directory, Path.GetFileNameWithoutExtension(filename) + ".savegame.txt"));

        countName++;
    }
}

解决方案：用回调/事件替代静态标志位

静态变量的问题在于全局共享，很容易被其他逻辑意外修改，导致状态判断出错。改用回调委托来通知协程结束，能精准控制时机，逻辑更可靠。

步骤1：修改Fader脚本

移除静态变量isInState
添加Action<bool>委托，用来通知外部淡入淡出完成（参数bool表示当前是淡入/淡出）
在Fade协程末尾触发这个委托

修改后的Fader脚本：

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

public class Fader : MonoBehaviour
{
    public bool fadeAutomatically = false;
    public float fadeTime;
    public CanvasGroup canvasGroup;
    // 新增：fade完成时触发的回调，参数isIn表示完成的是淡入(true)还是淡出(false)
    public Action<bool> OnFadeComplete;
    
    private Coroutine _currentRoutine;
    private bool _currentDirection;
    private bool _nextDirection;

    private void Start()
    {
        if (canvasGroup == null)
        {
            canvasGroup = GameObject.FindGameObjectWithTag("Loading Saved Game Description").GetComponent<CanvasGroup>();
        }
    }

    public void StartFade(bool isIn, bool autoSwitch)
    {
        if (_currentRoutine != null)
        {
            if (_currentDirection != isIn)
            {
                StopCoroutine(_currentRoutine);
                _currentRoutine = StartCoroutine(Fade(canvasGroup, isIn, autoSwitch));
            }
        }
        else
        {
            _currentRoutine = StartCoroutine(Fade(canvasGroup, isIn, autoSwitch));
        }
    }

    private void Update()
    {
        if (!fadeAutomatically)
        {
            if (Input.GetKeyDown(KeyCode.O))
            {
                StartFade(false,false);
            }

            if (Input.GetKeyDown(KeyCode.I))
            {
                StartFade(true,false);
            }
        }
        else
        {
            StartFade(_nextDirection,true);
        }
    }

    IEnumerator Fade(CanvasGroup canvasGroup, bool isIn, bool autoSwitch)
    {
        _currentDirection = isIn;

        var startValue = isIn ? 0 : 1;
        var targetValue = isIn ? 1 : 0;

        var elapsedTime = fadeTime * (isIn ? canvasGroup.alpha : (1 - canvasGroup.alpha));
        while (elapsedTime <= fadeTime)
        {
            canvasGroup.alpha = Mathf.Lerp(startValue, targetValue, elapsedTime / fadeTime);
            yield return null;
            elapsedTime += Time.deltaTime;
        }

        canvasGroup.alpha = targetValue;

        if (autoSwitch) _nextDirection = !isIn;
        _currentRoutine = null;

        // 触发回调，通知外部fade完成
        OnFadeComplete?.Invoke(isIn);
    }
}

步骤2：修改SavingGame脚本

在Start中订阅Fader的OnFadeComplete事件
实现回调方法，仅在淡出完成时执行存档
移除Update中对静态变量的判断
在OnDestroy中取消订阅，避免内存泄漏

修改后的SavingGame脚本：

using UnityEngine;
using System.Collections;
using System.IO;
using TMPro;

public class SavingGame : MonoBehaviour
{
    public int resWidth = 1920;
    public int resHeight = 1080;
    public SaveLoad saveLoad;
    public Fader fader;
    public TMP_InputField _inputField;

    private static int countName;

    private void Start()
    {
        countName = 0;
        
        string[] dirs = Directory.GetDirectories(Application.persistentDataPath + "\\" + "Saved Screenshots",
            "*.*", SearchOption.TopDirectoryOnly);

        if(dirs.Length > 0)
        {
            countName = dirs.Length;
        }

        // 订阅Fader的fade完成事件
        fader.OnFadeComplete += HandleFadeComplete;
    }

    private void OnDestroy()
    {
        // 取消订阅，防止内存泄漏
        fader.OnFadeComplete -= HandleFadeComplete;
    }

    // Fade完成后的回调处理
    private void HandleFadeComplete(bool isIn)
    {
        // 只有淡出（isIn=false）完成时，才执行存档逻辑
        if (!isIn)
        {
            StartSaving();
        }
    }

    public static string ScreenShotName(int width, int height)
    {
        return string.Format("{0}/Saved Screenshots/SaveSlot{1} SavedGameSlot_{2}x{3}_{4}/SavedGameSlot_{1}x{2}_{3}.png",
            Application.persistentDataPath,
            countName,
            width, height, System.DateTime.Now.ToString("yyyy-MM-dd_HH-mm-ss"));
    }

    void Update()
    {
        if (Input.GetKeyDown("k"))
        {
            fader.StartFade(true, false);
        }
    }

    public void Save()
    {
        fader.StartFade(false, false);
    }

    public void StartSaving()
    {
        string filename = ScreenShotName(resWidth, resHeight);
        string directory = Path.GetDirectoryName(filename);
        Directory.CreateDirectory(directory);
        ScreenCapture.CaptureScreenshot(filename);
        string descriptionContent = _inputField.text;
        if (_inputField.text.Length != 0)
        {
            string descriptionFileFolder = directory + "\\" + "Description.txt";
            File.WriteAllText(descriptionFileFolder, descriptionContent);
        }
        StartCoroutine(saveLoad.SaveWithTime(directory, Path.GetFileNameWithoutExtension(filename) + ".savegame.txt"));

        countName++;
    }
}

逻辑说明

按下K键触发淡入，完成后回调收到isIn=true，不会触发存档
点击UI按钮调用Save触发淡出，协程结束后回调收到isIn=false，此时执行StartSaving，完美实现等待淡出完成再存档的需求
这种方式避免了静态变量的全局状态污染，逻辑清晰且不会出现提前触发的问题

内容的提问来源于stack exchange，提问作者Daniel Lip

如何判断Unity协程Fade的结束状态并正确触发存档逻辑？

原始Fader脚本 #

原始SavingGame脚本 #

解决方案：用回调/事件替代静态标志位 #

步骤1：修改Fader脚本 #

步骤2：修改SavingGame脚本 #