c# - 加载关卡后声音无法播放

Question

如果我只是告诉歌曲在整个菜单和第一级中播放(即一直如此)，那么它的播放就很好。但是，我希望声音仅在播放器按Enter并加载1级时播放。

相关代码在这里:

protected override void LoadContent()
{
    // Create a new SpriteBatch, which can be used to draw textures.
    spriteBatch = new SpriteBatch(GraphicsDevice);

    // Opening Screen Textures
    test = Content.Load<Texture2D>("test");

    // Load sounds here
    if (gameState == GameState.Level1)
    {
        backgroundSong = Content.Load<SoundEffect>("Call to Adventure");
        SoundEffectInstance backgroundSongInstance = backgroundSong.CreateInstance();
        backgroundSongInstance.IsLooped = true;
        backgroundSong.Play();
    }
}

就像我说的那样，在进行if循环之前，声音播放得很好。知道我在做什么错吗？当用户按下Enter键时，游戏从 gameState.Menu变为 gameState.Level1(图形加载，声音除外，一切正常)。

完整的代码在这里，以防万一我错过了上面的任何内容:

public class Game1 : Microsoft.Xna.Framework.Game
{
    GraphicsDeviceManager graphics;
    SpriteBatch spriteBatch;
    const int WINDOW_WIDTH = 800;
    const int WINDOW_HEIGHT = 600;

    // game state
    GameState gameState = GameState.OpeningMenu;

    // menu fields
    Texture2D test;

    // Level 1 textures list
    Texture2D skyBackground;
    //Texture2D dirtTexture;
    Texture2D grassTexture;
    Texture2D leftGrassTexture;
    Texture2D rightGrassTexture;

    // sounds
    SoundEffect backgroundSong;

    // Level 1 platforms
    Platforms platform1;
    Platforms platform2;
    Platforms platform3;
    Platforms platform4;
    Platforms platform5;
    Platforms platform6;
    Platforms platform7;
    Platforms platform8;
    Platforms platform9;

    // drawing variables
    int oneWidthUnit = WINDOW_WIDTH / 40;
    int oneHeightUnit = WINDOW_HEIGHT / 30;
    //int twoWidthUnits = WINDOW_WIDTH / 20;
    //int twoHeightUnits = WINDOW_HEIGHT / 15;

    public Game1()
    {
        graphics = new GraphicsDeviceManager(this);
        Content.RootDirectory = "Content";

        graphics.PreferredBackBufferWidth = WINDOW_WIDTH;
        graphics.PreferredBackBufferHeight = WINDOW_HEIGHT;
        IsMouseVisible = true;
    }

    protected override void Initialize()
    {
        Window.Title = "Rory's Super Mega Awesome Game of Awesomeness";
        base.Initialize();
    }

    protected override void LoadContent()
    {
        // Create a new SpriteBatch, which can be used to draw textures.
        spriteBatch = new SpriteBatch(GraphicsDevice);

        // Opening Screen Textures
        test = Content.Load<Texture2D>("test");

        // Load sounds here
        if (gameState == GameState.Play)
        {
            backgroundSong = Content.Load<SoundEffect>("Call to Adventure");
            SoundEffectInstance backgroundSongInstance = backgroundSong.CreateInstance();
            backgroundSongInstance.IsLooped = true;
            backgroundSong.Play();
        }

        // Load Level 1 sprite textures here
        skyBackground = Content.Load<Texture2D>("skybackground");
        //dirtTexture = Content.Load<Texture2D>("dirt");
        grassTexture = Content.Load<Texture2D>("grass_top");
        leftGrassTexture = Content.Load<Texture2D>("edge_left");
        rightGrassTexture = Content.Load<Texture2D>("edge_right");

        //create platforms
        platform1 = new Platforms(0, 28 * oneHeightUnit, 15, grassTexture, leftGrassTexture, rightGrassTexture);
        platform2 = new Platforms(26 * oneWidthUnit, 28 * oneHeightUnit, 14, grassTexture, leftGrassTexture, rightGrassTexture);
        platform3 = new Platforms(10 * oneWidthUnit, 23 * oneHeightUnit, 7, grassTexture, leftGrassTexture, rightGrassTexture);
        platform4 = new Platforms(18 * oneWidthUnit, 19 * oneHeightUnit, 5, grassTexture, leftGrassTexture, rightGrassTexture);
        platform5 = new Platforms(5 * oneWidthUnit, 15 * oneHeightUnit, 9, grassTexture, leftGrassTexture, rightGrassTexture);
        platform6 = new Platforms(19 * oneWidthUnit, 11 * oneHeightUnit, 3, grassTexture, leftGrassTexture, rightGrassTexture);
        platform7 = new Platforms(23 * oneWidthUnit, 7 * oneHeightUnit, 3, grassTexture, leftGrassTexture, rightGrassTexture);
        platform8 = new Platforms(30 * oneWidthUnit, 7 * oneHeightUnit, 7, grassTexture, leftGrassTexture, rightGrassTexture);
        platform9 = new Platforms(34 * oneWidthUnit, 14 * oneHeightUnit, 6, grassTexture, leftGrassTexture, rightGrassTexture);

    }

    protected override void Update(GameTime gameTime)
    {
        // goes from menu to level 1 when player presses enter
        if (gameState == GameState.OpeningMenu && Keyboard.GetState().IsKeyDown(Keys.Enter))
        {
            gameState = GameState.Play;
        }

        base.Update(gameTime);
    }

    protected override void Draw(GameTime gameTime)
    {
        GraphicsDevice.Clear(Color.CornflowerBlue);

        spriteBatch.Begin();

        // draw opening menu
        if (gameState == GameState.OpeningMenu)
        {
            Rectangle rec = new Rectangle(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
            spriteBatch.Draw(test, rec, Color.White);
        }

        // draw level 1
        else if (gameState == GameState.Play)
        {
            DrawScenery();

            platform1.Draw(spriteBatch);
            platform2.Draw(spriteBatch);
            platform3.Draw(spriteBatch);
            platform4.Draw(spriteBatch);
            platform5.Draw(spriteBatch);
            platform6.Draw(spriteBatch);
            platform7.Draw(spriteBatch);
            platform8.Draw(spriteBatch);
            platform9.Draw(spriteBatch);
        }

        spriteBatch.End();

        base.Draw(gameTime);
    }

    #region Drawing Code

    // draw the sky
    private void DrawScenery()
    {
        Rectangle backgroundRectangle = new Rectangle(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
        spriteBatch.Draw(skyBackground, backgroundRectangle, Color.White);
    }

    #endregion
}

Answer 1

LoadContent通常被调用一次以加载您的内容，而Update()每秒被调用约60次(视情况而定)。您用于检测跳跃的代码很好，并且看起来您希望更改游戏状态时会执行LoadContent中的代码。事实并非如此，代码无法知道您要执行此操作(可以创建事件处理程序)。您可能应该创建一个类似于PlaySounds()的方法，并且(以前)在加载游戏/关卡时会调用它。现在，当您按Enter键时，它将调用它

您也应该继续加载所有需要的内容，因为您不会再返回LoadContent()了。

protected override void LoadContent()
{
    // Create a new SpriteBatch, which can be used to draw textures.
    spriteBatch = new SpriteBatch(GraphicsDevice);

    // Opening Screen Textures
    test = Content.Load<Texture2D>("test");

    //LOAD but DONT PLAY sound
    backgroundSong = Content.Load<SoundEffect>("Call to Adventure");
    backgroundSongInstance = backgroundSong.CreateInstance();
    backgroundSongInstance.IsLooped = true;

    //Rest of code cut out for example!
}

继续将 SoundEffectInstance backgroundSongInstance设为一个新变量，这样您就可以对其进行更多控制(因为它会退出 Update()方法的作用域而被销毁，因此我们以后可以访问它。

在 Update方法中:

 //Goes from menu to level 1 when player presses enter
 if (gameState == GameState.OpeningMenu && Keyboard.GetState().IsKeyDown(Keys.Enter))
 {
      gameState = GameState.Play;
      //Start playing sound
      backgroundSongInstance.Play();
 }