c# - XNA-名称“ball”在当前上下文中不存在

由于我是XNA的新手，所以我正在从事乒乓球游戏，但遇到了问题...
我有3个课，分别是"Game1.cs"，"Ball.cs"和"GreenPaddle.cs"。

GreenPaddle.cs包含Rectangle gpRect，Texture2D gPtexture，Vector2 position。

我有运动之类的东西，在球类中我有一个相交的布尔值。
但是，当我尝试在game1.cs中初始化它时，会出现错误。这些是类：

GreenPaddle.cs：

public class GreenPaddle
{
    Texture2D gPtexture;
    public Vector2 position;
    public Rectangle gpRect;
    public Vector2 origin;
    public int speed = 2;

    public GreenPaddle()
    {

    }

    public void LoadContent(ContentManager Content)
    {
        gPtexture = Content.Load<Texture2D>("greenpaddle");
        position = new Vector2(20, 200);
        gpRect = new Rectangle((int)position.X, (int)position.Y,
            gPtexture.Width, gPtexture.Height);
    }

    public void Update(GameTime gameTime)
    {
        KeyboardState keyState = Keyboard.GetState();

        //Movement
        PaddleMovement();

        //Border Collision
        isCollidingWithBorders();
      }

    public void Draw(SpriteBatch spriteBatch)
    {
        spriteBatch.Draw(gPtexture, position, gpRect, Color.LawnGreen);
    }
    public Boolean isCollidingWithBorders()
    {
        if (position.Y < 83 && gpRect.Y < 83)
        {
            position.Y = 83;
            gpRect.Y = 83;
            return true;
        }

        if (position.Y > 400 && gpRect.Y > 400)
        {
            position.Y = 400;
            gpRect.Y = 400;
            return true;
        }

        else { return false; }

    }

    public void PaddleMovement()
    {
        KeyboardState keyState = Keyboard.GetState();
        if (keyState.IsKeyDown(Keys.W))
        {
            position.Y -= speed;
            gpRect.Y -= speed;
        }
        if (keyState.IsKeyDown(Keys.S))
        {
            position.Y += speed;
            gpRect.Y += speed;
        }
    }
}

Ball.cs：

public class Ball
{
    GreenPaddle gPaddle;


    Texture2D ballTexture;
    Vector2 ballPosition;
    Rectangle ballRect;
    int speed = 2;
    bool movingUp, movingLeft;

    public Ball(GreenPaddle paddle)
    {
        this.gPaddle = paddle;
        movingLeft = true;
        movingUp = true;
    }

    public void LoadContent(ContentManager Content)
    {
        ballTexture = Content.Load<Texture2D>("ball");
        ballPosition = new Vector2(380, 225);
        ballRect = new Rectangle((int)ballPosition.X, (int)ballPosition.Y,
            ballTexture.Width, ballTexture.Height);

    }

    public void Update(GameTime gameTime)
    {
        BallMovement();

    }

    public void Draw(SpriteBatch spriteBatch)
    {
        spriteBatch.Draw(ballTexture, ballPosition, ballRect, Color.White);
    }

    public void BallMovement()
    {
        if (movingUp) { ballPosition.Y -= speed; }
        if (!movingUp) { ballPosition.Y += speed; }
        if (movingLeft) { ballPosition.X -= speed; }
        if (!movingLeft) { ballPosition.X += speed; }

        if (ballRect.Intersects(gPaddle.gpRect))
            movingLeft = !movingLeft;
                movingUp = !movingUp;

        if (ballPosition.Y < 85)
        {
            movingUp = false;
        }
    }
}

Game1.cs：

 public class Game1 : Microsoft.Xna.Framework.Game
{
    GraphicsDeviceManager graphics;
    SpriteBatch spriteBatch;

    GreenPaddle gPaddle = new GreenPaddle();


    Texture2D BackGround;

    public Game1()
    {
        graphics = new GraphicsDeviceManager(this);
        Content.RootDirectory = "Content";
        graphics.PreferredBackBufferHeight = 500;
    }

    protected override void Initialize()
    {

    Ball ball = new Ball(gPaddle);
        base.Initialize();
    }

    /// <summary>
    /// LoadContent will be called once per game and is the place to load
    /// all of your content.
    /// </summary>
    protected override void LoadContent()
    {
        // Create a new SpriteBatch, which can be used to draw textures.
        spriteBatch = new SpriteBatch(GraphicsDevice);

        BackGround = Content.Load<Texture2D>("pongBG");
        gPaddle.LoadContent(Content);
        //ball.LoadContent(Content);
    }

    /// <summary>
    /// UnloadContent will be called once per game and is the place to unload
    /// all content.
    /// </summary>
    protected override void UnloadContent()
    {
        // TODO: Unload any non ContentManager content here
    }

    /// <summary>
    /// Allows the game to run logic such as updating the world,
    /// checking for collisions, gathering input, and playing audio.
    /// </summary>
    /// <param name="gameTime">Provides a snapshot of timing values.</param>
    protected override void Update(GameTime gameTime)
    {
        // Allows the game to exit
        if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
            this.Exit();

        gPaddle.Update(gameTime);
        ball.Update(gameTime);//Error Line

        base.Update(gameTime);
    }

    /// <summary>
    /// This is called when the game should draw itself.
    /// </summary>
    /// <param name="gameTime">Provides a snapshot of timing values.</param>
    protected override void Draw(GameTime gameTime)
    {
        GraphicsDevice.Clear(Color.CornflowerBlue);

        spriteBatch.Begin();
        spriteBatch.Draw(BackGround, new Vector2(0f, 0f), Color.White);
        gPaddle.Draw(spriteBatch);
        ball.Draw(spriteBatch);//Error Line
        spriteBatch.End();

        base.Draw(gameTime);
    }
}

就是这样，我不知道如何处理初始化部分：/

最佳答案

仔细查看如何初始化球，并在方法范围内（在花括号之间）声明它。这意味着您无法在其他任何地方访问它，这是您尝试在Update和Draw方法中进行的。

protected override void Initialize()
{
    Ball ball = new Ball(gPaddle);
    base.Initialize();
}

此外，函数结束后，您的Ball对象也会被删除。

可以通过将Ball ball放入类范围来解决此问题，以便类的所有成员都可以使用它，如下所示：

Ball ball;  //In the class scope

protected override void Initialize()
{
    ball = new Ball(gPaddle);
    base.Initialize();
}

如果您不熟悉范围，请查看this文章（在MSDN上没有什么好用的）

关于c# - XNA-名称“ball”在当前上下文中不存在，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/17897370/