XNA 精灵旋转

我正在尝试在这里旋转代码中的"golf_ball"精灵，但我遇到了很多困难。我已经查看了教程，但没有运气。我的比赛基本上应该尽可能长时间地使用球拍将球保持在空中。任何帮助将不胜感激！

    public class Game1 : Microsoft.Xna.Framework.Game
{
    GraphicsDeviceManager graphics;
    SpriteBatch spriteBatch;
    // Ball sprite
    Texture2D ballSprite;
    // Ball location
    Vector2 ballPosition = Vector2.Zero;
    // Store some information about the sprite's motion.
    Vector2 ballSpeed = new Vector2(150, 150);
    // Paddle sprite
    Texture2D paddleSprite;
    // Paddle location
    Vector2 paddlePosition;
    public Game1()
    {
        graphics = new GraphicsDeviceManager(this);
        Content.RootDirectory = "Content";
    }
    /// <summary>
    /// Allows the game to perform any initialization it needs to before starting to run.
    /// This is where it can query for any required services and load any non-graphic
    /// related content.  Calling base.Initialize will enumerate through any components
    /// and initialize them as well.
    /// </summary>
    protected override void Initialize()
    {
        base.Initialize();
        // Set the initial paddle location
        paddlePosition = new Vector2(
            graphics.GraphicsDevice.Viewport.Width / 2 - paddleSprite.Width / 2,
            graphics.GraphicsDevice.Viewport.Height - paddleSprite.Height);
    }

    /// <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);
        ballSprite = Content.Load<Texture2D>("golf_ball");
        paddleSprite = Content.Load<Texture2D>("Paddle");
        // TODO: use this.Content to load your game content here
    }
    /// <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();
        // Move the sprite by speed, scaled by elapsed time
        ballPosition += ballSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
        int maxX = GraphicsDevice.Viewport.Width - ballSprite.Width;
        int maxY = GraphicsDevice.Viewport.Height - ballSprite.Height;
        // Check for bounce
        if (ballPosition.X > maxX || ballPosition.X < 0)
            ballSpeed.X *= -1;
        if (ballPosition.Y < 0)
            ballSpeed.Y *= -1;
        else if (ballPosition.Y > maxY)
        {
            // Ball hit the bottom of the screen, so reset ball
            ballPosition.Y = 0;
            ballSpeed.X = 150;
            ballSpeed.Y = 150;
        }

        // Ball and paddle collide?  Check rectangle intersection between objects
        Rectangle ballRect =
            new Rectangle((int)ballPosition.X, (int)ballPosition.Y,
            ballSprite.Width, ballSprite.Height);
        Rectangle handRect =
            new Rectangle((int)paddlePosition.X, (int)paddlePosition.Y,
                paddleSprite.Width, paddleSprite.Height);
        if (ballRect.Intersects(handRect))
        {
            // Increase ball speed
            ballSpeed.Y += 50;
            if (ballSpeed.X < 0)
                ballSpeed.X -= 50;
            else
                ballSpeed.X += 50;
            // Send ball back up the screen
            ballSpeed.Y *= -1;
        }
        base.Update(gameTime);
        // Update the paddle's position
        KeyboardState keyState = Keyboard.GetState();
        if (keyState.IsKeyDown(Keys.Right))
            paddlePosition.X += 5;
        else if (keyState.IsKeyDown(Keys.Left))
            paddlePosition.X -= 5;
    }

    /// <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);
        // Draw the sprite
        spriteBatch.Begin();
        spriteBatch.Draw(ballSprite, ballPosition, Color.White);
        spriteBatch.Draw(paddleSprite, paddlePosition, Color.White);
        spriteBatch.End();
        base.Draw(gameTime);
    }
}

}