XNA视差背景不会显示所有图层

Question

Im playing around with the Platformer Starter Kit and so far I've added in horizontal and vertical "camera" movement and Im trying to add inn a parallaxing background. The problem is that after two background layers it stops showing the rest of them. Im very new to XNA and need a little help :). Heres a pic of the problem:

Heres the code. Please tell me if you need some more :)

Layer classes:

class Layer
 {
    public Texture2D[] Textures { get; private set; }
    public float ScrollRate { get; private set; }

    public Layer(ContentManager content, string basePath, float scrollRate)
    {
        // Assumes each layer only has 3 segments.
        Textures = new Texture2D[3];
        for (int i = 0; i < 3; ++i)
            Textures[i] = content.Load<Texture2D>(basePath + "_" + i);

        ScrollRate = scrollRate;
    }

    public void Draw(SpriteBatch spriteBatch, float cameraPosition, float cameraPositionYAxis)
    {
        // Assume each segment is the same width.
        int segmentWidth = Textures[0].Width;

        // Calculate which segments to draw and how much to offset them.
        float x = cameraPosition * ScrollRate;
        float y = ScrollRate;
        int leftSegment = (int)Math.Floor(x / segmentWidth);
        int rightSegment = leftSegment + 1;
        x = (x / segmentWidth - leftSegment) * -segmentWidth;

        spriteBatch.Draw(Textures[leftSegment % Textures.Length], new Vector2(x, -y), Color.White);
        spriteBatch.Draw(Textures[rightSegment % Textures.Length], new Vector2(x + segmentWidth, -y), Color.White);
    }


}

Heres the draw method in my Level.cs with my ScrollCamera (dont know if ScrollCamera has anything to do with it)

public void Draw(GameTime gameTime, SpriteBatch spriteBatch)
    {
        ScrollCamera(spriteBatch.GraphicsDevice.Viewport);
        Matrix cameraTransformYAxis = Matrix.CreateTranslation(-cameraPosition, -cameraPositionYAxis, 0.0f);
        spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, SamplerState.LinearClamp,
            DepthStencilState.Default, RasterizerState.CullCounterClockwise, null, cameraTransformYAxis);

        //added this foreach loop 
        foreach (var layer in layers)
        {
            layer.Draw(spriteBatch, cameraPosition, cameraPositionYAxis);
        }

        DrawTiles(spriteBatch);
        Player.Draw(gameTime, spriteBatch);
        foreach (Enemy enemy in enemies)
        {
            enemy.Draw(gameTime, spriteBatch);
        }

        spriteBatch.End();

    }

    private void ScrollCamera(Viewport viewport)
    {
        #if ZUNE
        const float ViewMargin = 0.4f;
        #else
        const float ViewMargin = 0.5f;
        #endif

        float marginWidth = viewport.Width * ViewMargin;
        float marginLeft = cameraPosition + marginWidth;
        float marginRight = cameraPosition + viewport.Width - marginWidth;


        const float TopMargin = 0.4f;
        const float BottomMargin = 0.4f;
        float marginTop = cameraPositionYAxis + viewport.Height * TopMargin;
        float marginBottom = cameraPositionYAxis + viewport.Height - viewport.Height * BottomMargin;
        //    float maxCameraPositionYOffset = Tile.Height * Height - viewport.Height; 


        float CameraMovement = 0.0f;
        if (Player.Position.X < marginLeft)
            CameraMovement = Player.Position.X - marginLeft;
        else if (Player.Position.X > marginRight)
            CameraMovement = Player.Position.X - marginRight;
        //Aktualizuj przesuwanie ekranu, ale zapobiegnij wyjściu poza mape
        float maxCameraPosition = Tile.Width * Width - viewport.Width;
        cameraPosition = MathHelper.Clamp(cameraPosition + CameraMovement, 0.0f, maxCameraPosition);



        float cameraMovementY = 0.0f;
        if (Player.Position.Y < marginTop) //above the top margin
            cameraMovementY = Player.Position.Y - marginTop;
        else if (Player.Position.Y > marginBottom) //below the bottom margin
            cameraMovementY = Player.Position.Y - marginBottom;

        float maxCameraPositionYOffset = Tile.Height * Height - viewport.Height;
        cameraPositionYAxis = MathHelper.Clamp(cameraPositionYAxis + cameraMovementY, 0.0f, maxCameraPositionYOffset);

    }

And I think thats it. Please tell me if you need some more code :)

Answer 1

You want to use Linear Wrapping. There's an excellent blog post on it right here. This assumes of course that your texture tiles perfect. You just simply need to to set your linear wrapping mode, code example below:

// Use this one instead!
spriteBatch.Begin(SpriteSortMode.Deferred, null, SamplerState.LinearWrap, null, null);
spriteBatch.Draw(texture, position, new Rectangle(-scrollX, -scrollY, texture.Width, texture.Height), Color.White);
spriteBatch.End();