MonoGame：模板缓冲区不起作用

Question

我正在尝试为基于MonoGame的2D游戏添加阴影。起初我只是为框架渲染了半透明的黑色纹理，但它们有时会重叠并且看起来很讨厌：

我首先尝试将所有阴影渲染到模板缓冲区中，然后使用单个半透明纹理使用模板缓冲区一次性绘制所有阴影。但是，它没有按预期工作：

这两个问题是：

• 阴影渲染到场景中
• 模板缓冲区看似不受影响：半透明黑色纹理覆盖整个屏幕

这是初始化代码：

StencilCreator = new DepthStencilState
{
    StencilEnable = true,
    StencilFunction = CompareFunction.Always,
    StencilPass = StencilOperation.Replace,
    ReferenceStencil = 1
};

StencilRenderer = new DepthStencilState
{
    StencilEnable = true,
    StencilFunction = CompareFunction.Equal,
    ReferenceStencil = 1,
    StencilPass = StencilOperation.Keep
};

var projection = Matrix.CreateOrthographicOffCenter(0, GraphicsDevice.Viewport.Width, GraphicsDevice.Viewport.Height, 0, 0, 1); 
var halfPixel = Matrix.CreateTranslation(-0.5f, -0.5f, 0);

AlphaEffect = new AlphaTestEffect(GraphicsDevice)
{
    DiffuseColor = Color.White.ToVector3(),
    AlphaFunction = CompareFunction.Greater,
    ReferenceAlpha = 0,
    World = Matrix.Identity,
    View = Matrix.Identity,
    Projection = halfPixel * projection
};

MaskingTexture = new Texture2D(GameEngine.GraphicsDevice, 1, 1);
MaskingTexture.SetData(new[] { new Color(0f, 0f, 0f, 0.3f) });

ShadowTexture = ResourceCache.Get<Texture2D>("Skins/Common/wall-shadow");

以下代码是我Draw方法的主体：

// create stencil
GraphicsDevice.Clear(ClearOptions.Stencil, Color.Black, 0f, 0);
var batch = new SpriteBatch(GraphicsDevice);
batch.Begin(SpriteSortMode.Immediate, null, null, StencilCreator, null, AlphaEffect);
foreach (Vector2 loc in ShadowLocations)
{
    newBatch.Draw(
        ShadowTexture,
        loc,
        null,
        Color.White,
        0f,
        Vector2.Zero,
        2f,
        SpriteEffects.None,
        0f
    );
}
batch.End();

// render shadow texture through stencil
batch.Begin(SpriteSortMode.Immediate, null, null, StencilRenderer, null);
batch.Draw(MaskingTexture, GraphicsDevice.Viewport.Bounds, Color.White);
batch.End();

可能是什么问题？相同的代码在我的XNA项目中运行良好。

Answer 1

我使用RenderTarget2D而不是模板缓冲区解决了这个问题。将纯黑色阴影绘制到RT2D，然后将RT2D本身绘制成具有半透明颜色的场景，可以实现并简化实现。