Question

我想要实现的目标如下：我的传递将返回一个巨大的数组，其中包含一些重复的重复数字，我需要在CPU上检索和处理。

我尝试渲染成2000x1纹理，然后使用RenderTarget2d.GetData＆lt;＆gt;（）和foreach循环在CPU上对其进行采样。它非常慢:)。所以我回避了我的问题，现在的想法是多次渲染到1x1纹理。在中间传递中，我将在我的着色器中扩展一个参数数组，以包含已经返回的数字。每个像素将查询数组并剪辑自身，如果它包含已经出现的数字。

现在的问题是像素颜色永远不会改变我渲染的颜色 - 它总是返回一些随机数。当我在绘制调用之前添加Game.GraphicsDevice.Clear(Color.Transparent);时，它开始返回零，尽管着色器代码应返回0.2f（或其0到255等效值）。可能是因为我在其中渲染的内容太小（我在屏幕上绘制一条线并沿着线条对场景的颜色进行采样）并在某个时刻进行了渲染？

C＃/ XNA代码：

                            CollisionRT = new RenderTarget2D(Game.GraphicsDevice, 1, 1, false, SurfaceFormat.Color, DepthFormat.None);

...             
                Game.GraphicsDevice.BlendState = BlendState.AlphaBlend;
                Game.GraphicsDevice.SetRenderTarget(CollisionRT);
                Game.GraphicsDevice.Clear(Color.Transparent);
                Game.GraphicsDevice.DepthStencilState = DepthStencilState.None;

                foreach (ModelMesh mesh in PPCBulletInvis.Model.Meshes)
                    // PPCBulletInvis is a line that covers 1/18 of the screen (approx).
                {
                    foreach (Effect effect in mesh.Effects)
                    {
                        //effect.Parameters["Texture"].SetValue(vfTex);
                        effect.Parameters["halfPixel"].SetValue(halfPixel);
                        effect.Parameters["sceneMap"].SetValue(sceneRT);
                        effect.Parameters["World"].SetValue(testVWall.World);
                        effect.Parameters["View"].SetValue(camera.View);
                        effect.Parameters["Projection"].SetValue(camera.Projection);
                    }
                    mesh.Draw();
                }

                Game.GraphicsDevice.SetRenderTarget(null);

                Rectangle sourceRectangle =
                    new Rectangle(0, 0, 1, 1);

                Color[] retrievedColor = new Color[1];
                CollisionRT.GetData<Color>(retrievedColor);

                Console.WriteLine(retrievedColor[0].R); // Returns zeroes.

着色器代码：

float4x4 World;
float4x4 View;
float4x4 Projection;

texture sceneMap;
sampler sceneSampler = sampler_state
{
    Texture = (sceneMap);
    AddressU = CLAMP;
    AddressV = CLAMP;
    MagFilter = POINT;
    MinFilter = POINT;
    Mipfilter = POINT;
};

float2 halfPixel;

struct VS_INPUT
{
    float4 Position     : POSITION0;
};
struct VS_OUTPUT
{
    float4 Position         : POSITION0;
    float4 ScreenPosition   : TEXCOORD2;
};


VS_OUTPUT VertexShaderFunction(VS_INPUT input)
{
    VS_OUTPUT output;

    float4 worldPosition = mul(input.Position, World);
    float4 viewPosition = mul(worldPosition, View);
    output.Position = mul(viewPosition, Projection);

    output.ScreenPosition = output.Position;
    return output;
}

float4 PixelShaderFunction(VS_OUTPUT input) : COLOR0
{
    input.ScreenPosition.xy /= input.ScreenPosition.w;

    float2 screenTexCoord = 0.5f * (float2(input.ScreenPosition.x,-input.ScreenPosition.y) + 1);

    screenTexCoord -=halfPixel;

    return (0.2f,0.2f,0.2f,0.2f);//tex2D(sceneSampler, screenTexCoord);
}

technique Technique1
{
    pass Pass1
    {
        VertexShader = compile vs_3_0 VertexShaderFunction();
        PixelShader = compile ps_3_0 PixelShaderFunction();
    }
}

将线渲染为1x1 RenderTarget2D不会更改目标的像素颜色

0 个答案: