Graphics 为什么这128位颜色格式被转换成32位

我正在尝试为我正在进行的项目编写HLSL像素着色器。基本上我想做的是，如果一个纹理有一个浮动值为0.52的像素，在0-255的范围内是132.6，我想输出133 60%的时间，输出132 40%的时间。现在写，我只是想输出RGB值的分数余数，也就是说，有机会将像素放大，但是我总是得到一个0的值，我想这是因为颜色在到达着色器之前被量化到0-255的比例，但我不知道为什么会这样，因为我使用的是A32B32G32R32f格式，它应该能够存储有关颜色的大量信息。这是我非常简单的着色器代码。我正在使用SlimDX DX9，如果这很重要的话

sampler2D Tex0 : register(s0);
float4 DitherByChance(float2 coords : TEXCOORD0) : COLOR
{
    float4 newColor = float4(0, 0, 0, 0);   // The pixel color to return
    double4 oldColor = tex2D(Tex0, coords);
    double scale = 0.0039215686274509803921568627451;  // 1 / 255

    double rPercentChance = frac(oldColor.r / scale);   //Chance to round red channel up
    double gPercentChance = frac(oldColor.g / scale);   //Chance to round green channel up
    double bPercentChance = frac(oldColor.b / scale);   //Chance to round blue channel up

    newColor.r = rPercentChance;
    newColor.g = gPercentChance;
    newColor.b = bPercentChance;

    newColor.a = 1;

    return newColor;
}

technique DitherViaChance  
{  
    pass Pass1  
    {  
        PixelShader = compile ps_2_0 DitherByChance();      
    }  
}

以下是我的slimDX代码（如果有关系）：

Public Class TextStimulusDisplay
    Inherits BaseStimulusDisplay

    Protected ditherByChanceEffect As PixelShader
    Protected psByteCode As ShaderBytecode
    Protected gStream As DataStream
    Protected ditherBC As Effect

    Protected tex As Texture
    Protected spriteRender As Sprite

    Public displaySettings As DisplaySettings
    Public charText As Texture
    Public randomText As Texture

    Protected rando As Random

    Public Sub New(ByVal displaysettings As DisplaySettings, Optional ByVal WindowedMode As Boolean = False)
        MyBase.New(New Size(displaysettings.xResolution, displaysettings.yResolution), WindowedMode)
        Me.displaySettings = displaysettings
    End Sub

    Public Overrides Sub CreateDeviceResources()
        MyBase.CreateDeviceResources()
        ditherBC = Effect.FromFile(device, Application.StartupPath & "\effects\DitherByChance.fx", ShaderFlags.Debug)
        rando = New Random()

        randomText = New Texture(device, 100, 100, 1, Usage.Dynamic, Format.A32B32G32R32F, Pool.Default)
        Dim data(80000) As Byte
        rando.NextBytes(data)
        Dim dataBox As DataRectangle = randomText.GetSurfaceLevel(0).LockRectangle(LockFlags.None)
        dataBox.Data.Seek(0, IO.SeekOrigin.Begin)
        dataBox.Data.Write(data, 0, data.Length)
        dataBox.Data.Close()
        randomText.GetSurfaceLevel(0).UnlockRectangle()

        device.SetTexture(1, randomText)

        'psByteCode = ShaderBytecode.CompileFromFile(Application.StartupPath & "\effects\DitherByChance.fx", "DitherByChance", "ps_2_0", ShaderFlags.None)
        'ditherByChanceEffect = New PixelShader(device, psByteCode)
        'device.PixelShader = ditherByChanceEffect
        spriteRender = New Sprite(device)
        spriteRender.Transform = Matrix.Identity
        tex = createCharacterTexture()

    End Sub

    Public Overrides Sub ReleaseDeviceResources()
        MyBase.ReleaseDeviceResources()
    End Sub

    Public Overrides Sub RenderScene()
        'ditherBC.Technique = ditherBC.GetTechnique("DitherViaChance")

        Me.device.BeginScene()
        spriteRender.Begin(SpriteFlags.None)
        ditherBC.Begin()
        ditherBC.BeginPass(0)
        spriteRender.Draw(tex, New Rectangle(0, 0, 50, 50), New Color4(1, 1, 1))
        'spriteRender.Draw(randomText, New Rectangle(0, 0, 1000, 1000), New Color4(1, 1, 1))
        spriteRender.End()
        ditherBC.EndPass()
        ditherBC.End()
        Me.device.EndScene()
    End Sub

    Public Function createCharacterTexture() As Texture
        Dim RtsHelper As RenderToSurface = New RenderToSurface(device, 100, 100, Format.A32B32G32R32F)
        Dim texture As Texture = New Texture(device, 100, 100, 1, Usage.RenderTarget, Format.A32B32G32R32F, Pool.Default)

        Dim sloanFont As Font = New Font(device, 98, 98, FontWeight.Normal, 1, False, CharacterSet.Default, Precision.Default,
                                         FontQuality.ClearTypeNatural, PitchAndFamily.Default, "Sloan")


        RtsHelper.BeginScene(texture.GetSurfaceLevel(0), New Viewport(0, 0, 100, 100))



        sloanFont.DrawString(Nothing, "A", 1, 1, New SlimDX.Color4())
        RtsHelper.EndScene(Filter.None)

        Font.Dispose()
        RtsHelper.Dispose()

        Return texture
    End Function
End Class

---

这是很多代码。。尽管我没读过。。有一件事。。您是说128位转换为32位可能是数据类型问题您使用什么数据类型来存储颜色？您是否尝试将其存储在float中？我已尝试将其存储在多种不同的纹理格式中。在我上面发布的代码中，查看createCharacterTexture方法。我创建了一个A32B32G32R32f格式的纹理，这意味着每个ARGB颜色通道都获得32位浮点值来存储颜色信息。但是，当我在renderScene方法中将该纹理绘制到屏幕上时，我的HLSL效果代码只会看到已量化到255个级别的浮动，每个通道8位。我不明白为什么？我也试过A16 R16 G16 B16 f、A16 R16 G16 B16 B16和A2 R10 G10 B10，但似乎都不起作用。您的采样情况如何？128位像素的采样可能需要在最接近模式下进行-采样单元不能进行全浮点运算，因此无法在双线性模式下正确采样。嗯。。。我不知道我是如何做的采样，我想这是什么样的结果。我该如何改变这一点？是在HLSL代码中，我声明必须以某种方式设置2Dsampler吗？它不应该在HLSL代码中-我想应该是在SlimDX代码中设置纹理的地方。不幸的是，我不知道SlimDX。。。