使用计算着色器将纹理转换为浮点值的一维数组

Question

我对计算着色器(通过Unity的DirectCompute(有一个相当简单的要求。我有一个 128x128 的纹理，我想将该纹理的红色通道转换为 1d 浮点数组。我需要经常这样做，所以只是在每个纹素上做一个 CPU 端的 for 循环不会削减它。

初始化：

m_outputBuffer = new ComputeBuffer(m_renderTexture.width * m_renderTexture.height, sizeof(float));
m_kernelIndex = m_computeShader.FindKernel("CSMain");

下面是 C# 方法：

/// <summary>
/// This method converts the red channel of the given RenderTexture to a
/// one dimensional array of floats of size width * height.
/// </summary>
private float[] ConvertToFloatArray(RenderTexture renderTexture)
{
m_computeShader.SetTexture(m_kernelIndex, INPUT_TEXTURE, renderTexture);
float[] result = new float[renderTexture.width * renderTexture.height];
m_outputBuffer.SetData(result);
m_computeShader.SetBuffer(m_kernelIndex, OUTPUT_BUFFER, m_outputBuffer);
m_computeShader.Dispatch(m_kernelIndex, renderTexture.width / 8, renderTexture.height / 8, 1);
m_outputBuffer.GetData(result);
return result;
}

和整个计算着色器：

// Each #kernel tells which function to compile; you can have many kernels
#pragma kernel CSMain
// Create a RenderTexture with enableRandomWrite flag and set it
// with cs.SetTexture
Texture2D<float4> InputTexture;
RWBuffer<float> OutputBuffer;
[numthreads(8, 8, 1)]
void CSMain(uint3 id : SV_DispatchThreadID)
{
OutputBuffer[id.x * id.y] = InputTexture[id.xy].r;
}

C# 方法返回预期大小的数组，它通常与我的预期相对应。但是，即使我的输入纹理是均匀的红色，仍然会有一些零。

Answer 1

我重新考虑并解决了我自己的问题。答案分为两部分：我奇怪地组合了x和y坐标(id.x和id.y(，并且使用了错误的输入语义。(SV_GroupThreadID而不是SV_DispatchThreadID(

所以这是解决方案。我还翻转了y轴以符合我的直觉。

// Each #kernel tells which function to compile; you can have many kernels
#pragma kernel CSMain
// Create a RenderTexture with enableRandomWrite flag and set it
// with cs.SetTexture
Texture2D<float4> InputTexture;
RWBuffer<float> OutputBuffer;
[numthreads(8, 8, 1)]
void CSMain(uint3 id : SV_DispatchThreadID)
{
uint w, h;
InputTexture.GetDimensions(w, h);
OutputBuffer[id.x + id.y * w] = InputTexture[float2(id.x, h - 1 - id.y)].r;
}