DispatchIndirect 和 Dispatch 有什么区别？

Question

Unity的

Dispatch

和

DispatchIndirect

有什么区别？

我多次尝试了解这一点，但都失败了。

我认为

DispatchIndirect

会导致着色器同时运行多次。

但事实并非如此。我现在真的不知道。

ps。下面的代码现在无法运行。

#pragma kernel CSMain

struct IndirectData
{
   uint numGroupX;
   uint numGroupY;
   uint numGroupZ;
   uint texIndex;
};

RWTexture2D<float4> renderTexture;
StructuredBuffer<Texture2D> texBuffer;
StructuredBuffer<IndirectData> dispatchData;

[numthreads(8, 8, 1)]
void CSMain(uint3 id : SV_DispatchThreadID)
{
   // some code...

   IndirectData data = dispatchData[**ShaderIndex**];  //I wanted this index value...
   renderTexture[id.xy] = texBuffer[data.texIndex];

   // some code...
}

C# 代码

// some code...

struct IndirectData
{
   public uint numGroupX;
   public uint numGroupY;
   public uint numGroupZ;
   public uint texIndex;
   // some code...
};

// some code...

IndirectData[] data = new IndirectData[orderCount];
void SomeFunc(out data);

// some code...

ComputeBuffer buffer = new ComputeBuffer(orderCount, Marshal.SizeOf(typeof(IndirectData)), ComputeBufferType.IndirectArguments);
buffer.SetData(data);
    
shader.SetBuffer(kernelID, rectID, buffer);
shader.DispatchIndirect(kernelID, buffer, 0);

// some code...

Answer 1

回答标题中的问题，根据我的经验，以下

ID3D11DeviceContext::Dispatch

电话，

context->Dispatch(x, y, z);

相当于使用以

DispatchIndirect

为内容的缓冲区调用

{x,y,z}

：

D3D11_BUFFER_DESC desc{};
desc.ByteWidth = sizeof(unsigned) * 3;
desc.MiscFlags = D3D11_RESOURCE_MISC_DRAWINDIRECT_ARGS;
ID3D11Buffer* argbuf;
unsigned dim[] = { x, y, z };
D3D11_SUBRESOURCE_DATA argdata{};
argdata.pSysMem = dim;
device->CreateBuffer(&desc, &argdata, &argbuf);
context->DispatchIndirect(argbuf, 0);