DX11 computer shader例子

例子见：Microsoft DirectX SDK basic compute11

shader代码：

1. ```
   struct BufType
   {
   int i;
   float f;
   };

StructuredBuffer Buffer0 : register(t0);
StructuredBuffer Buffer1 : register(t1);
RWStructuredBuffer BufferOut : register(u0);

[numthreads(1, 1, 1)]
void CSMain( uint3 DTid : SV_DispatchThreadID )
{
BufferOut[DTid.x].i = Buffer0[DTid.x].i + Buffer1[DTid.x].i;
BufferOut[DTid.x].f = Buffer0[DTid.x].f + Buffer1[DTid.x].f;
}

c++代码：

// 构造并初始化Buffer0和Buffer1; g_vBuf0和g_vBuf1为BufType数组，数量为Num_Elements = 1024
CreateStructuredBuffer( g_pDevice, sizeof(BufType), NUM_ELEMENTS, &g_vBuf0[0], &g_pBuf0 );
CreateStructuredBuffer( g_pDevice, sizeof(BufType), NUM_ELEMENTS, &g_vBuf1[0], &g_pBuf1 );
CreateStructuredBuffer( g_pDevice, sizeof(BufType), NUM_ELEMENTS, NULL, &g_pBufResult );
// 构造ShaderResourceView作为input buffer， UnorderedAccessView作为outputBuffer
printf( "Creating buffer views..." );
CreateBufferSRV( g_pDevice, g_pBuf0, &g_pBuf0SRV );
CreateBufferSRV( g_pDevice, g_pBuf1, &g_pBuf1SRV );
CreateBufferUAV( g_pDevice, g_pBufResult, &g_pBufResultUAV );
// 设置deviceContext具体状态：g_pCS为computeShader指针
printf( "Running Compute Shader..." );
ID3D11ShaderResourceView aRViews[2] = { g_pBuf0SRV, g_pBuf1SRV };
RunComputeShader( g_pContext, g_pCS, 2, aRViews, NULL, NULL, 0, g_pBufResultUAV, NUM_ELEMENTS, 1, 1 );
// 子函数
//--------------------------------------------------------------------------------------
// Create Structured Buffer
//--------------------------------------------------------------------------------------
HRESULT CreateStructuredBuffer( ID3D11Device pDevice, UINT uElementSize, UINT uCount, VOID pInitData, ID3D11Buffer ppBufOut ) {
ppBufOut = NULL;

    D3D11_BUFFER_DESC desc;
    ZeroMemory( &desc, sizeof(desc) );
    desc.BindFlags = D3D11_BIND_UNORDERED_ACCESS | D3D11_BIND_SHADER_RESOURCE;
    desc.ByteWidth = uElementSize * uCount;
    desc.MiscFlags = D3D11_RESOURCE_MISC_BUFFER_STRUCTURED;
    desc.StructureByteStride = uElementSize;

    if ( pInitData )    {
        D3D11_SUBRESOURCE_DATA InitData;
        InitData.pSysMem = pInitData;
        return pDevice->CreateBuffer( &desc, &InitData, ppBufOut );
    } else
        return pDevice->CreateBuffer( &desc, NULL, ppBufOut );
}
//--------------------------------------------------------------------------------------
// Create Shader Resource View for Structured or Raw Buffers
//--------------------------------------------------------------------------------------
HRESULT CreateBufferSRV( ID3D11Device* pDevice, ID3D11Buffer* pBuffer, ID3D11ShaderResourceView** ppSRVOut ) {
    D3D11_BUFFER_DESC descBuf;
    ZeroMemory( &descBuf, sizeof(descBuf) );
    pBuffer->GetDesc( &descBuf );

    D3D11_SHADER_RESOURCE_VIEW_DESC desc;
    ZeroMemory( &desc, sizeof(desc) );
    desc.ViewDimension = D3D11_SRV_DIMENSION_BUFFEREX;
    desc.BufferEx.FirstElement = 0;

    if ( descBuf.MiscFlags & D3D11_RESOURCE_MISC_BUFFER_STRUCTURED )    {
        // This is a Structured Buffer

        desc.Format = DXGI_FORMAT_UNKNOWN;
        desc.BufferEx.NumElements = descBuf.ByteWidth / descBuf.StructureByteStride;
    } else    {
        return E_INVALIDARG;
    }

    return pDevice->CreateShaderResourceView( pBuffer, &desc, ppSRVOut );
}
//--------------------------------------------------------------------------------------
// Create Unordered Access View for Structured or Raw Buffers
//--------------------------------------------------------------------------------------
HRESULT CreateBufferUAV( ID3D11Device* pDevice, ID3D11Buffer* pBuffer, ID3D11UnorderedAccessView** ppUAVOut ) {
    D3D11_BUFFER_DESC descBuf;
    ZeroMemory( &descBuf, sizeof(descBuf) );
    pBuffer->GetDesc( &descBuf );

    D3D11_UNORDERED_ACCESS_VIEW_DESC desc;
    ZeroMemory( &desc, sizeof(desc) );
    desc.ViewDimension = D3D11_UAV_DIMENSION_BUFFER;
    desc.Buffer.FirstElement = 0;

    if ( descBuf.MiscFlags & D3D11_RESOURCE_MISC_BUFFER_STRUCTURED )    {
        // This is a Structured Buffer
        desc.Format = DXGI_FORMAT_UNKNOWN;      // Format must be must be DXGI_FORMAT_UNKNOWN, when creating a View of a Structured Buffer
        desc.Buffer.NumElements = descBuf.ByteWidth / descBuf.StructureByteStride;
    } else    {
        return E_INVALIDARG;
    }

    return pDevice->CreateUnorderedAccessView( pBuffer, &desc, ppUAVOut );
}
//--------------------------------------------------------------------------------------
// Run CS
//--------------------------------------------------------------------------------------
void RunComputeShader( ID3D11DeviceContext* pd3dImmediateContext,
                      ID3D11ComputeShader* pComputeShader,
                      UINT nNumViews, ID3D11ShaderResourceView** pShaderResourceViews,
                      ID3D11Buffer* pCBCS, void* pCSData, DWORD dwNumDataBytes,
                      ID3D11UnorderedAccessView* pUnorderedAccessView,
                      UINT X, UINT Y, UINT Z ) {
    pd3dImmediateContext->CSSetShader( pComputeShader, NULL, 0 );
    pd3dImmediateContext->CSSetShaderResources( 0, nNumViews, pShaderResourceViews );
    pd3dImmediateContext->CSSetUnorderedAccessViews( 0, 1, &pUnorderedAccessView, NULL );

    pd3dImmediateContext->Dispatch( X, Y, Z );      // 通知显卡执行

    pd3dImmediateContext->CSSetShader( NULL, NULL, 0 );
    ID3D11UnorderedAccessView* ppUAViewNULL[1] = { NULL };
    pd3dImmediateContext->CSSetUnorderedAccessViews( 0, 1, ppUAViewNULL, NULL );

    ID3D11ShaderResourceView* ppSRVNULL[2] = { NULL, NULL };
    pd3dImmediateContext->CSSetShaderResources( 0, 2, ppSRVNULL );

    ID3D11Buffer* ppCBNULL[1] = { NULL };
    pd3dImmediateContext->CSSetConstantBuffers( 0, 1, ppCBNULL );
}

```
原文链接: https://www.cnblogs.com/ActionFG/archive/2012/09/09/2677466.html

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