ID3D11ComputeShader Interface

This interface represents a compute shader object in Direct3D 11.

Syntax


interface ID3D11ComputeShader : ID3D11DeviceChild
{
};

Methods

The ID3D11ComputeShader interface inherits from ID3D11DeviceChild, so it has no additional methods beyond those provided by the base interface.

Remarks

A compute shader is a type of shader that can execute arbitrary computations on the GPU, not just graphics-related tasks. Compute shaders are part of the DirectCompute programming model, which extends the shader pipeline to allow for general-purpose computation on the GPU.

Compute shaders are defined using High-Level Shading Language (HLSL) and compiled into shader bytecode. They are bound to the compute shader stage of the graphics pipeline.

Key Concepts:

Compute Shader Stage: A dedicated stage in the Direct3D pipeline for executing compute shaders.
Threads and Groups: Compute shaders operate on threads, which are organized into thread groups. This parallelism is crucial for efficient GPU computation.
Unordered Access Views (UAVs): Compute shaders can read from and write to UAVs, allowing for flexible data manipulation and storage.
Constant Buffers and Samplers: Like other shader types, compute shaders can access data through constant buffers and samplers.

How to Use

To use a compute shader:

Create a compute shader object by compiling HLSL source code using D3DCompile or by loading precompiled shader bytecode.
Bind the compute shader to the compute shader stage of the device.
Set any necessary input resources (like constant buffers, textures, and UAVs).
Dispatch the compute shader using the ID3D11DeviceContext::Dispatch method, specifying the number of thread groups to execute.
Read back the results from the output resources if necessary.

Example: Compiling and Binding a Compute Shader


// Assume 'pDevice' is a valid ID3D11Device pointer
// Assume 'pDeviceContext' is a valid ID3D11DeviceContext pointer

ID3D11ComputeShader* pComputeShader = nullptr;
ID3DBlob* pCSBlob = nullptr;
const char* hlslCode = R"(
    // HLSL compute shader code here
    RWTexture2D outputTexture;
    float4 main(uint3 dispatchThreadID : SV_DispatchThreadID) : SV_Target
    {
        // Perform computation based on dispatchThreadID
        float4 color = float4(dispatchThreadID.x / 1024.0f, dispatchThreadID.y / 768.0f, 0.5f, 1.0f);
        outputTexture[dispatchThreadID.xy] = color;
        return color;
    }
)";

// Compile the shader
HRESULT hr = D3DCompile(hlslCode, strlen(hlslCode), nullptr, nullptr, nullptr, "main", "cs_5_0", 0, 0, &pCSBlob, nullptr);

if (SUCCEEDED(hr))
{
    // Create the compute shader
    hr = pDevice->CreateComputeShader(pCSBlob->GetBufferPointer(), pCSBlob->GetBufferSize(), nullptr, &pComputeShader);
    if (SUCCEEDED(hr))
    {
        // Bind the compute shader to the compute shader stage
        pDeviceContext->CSSetShader(pComputeShader, nullptr, 0);

        // Set other resources like UAVs, constant buffers, etc.
        // ...

        // Dispatch the compute shader
        // For example, to dispatch 10x10 thread groups:
        // pDeviceContext->Dispatch(10, 10, 1);

        // After dispatching, you might need to unbind and flush.
    }
}

// Release resources
if (pComputeShader) pComputeShader->Release();
if (pCSBlob) pCSBlob->Release();

DirectX Graphics