= DKComputeShader 101 =

== 1. Get the ComputeCommandQueue from the Device ==
for sure
{{{#!highlight C++ 
DKObject<DKGraphicsDevice> device = DKGraphicsDevice::SharedInstance();
DKObject<DKCommandQueue> computeQueue = device->CreateCommandQueue(DKCommandQueue::Compute);
}}}



== 2. Prepare the Gpu resources ==

=== 1. Texture ===
Texture usage decription should has one of these flags.

{{{#!highlight C++ 
DKTexture::UsageStorage // Recommended
DKTexture::UsageShaderWrite // Could be deprecated soon
}}}

Texutre Decriptor Example
{{{#!highlight C++ 
DKTextureDescriptor texDesc = {};
texDesc.textureType = DKTexture::Type2D;
texDesc.pixelFormat = DKPixelFormat::BGRA8Unorm;
texDesc.width = w;
texDesc.height = h;
texDesc.depth = 1;
texDesc.mipmapLevels = 1;
texDesc.sampleCount = 1;
texDesc.arrayLength = 1;
texDesc.usage = DKTexture::UsageStorage                               // For Compute Shader
              | DKTexture::UsageSampled | DKTexture::UsageShaderRead; // For Fragment Shader
textureTarget = device->CreateTexture(texDesc);
}}}


=== 2. Shader ===
In DKGL2, we use same class for all type of shaders.


=== 1. LoadResourceData From the resource path ===
{{{#!highlight C++ 
DKObject<DKData> computeShaderData = resourcePool.LoadResourceData("shaders/ComputeShader.comp.spv");
}}}


=== 2. Create Function from data above step ===
{{{#!highlight C++ 
DKGraphicsDevice* device = queue->Device();
DKShader shader(shaderData);
DKObject<DKShaderModule> shaderModule = device->CreateShaderModule(&shader);
DKObject<DKShaderFunction> shaderFunc = shaderModule->CreateFunction(shaderModule->FunctionNames().Value(0));
}}}


== 3. Prepare Uniformbuffers and BindSet ==
TODO


== 4. Prepare the Pipeline ==
Ususally compute shader need only setting for compute function.
Set the shader function to the Pipeline Descriptor

{{{#!highlight C++ 
DKComputePipelineDescriptor computePipelineDescriptor;
computePipelineDescriptor.computeFunction = csFunction; // csFunction as DKShaderFunction
auto computePipeLine = device->CreateComputePipeline(computePipelineDescriptor);
}}}


== 5. CommandBuffer Encoding ==

{{{#!highlight C++ 
DKObject<DKCommandBuffer> computeCmdbuffer = computeQueue->CreateCommandBuffer();
DKObject<DKComputeCommandEncoder> computeEncoder = computeCmdbuffer->CreateComputeCommandEncoder();
if (computeEncoder)
{
    if (computebindSet)
    {
        computebindSet->SetTexture(0, texture);
        computebindSet->SetTexture(1, targetTex);
    }
    computeEncoder->SetComputePipelineState(computePipeLine);
    computeEncoder->SetResources(0, computebindSet);
    computeEncoder->Dispatch(width / 16, height / 16, 1);
    computeEncoder->EndEncoding();
}
}}}