Bindless structured buffers & raw buffers

[dolphineye74]

Hi,

I was playing a bit with bindless buffers in Diligent based on Tutorial16_BindlessResources:

...

#ifdef VULKAN
...

ByteAddressBuffer g_BigBuffer[1];

#else

...

ByteAddressBuffer g_BigBuffer;

#endif

...

void main(in  PSInput  PSIn,
          out PSOutput PSOut)
{
    ...

    // Bindless buffer access
    uint4 BufferData = g_BigBuffer.Load4(0);
    float4 ConstantColor = asfloat(BufferData);
    PSOut.Color *= ConstantColor;
}

and

// Creating the buffer
BufferDesc BigBufferDesc;
BigBufferDesc.Name      = "Big buffer"; // Use default usage as this buffer will only be updated when grid size changes
BigBufferDesc.Usage     = USAGE_DEFAULT;
BigBufferDesc.BindFlags = BIND_SHADER_RESOURCE | BIND_UNORDERED_ACCESS;
BigBufferDesc.Mode      = BUFFER_MODE_RAW;
BigBufferDesc.Size      = sizeof(float4);
m_pDevice->CreateBuffer(BigBufferDesc, nullptr, &m_BigBuffer);
CHECK_FATAL_ERR(m_BigBuffer);
float4 ConstantColor = float4(1, 1, 0, 1);
m_pImmediateContext->UpdateBuffer(m_BigBuffer, 0, sizeof(ConstantColor), &ConstantColor, RESOURCE_STATE_TRANSITION_MODE_TRANSITION);

It works correctly in D3D12 but it appears that Vulkan won't work correctly due to GLSLANG.

By any chance have you figured out a way/workaround to use bindless buffers on the Vulkan backend?

Thanks 🙏

[dolphineye74]

I figured this out, so I'm sharing the information here for anyone else in the same situation.

The solution is to use the DXC compiler as follows:

shaderCreateInfo.ShaderCompiler = Diligent::SHADER_COMPILER_DXC;

You might also need to specify the DXC compiler's path when you create your render device:

vkEngineCreateInfo.pDxCompilerPath = "<VulkanSDK>/Bin/dxcompiler.dll";

[TheMostDiligent]

You shader looks incorrect.
For Vulkan you have:

ByteAddressBuffer g_BigBuffer[1];

This should be accessed as

uint4 BufferData = g_BigBuffer[0].Load4(0); 

But you are missing the array index. I expect this was the reason for the crash, though I can't tell exactly; logs would have more information, but you did not provide them.

[dolphineye74]

The reason was I was using the default HLSL compiler for Vulkan which does not support buffer arrays. I switched to the DXC compiler with SM6.0 and now everything works like a charm. Thanks for helping anyway :)