Add compute shader indirect dispatch on Vulkan?

[comradez]

The dispatchComputeIndirect for Vulkan compute encoder has always been unimplemented.

I am using Falcor on Linux and trying some indirect dispatched compute shaders. As the dispatchIndirect call from Falcor goes through slang-gfx to the backend, I guess the only way to make it work is to implement vk::ComputeCommandEncoder::dispatchComputeIndirect.

Given that there is an implementation for D3D12, is any reason why this remains unimplemented, and are there possibilities to implement it? Very thanks!

[bmillsNV]

@comradez this hasn't been implemented due to resource constraints. We are also moving to Slang-RHI as a replacement for slang-gfx. Can you try Slang-RHI repo instead and file an issue there for any gaps?

[comradez]

Thanks @bmillsNV for answering, but I can't do an easy switch for now as I'm using Falcor and I don't want to overhaul their codebase. For now I'll just do a read back to get things quickly done.

I'll keep an eye on the new RHI library, and do you have a roadmap for this? Thanks.

[AdamYuan]

Hi @comradez , I've also encounter this issue recently. So I try to implement vk::ComputeCommandEncoder::dispatchComputeIndirect in a fork (https://github.com/AdamYuan/slang/tree/falcor-8.0-better-vk) and it turns out to be a perfect solution.

If you want to use the fork in Falcor (v8.0), simply replace

    <remote name="github-slang" type="https" packageLocation="github.com/shader-slang/slang/releases/download/v${version}/slang-${version}-${platform}.zip"/>
    <dependency name="slang" linkPath="external/packman/slang">
        <package name="slang" version="2024.1.34" remotes="github-slang" platforms="windows-x86_64 linux-x86_64"/>
    </dependency>

with

    <remote name="github-slang" type="https" packageLocation="github.com/AdamYuan/slang/releases/download/v${version}/slang-${version}-${platform}.zip"/>
    <dependency name="slang" linkPath="external/packman/slang">
        <package name="slang" version="2024.1.34-better-vk" remotes="github-slang" platforms="windows-x86_64 linux-x86_64"/>
    </dependency>

in dependencies.xml and refresh the packman cache.