Mesh Shaders

[inodentry]

Mesh Shaders are an exciting new kind of rendering pipeline for modern hardware, that directly combines compute and rasterization.

KHRONOS recently officially released an extension for Vulkan, which is now quickly gaining support in different drivers. DX12 has had them for a while now. Metal (to my knowledge) also has them. Therefore, it should now be available on at least all the desktop platforms (given compatible hardware) and iOS.

Would it be possible for wgpu to provide access to this functionality?

There is a WebGPU tracking issue for it: gpuweb/gpuweb#3015 , but looks like it is not a priority and unlikely to be added to the WebGPU standard soon.

Perhaps wgpu could support it as a "native-only" extension?

[expenses]

Mesh shaders as a native-only extension should be simple enough to implement, at least for vulkan. I'd like to look into this but I don't have a huge amount of free time to do so (similar to #1040 (comment)).

For anyone else interested, https://github.com/nvpro-samples/gl_vk_meshlet_cadscene is a vulkan example that uses the new VK_EXT_mesh_shader extension.

[heavyrain266]

Mesh shader extension in WGSL could be really helpful for maintaining e.g. PSSL support in naga and PS5 API in wgpu, current implementation avoids usage of wgsl and requires rewriting all shaders in PSSL which is rather annoying to maintain.

[zmarlon]

Since there are now mesh shaders on DX12, Metal and Vulkan, it would at least be possible on all modern APIs. DX11, OpenGL ES and WebGPU would of course not work. Would there be any interest in seeing mesh shaders in WGPU? If so, I might try to implement it.

[cwfitzgerald]

There definitely is interest! It's going to be a big project though, so do join us in the chat room to chat about the design before starting work.

[JunkuiZhang]

Any progress have been made? Its a very exciting feature and maybe the future of game engine dev.

[lylythechosenone]

Indeed, I would like to know this too. Has work actually started yet, or is this still just an idea?

@cwfitzgerald

[cwfitzgerald]

No one has taken lead in it - it's a rather involved thing, needing both improvements to Naga and wgpu.

If someone was so motivated, we could walk through potential implementation plans.

[ZoopOTheGoop]

Tag me in, I'd need a bit of a push in the right direction, but I'm willing to do the legwork.

[JMS55]

I'm not a wgpu maintainer, and can't help implement it, but I'd be happy to help test it out if you do implement mesh shaders. It's a feature I've been very much wanting.

In terms of implementation you would need to:

• Figure out the common denominator between metal/vulkan/dx12 for an API to implement
• Figure out all the edge cases and things that could go wrong, and how you would add validation for it
• Add mesh shader support to naga's WGSL frontend
• Add mesh shader support to naga's spirv/hlsl/msl backends

I definitely encourage you to join the matrix channel linked in the wgpu readme and talk to the wgpu devs there if you want to implement mesh shaders.