gpuweb VS naga

People keep spreading this incredibly misleading statement, and yours is even more misleading (suggesting Apple opposed a 'GPU WASM')

By all accounts, Apple's /only/ stance was that if WebGPU used SPIR-V it would be a non-starter for them, due to ongoing legal issues between Apple and Khronos.

Apple actually proposed WebHLSL in collaboration with Microsoft, to have HLSL be the standard.

Mozilla employee's stance[0] was that SPIRV was too low level, did not fit with the goals of WebGPU portability and security, and expressed concern that Khronos may add functionality to SPIRV they cannot support in WebGPU like raytracing instructions .. 'So we'd always be on the verge of forking SPIR-V in some way.'

It was also noted by many people that even if a bytecode format was used, it would still have to be translated to the target (HLSL/DXIL, MSL, etc.) in almost the same way a text format would.

Nobody proposed a 'GPU WASM equivalent' or an alternative bytecode format.

The hard truth is that shader compilation is a fucking nightmare, people do not realize how bad it is across the different native APIs. SPIR-V is good, but it doesn't solve that - and presents other challenges if you are a web browser API. Vulkan and SPIRV are not the golden goose many make them out to be.

[0] https://github.com/gpuweb/gpuweb/issues/847#issuecomment-642...

Yes it is still a bit new. WebGPU is not finished and is still being worked on: https://webgpu.io/

WebGPU currently doesn't support the "bindless" resource access model (see: https://github.com/gpuweb/gpuweb/issues/380).

The "max number of sampled texture per shader stage" is a runtime device limit, and the minimal value for that seems to be 16. So texture atlasses are still a thing in WebGPU.

There's even an implementation under discussion to have the dp4a instruction added to WebGPU (https://github.com/gpuweb/gpuweb/issues/2677)

That wouldn't have been all that different from WGSL though, the most important thing is that whatever WebGPU uses for its shaders can be translated to and from SPRIV (and WGSL does that too (e.g. via https://dawn.googlesource.com/tint and https://github.com/gfx-rs/naga).

Hey all, wanted to put this link in here, where I'm proposing changing the API for errors in naga, so Naga can take ownership of error presentation and actually Make Shader Compilation Messages Comfy™: https://github.com/gfx-rs/naga/issues/2317

EDIT: There is also naga but it does not take HLSL as input: https://github.com/gfx-rs/naga but you can use DirectXShaderCompiler to compile to SpirV, then use naga to compile to Metal.

And it seems that naga https://github.com/gfx-rs/naga Already has a working front/backend for wgsl.

This is basically Ray Tracing support in Blade. So far, only ray queries are supported. Unlike prior work on ray tracing in Rust, this is original due to all shader code being WGSL, see the Naga PR.

There's a compiler that can translate from WGSL to SPIR-V called naga. Having such a compiler is essential, since WebGPU is planned to use WGSL and browsers are expected to implement rendering via Vulkan (and probably Metal and DX12).

Not sure about on the CPU, but naga is a shading language transpiler you can write custom front/backends for.

The spec docs are actually pretty useful https://www.w3.org/TR/WGSL/ besides that I was using naga's tests for reference https://github.com/gfx-rs/naga/tree/master/tests

For cross-platform support look at WebGPU and Vulkan (e.g,: [0] [1]. Essentially, you would need to write the func in WGSL or GLSL, HLSL or MSL. Each of these can be cross-compiled to SPIR-V (what Vulkan needs) with cross-compilers such as spirv-cross and naga.