4 ms·

Could someone correct me? I am pretty new to graphics programing but I was learning wgpu (the Rust binding of WebGPU) the other day. I was under the impression

Could someone correct me? I am pretty new to graphics programing but I was learning wgpu (the Rust binding of WebGPU) the other day. I was under the impression that the shader language is GLSL (version 450) and it is then converted into SPIR-V. Would those limitations still apply with SPIR-V?

lights0123 5y ago
The shader language you write in does not matter, as it can be converted into whatever format the API expects. wgpu historically accepts SPIR-V, but the latest version released ~a month ago has moved to WGSL as much as it can in the examples. Have you upgraded yet?
- longstation 5y ago
  I haven't. I didn't realize the move. Looks like I need to find some new learning material. BTW, do you know any up-to-date tutorials?
- raphlinus 5y ago
  "Does not matter" is overstating the case. There are lots of tools for converting between shader languages (naga, spirv-cross, glslangValidator, dxc), but these conversions aren't 100% lossless and not all shader languages have the same capabilities. To give one example, HLSL (Shader Model 6) has a fairly complete set of subgroup (wave) operations, but is missing nonuniform shuffle. Another gap is that only GLSL (Vulkan flavor) has support for explicit memory semantics. Of course, WGSL currently has none of this, as it's something of a lowest common denominator. In the game world, it is very common to write shaders in HLSL because of good support on Windows, and then use the tools mentioned above to translate into other shader languages. I explored this for my own work but ultimately settled on GLSL because it allows access to advanced features. Fans of shader languages should also be aware of rust-gpu, which promises to be considerably higher level; most existing shader languages show their clear lineage to C (through Cg).
raphlinus 5y ago
This is still in transition, and the full story is complicated. The official shader language for WebGPU is WGSL, and that will almost certainly be the only language supported for web deployment. Originally this was going to be a textual representation that had exactly the same semantics ("bijective") as SPIR-V, but that's been diverging a bit[1]. Only very recently have atomics been added to the spec, and implementations are still catching up. Because WGSL is still under construction, for native deployment, wgpu supports SPIR-V shaders as well. On Vulkan, those are passed pretty much straight through to the GPU driver (with some validation). On DX12 and Metal, those are translated into HLSL and MSL, respectively. Until recently, in wgpu, all those translations were handled by spirv-cross. More recently, the new naga crate is doing those translations. Again, this is under construction and not everything works yet. [1]: https://kvark.github.io/spirv/2021/05/01/spirv-horrors.html https://kvark.github.io/spirv/2021/05/01/spirv-horrors.html
- longstation 5y ago
  I see. Thank you for the detailed information. I will read the linked content. I don't know if this is a good place to ask. But I was interested in wgpu because of the interest in building a cross-platform non-web UI library. I read a few of your articles and also looked at druid. I am pretty new to it and there seems to be no books on this topic. Do you have any recommendations?
  - raphlinus 5y ago
    Yes: don't. It's very hard. More seriously. There is very good reason to be encouraged about wgpu as a cross-platform low-level GPU drawing interface for UI work. There are already successful UI toolkits using it, of which probably the most impressive is iced. For 2D graphics in general, a good starting point is Diego Nehab's 2D graphics course. It has links to a bunch of resources including papers on GPU rendering. Of course, I'm working on my own stuff, which in time I hope will become a very strong foundation for building things such as UI toolkits, but it's not ready yet, and of course you're already aware of it. [1]: http://w3.impa.br/~diego/teaching/vg/ http://w3.impa.br/~diego/teaching/vg/
deleted 5y ago
[deleted]

lights0123 5y ago

The shader language you write in does not matter, as it can be converted into whatever format the API expects. wgpu historically accepts SPIR-V, but the latest version released ~a month ago has moved to WGSL as much as it can in the examples. Have you upgraded yet?

longstation 5y ago
I haven't. I didn't realize the move. Looks like I need to find some new learning material. BTW, do you know any up-to-date tutorials?
raphlinus 5y ago
"Does not matter" is overstating the case. There are lots of tools for converting between shader languages (naga, spirv-cross, glslangValidator, dxc), but these conversions aren't 100% lossless and not all shader languages have the same capabilities. To give one example, HLSL (Shader Model 6) has a fairly complete set of subgroup (wave) operations, but is missing nonuniform shuffle. Another gap is that only GLSL (Vulkan flavor) has support for explicit memory semantics. Of course, WGSL currently has none of this, as it's something of a lowest common denominator. In the game world, it is very common to write shaders in HLSL because of good support on Windows, and then use the tools mentioned above to translate into other shader languages. I explored this for my own work but ultimately settled on GLSL because it allows access to advanced features. Fans of shader languages should also be aware of rust-gpu, which promises to be considerably higher level; most existing shader languages show their clear lineage to C (through Cg).

raphlinus 5y ago

This is still in transition, and the full story is complicated. The official shader language for WebGPU is WGSL, and that will almost certainly be the only language supported for web deployment. Originally this was going to be a textual representation that had exactly the same semantics ("bijective") as SPIR-V, but that's been diverging a bit[1]. Only very recently have atomics been added to the spec, and implementations are still catching up. Because WGSL is still under construction, for native deployment, wgpu supports SPIR-V shaders as well. On Vulkan, those are passed pretty much straight through to the GPU driver (with some validation). On DX12 and Metal, those are translated into HLSL and MSL, respectively. Until recently, in wgpu, all those translations were handled by spirv-cross. More recently, the new naga crate is doing those translations. Again, this is under construction and not everything works yet. [1]: https://kvark.github.io/spirv/2021/05/01/spirv-horrors.html https://kvark.github.io/spirv/2021/05/01/spirv-horrors.html

longstation 5y ago
I see. Thank you for the detailed information. I will read the linked content. I don't know if this is a good place to ask. But I was interested in wgpu because of the interest in building a cross-platform non-web UI library. I read a few of your articles and also looked at druid. I am pretty new to it and there seems to be no books on this topic. Do you have any recommendations?
- raphlinus 5y ago
  Yes: don't. It's very hard. More seriously. There is very good reason to be encouraged about wgpu as a cross-platform low-level GPU drawing interface for UI work. There are already successful UI toolkits using it, of which probably the most impressive is iced. For 2D graphics in general, a good starting point is Diego Nehab's 2D graphics course. It has links to a bunch of resources including papers on GPU rendering. Of course, I'm working on my own stuff, which in time I hope will become a very strong foundation for building things such as UI toolkits, but it's not ready yet, and of course you're already aware of it. [1]: http://w3.impa.br/~diego/teaching/vg/ http://w3.impa.br/~diego/teaching/vg/

deleted 5y ago

[deleted]