[Feature Request] SDL3 GPU Backend for WebGPU Target

[ShadowMarker789]

Issue created to track SDL3 GPU Backend, targeting WebGPU.

Extract from SDL_GPU Readme page

Future plans are to also support:
• WebGPU

SDL3 GPU is a very exciting project, and it would be great to add WebGPU as a compilation target.

Many thanks to the SDL Team for their hard work and great accomplishments.

[icculus]

This is definitely something I want, but I reasonably doubt anyone will have time to work on this before SDL3 ships.

I'm going to assign this to myself and put it in the 3.2.0 milestone, though I believe both actions are delusional on my part.

[slouken]

FYI: https://x.com/kylelukaszek/status/1832979451203686676

[ericoporto]

Yeah, apparently development is happening here

https://github.com/klukaszek/SDL
https://github.com/klukaszek/SDL3-WebGPU-Examples

@klukaszek

[leandro-benedet-garcia]

FYI: https://x.com/kylelukaszek/status/1832979451203686676

Sorry, could you post a screen shot? Twitter is banned in my country.

[ShadowMarker789]

FYI: https://x.com/kylelukaszek/status/1832979451203686676

Sorry, could you post a screen shot? Twitter is banned in my country.

Video to the right shows a rapid flickering of various colors, like one is randomly picking a color and clearing the screen with it.

[klukaszek]

Hey! I’ve been working on this in my spare time and I’ve managed to get the driver entry working for the example test suite. I’m planning on getting to work on pipeline creation tonight after I do my homework lol.

[klukaszek]

Cycling between demos using A and D will result in failure due to missing function implementations for the GPU driver. I also had to kind of hack in a way to prevent mouse events from flooding the event queue, but I believe this has to do with the browser and not SDL itself.

[klukaszek]

The crashing mentioned in the earlier tweet was a result of a problem where any event would trigger a resize event causing swapchain recreation. This has been solved.

So far I’ve tested resize, mouse, and key events and they all work as if using SDL2 on web.

Sorry for the spam, I’m just writing from my phone waiting for class.

[icculus]

Talk all you want, this is awesome. :)

[flibitijibibo]

Something that may help move this along is migrating our examples repo over:

TheSpydog/SDL_gpu_examples#12

Since we presumably need to make changes for Emscripten and the examples folder has automation for exporting web samples, doing these together seems like a good idea.

[klukaszek]

Here's the latest update on my WebGPU progress.

https://x.com/KyleLukaszek/status/1839631105646862343

Video for those of you who don't have access to Twitter:

2024-09-27.07-18-37.mp4

Update

I ended up DM'ing with @ beaufortfrancois (Google Chrome) and he told me that the SPIR-V support for Chrome was bugged and never worked properly. The team decided to scrap SPIR-V support altogether and will be removing it from Chromium as of the next release.

This presented an interesting problem. SDL uses SPIR-V as its shader type, but browsers will require a valid WGSL WGPUShaderModule to process the shader.

I ended up porting Google's Tint WGSL compiler with limited functionality to WASM and linking it with the Emscripten build of SDL. This allowed me to access the Tint C++ API and export wrapper functions to C for converting SPIR-V bytecode to WGSL.

This is not an elegant solution, but I did not feel like completely changing how shaders are handled in SDL.

Anyway, I am mostly concerned at this point about being 100s of commits behind the main branch now. Any tips for syncing?

[klukaszek]

Here’s a live demo to test the current status of the example suite.

www.kylelukaszek.xyz

[flibitijibibo]

For the WebGPU backend you'll likely end up adding a WGSL value to the bitflags, so shaders can be passed directly to SDL without needing an extra compiler (that can be the app's problem).