Wgpu: Software rendering

[Korijn]

What's the wgpu story with regards to software rendering? Would something like OSMesa work as a backend?

(Perhaps this question better belongs to the wgpu-native repo, I was unsure)

[kvark]

@Korijn Current story is to rely on the SW implementations of the native backends:

• on Vulkan there is swiftshader
• on D3D there is a Warp adapter, which we could pick (already) if we had any sort of "software" flag in the adapter descriptor
• on OpenGL there is OSMesa, but gfx/wgpu OpenGL backend is by itself pretty fragile still, so it needs to mature more before we can expose it and make usable.

[Korijn]

Alright, so on Linux, I should be able to build swiftshader and run wgpu-native with it. Would that require any special settings or compiler/linker options?

It would be ideal if all it took was the presence of swiftshader as described in their docs. Is that the case for wgpu-native?

On Linux, the LD_LIBRARY_PATH environment variable or -rpath linker option can be used to direct applications to search for shared libraries in the indicated directory first.

[kvark]

Assuming SwiftShader can be used via the Vulkan Loader ICD interface, you'd just run your app on Linux with VK_ICD_FILENAMES=<path_to_swiftshader_icd.json>. wgpu wouldn't necessarily know that it works with swiftshader.

[Korijn]

I'll see if I can find anything like that in their docs/source.

Thanks so far!

Edit: looks like an ICD JSON file is included in the build output: https://github.com/google/swiftshader/commit/e7ce4e53915d026720005ca2c1831a5c28f77b3f

I'll be giving this a shot sometime soon with wgpu-py in a docker container.

[kvark]

FWIW, last I heard, swiftshader assumes a very specific use by an application. It's not build (at least yet) as a general purpose Vulkan implementation. Rather, it's made to work well with Angle on Vulkan. So beware of dragons when you test this, but I'm following your work with anticipation :)

[Korijn]

We'll see! :)

[Korijn]

Just wondering if there have been any developments in this regard? :) Judging from #969 the Vulkan software renderer by mesa is still in development.

[kvark]

I don't think we have any actions to do here. If you want to test Mesa's LavaPipe today, you can do it. Since it's a regular Vulkan driver, no changes are needed on wgpu side.

[cwfitzgerald]

Closing as no-action needed