WebASM build of USD

[marsupial]

Hello!
In the USD-WG both @philsawicki and I have demoed pieces of getting USD working in a web-browser, and are pretty interested in getting this running. There are still some caveats, but wanted an issue to track some smaller PRs that can help building with emscripten.

Ideally embedding a demo in this issue would be possible, or even a preview via GitHub Pages, but not yet due to the lack of CORS headers.

If you checkout the branch and run a local server.py though, you can load and interact with a USD file. Rendering is using a Hydra delegate for Filament, which has a WebGL backend (but also works on the desktop in Houdini, Maya).

I've tried separating out the more trivial commits that should be non controversial (27f3d17 or aa7f517).
There's also a group devoted to compiling cleanly on clang to not obscure actual both for emscripten, but also Android and iOS.
And some possibly more controversial things (like 0b7bcf1, which is generally useful for sandboxed environments where PXR_PLUGINPATH_NAME can't necessarily be setup before the library is loaded).

I'll start doing some PRs, but feel free to cherry-pick anything that looks appealing, thanks!

HdFilament.mp4

[mistafunk]

Such a cool timing - we are just investigating the same... 👍

[marsupial]

A lot of people are!
The renderer isn't included yet for re-building, but USD can be built pretty easily with a build script.

Getting bindings [that closely match Python] is probably the biggest need right now.

[jilliene]

Filed as internal issue #USD-6657

[donmccurdy]

It'll take a while to load, but you can get a live demo from this branch using the GitHack CDN. The link below is currently working for me in Chrome, but failing in Firefox with errors about SharedArrayBuffer. This link will update automatically as the underlying git branch changes:

https://raw.githack.com/marsupial/USD/HdFilament/extras/imaging/examples/hdFilament/index.html

[marsupial]

@donmccurdy, thanks for the info! The SharedArrayBuffer error in Firefox is because two CORS headers (Cross-Origin-Opener-Policy, Cross-Origin-Embedder-Policy) not being served AFAIK.

As mentioned in the threejs issue, the file size is 35MB, but a little over 21MB of that is due to the embedded usdz files (and most of that is because of the png-textures).

The next step is to get the Filament delegate source up so the whole thing can build properly and work without the embedded content. I and a few others are meeting monthly to try and push this further if you're interested in helping.

[jeffscottward]

A lot of people are!
The renderer isn't included yet for re-building, but USD can be built pretty easily with a build script.

Getting bindings [that closely match Python] is probably the biggest need right now.

i built it, what do now?