Ray Queries

[Vecvec]

Connections
Works towards #1040

Description
This PR provides BLASes (bottom level acceleration structures), TLASes (top level acceleration structures), TLAS instances (which contain BLASes and data, like transforms, about them), TLAS packages (which contain vectors of TLAS instances).

Testing
Running tests & examples included in PR

This a updated version of #3631 and is intended to replace it.

Checklist

• Run cargo fmt.
• Run cargo clippy. If applicable, add:
  • n/a --target wasm32-unknown-unknown
  • n/a --target wasm32-unknown-emscripten
• Run cargo xtask test to run tests.
• Add change to CHANGELOG.md. See simple instructions inside file.
• More tests & examples.
• More docs

Later (follow-up PR)

• Acceleration structure compaction.
• Procedural geometry.
• as_hal methods

[Vecvec]

I have noticed that quite a few resources use snatchables and it seems that they are used in resource destruction if the resource is in something such as a bind group, I will implement snatch guards for BLASes and TLASes while @cwfitzgerald works on moving the validation away from a mutable state on the BLAS/TLAS.

[Vecvec]

@cwfitzgerald you were working on moving the validation away from a mutable state on the BLAS/TLAS, do you know how long that might take? It seems that other people are working off this branch (for example: #1040 (comment)), so it would be useful to get this branch into trunk.

[JMS55]

I coincidentally had just asked @cwfitzgerald about this on matrix. Posted their response below, with the first part paraphrased.

[explaining that they don't have time to work on this anymore]. However we don't actually want to block it at this stage so our resolution to this problem is to let it in basically as is. The one change that we want to make is prefix the feature flag with EXPERIMENTAL_ so that people will expect it to not work sometimes or break or break your computer [or] whatever.

So sounds like we can merge once you rename the feature flag :)

[cwfitzgerald]

Good after failing CI fixed

[JMS55]

Thanks so much @Vecvec! What a great birthday present ❤️

[teoxoy]

I noticed that this PR makes use of pending_writes but the operations adding things in pending writes are on the command encoder. Pending writes is only needed for queue operations that require a hal command encoder to be executed (ex write_buffer). I think the way the new command_encoder_build_acceleration_structures use pending writes is not sound or at least not what it was designed for. Shouldn't we add things to the command encoder itself rather than into pending writes?

[teoxoy]

Tlas.destroy don't seem to check if the Tlas is used in a bind group of an active submission. The only reason we need the destroy methods for textures and buffers is because they allow users to eagerly release memory in browser implementations. I think we can remove the destroy methods on the acceleration structures for now as they complicate the picture without any gain. If they will be needed for Firefox we can add them back.

[teoxoy]

I put up a PR with these changes ^. Could someone test it?