Add support for KHR_draco_mesh_compression in glTF/glb export

[viktor-hallen]

Feature request: Draco mesh compression on glTF/glb export

Background
From what I understand, the USD_FILEFORMATS_ENABLE_DRACO CMake option currently enables reading Draco-compressed meshes on import. However, there appears to be no support for exporting glTF files with KHR_draco_mesh_compression.

Use case

• Large USD scenes generate very large glTFs; mesh data dominates file size.
• Draco compression could reduce mesh payloads by ~60–80%, speeding up delivery in web and real-time viewers.

Proposal
Introduce enableDracoCompression (or similar) in ExportGltfOptions.

Alternatives considered

• Post-processing with external tools, but integrating at export avoids extra steps in our USD-centric pipelines.

Thanks for considering this enhancement!

[jmerrell-adobe]

Viktor, we agree this would be a good feature to add for both reduced file size and better parity with the spec.

We're using tinyGLTF right now to read and write GLTF files and it doesn't look like that library has support for draco mesh compression yet: https://github.com/syoyo/tinygltf/issues/207.

If/When tinyGLTF has support for draco mesh compression we'd like to enable it here. We don't have the bandwidth right now to make the contribution to tinyGLTF though. But we might in the future.

Either way, thank you for pointing this out! We'll leave this open for further discussion. If others feel this need, please speak up for it here.