Issue: Multiple Issues with the adsk/feature/wasm Branch

[xiejiashu]

We are encountering several critical issues while working with the adsk/feature/wasm branch of Autodesk USD. Below are the details of the issues:

1. Nested USDZ Files Not Parsing Correctly
   Problem: When dealing with USDZ files that contain multiple layers of nested files, the parsing fails or results in incomplete or incorrect data.
   Steps to Reproduce:
   Load a USDZ file containing multiple nested USD files.
   Attempt to parse and load the contents into the WebAssembly (WASM) environment.
   Observe that nested USD files are not loaded correctly, leading to missing data or errors.
   Expected Behavior: The parser should correctly handle nested USDZ files and load all the included assets.
   Additional Information: This issue appears to be specific to complex USDZ files with multiple layers of nested files (including textures, animations, and other assets).
2. Textures Under GeomSubset Not Handled Properly
   Problem: Textures associated with GeomSubset prims are not handled correctly. When attempting to display or access the textures, they appear as missing or incorrectly mapped.
   Steps to Reproduce:
   Load a USDZ file containing GeomSubset prims with textures.
   Observe that the textures do not load or are incorrectly mapped to the 3D model.
   Expected Behavior: Textures should be correctly applied to the geometry subsets and rendered as expected.
   Additional Information: This issue is likely related to how texture attributes are processed and associated with GeomSubset prims in the WebAssembly (WASM) environment.
3. Some Animation Primitives Not Playing
   Problem: Animations associated with certain USD primitives do not play correctly or are completely missing in the WebAssembly environment.
   Steps to Reproduce:
   Load a USD or USDZ file with animations attached to one or more prims.
   Attempt to play the animations.
   Observe that certain animations fail to play or display an error.
   Expected Behavior: All animations, including those attached to complex or non-standard prims, should play as expected in the WASM environment.
   Additional Information: This issue might be related to the handling of certain animation types or keys, or a lack of support for specific animation primitives in the WebAssembly build.
   Suggested Improvements / Fixes:
   Nested USDZ Parsing: Ensure that the parser can correctly handle nested USD files and the relationships between them (e.g., including texture paths and references).
   Texture Handling for GeomSubset: Investigate how textures are applied to GeomSubset prims and ensure proper texture mapping is done during the parsing process.
   Animation Playback: Review the handling of animation primitives to ensure that all types of animation (including complex ones) are supported in the WASM environment.
   Additional Notes:
   The issues mentioned above are specifically observed in the adsk/feature/wasm branch, and they seem to impact both the usability and accuracy of the USD to WebAssembly pipeline.
   If there are any logs or debug information needed, I can provide those for further investigation.

Thanks for your time and consideration. We hope these issues can be addressed to improve the usability and functionality of the WASM implementation of USD.