Sidedness overrides are not working on the ALAB asset

[sirpalee]

Describescene_2108.usda.ziphe bug A clear and concise description of what the bug is.

To Reproduce Steps to reproduce the behavior:

1. Download the ALAB asset
2. Place the usda from scene_2108.usda.zip in the top directory (above USD_ALab_0730).

Expected behavior The outside shed should obstruct the view into the lab.

current result:

expected result:

Used Software Versions

• Arnold: 6.2.1.1
• USD: 21.08

[sirpalee]

This happens because the ID of the primitive being synced is pointing to the prototype rather than the mesh itself, and the primvars are only accessible on the base mesh.

For example, we get the path in the format of /root/thelab01/shed_grp/structure_proxywall_left_0001.proto_proxywall_left_geo_id0 instead of /root/thelab01/shed_grp/structure_proxywall_left_0001. I suspect this has changed around USD 21.02, when Hydra instancing got revamped, or we could be facing a bug.

A quick solution is to check if the ID we receive "IsPrimPropertyPath" and fall back to the parent path.

[sirpalee]

The behaviour is the same in 20.08, so it's not something that was recently changed. Possibly the code wasn't tested with instances or the point instancer.

[autodesk-oss-arnold-bot[bot]]

Issue synced internally to ARNOLD-13284

[compso]

need to confirm if this is fixed before closing