Resolution of UDIM texture paths inside USDZ archives fails

[dalorin]

Description of Issue

It is not possible to resolve paths to UDIM textures that are located inside a USDZ archive. This is because the utility function _ResolveAssetAttribute located in materialParamUtils.cpp does not account for the presence of usdz reference syntax e.g. /path/to/file.usdz[0/texture.png] when sanity checking the suffix post-resolution here. As a result, the return SdfAssetPath object does not contain a resolved path and renderers will treat texture paths such as "0/texture.png" as absolute and fail.

Steps to Reproduce

1. Create a USD file containing a model with attached texture using UDIMs.
2. Run usdzip with -a flag against the USD file to create a usdz archive containing the texture files.
3. Attempt to render the usdz archive with a hydra render delegate. In the case of arnold, the following output is produced:
   00:00:00 535MB ERROR | [texturesys] could not read resolved image filename = "2/alien_Opacity.1007.tif"

System Information (OS, Hardware)

CentOS 7, python 2.7.17

I have a patch for this issue that I will raise in a pull request if this issue is confirmed.

[jilliene]

Filed as internal issue #USD-6786

[sunyab]

Hi @dalorin, I can confirm the issue is exactly as you've said. We have a fix internally pending review and testing but it'll be at least a week or so before we can push that up due to some office outages. I'll add some notes to the PR as well. Thanks!