Distorted monochrome textures in Storm

[rasmusbonnedal]

Description of Issue

When using mono channel textures where width is not dividable by 4 we are experiencing distortion in Storm.

The left texture is 500x500, the right is 501x500.

Steps to Reproduce

1. Open this stage in usdview using GL renderer.
   repro.zip

The distorted texture is generated like this:

oiiotool --pattern checker:width=100 501x500 1 -o checker_501.png

The issue is present with both USDPreviewSurface and MaterialX materials. Same result with PNG and JPEG images.

From Jono Gibbs on ASWF Slack:
"Just tried it with my build of 24.08 on macOS and it works, so it could be a Windows thing?"

System Information (OS, Hardware)

• Windows 11, Thinkpad T14 (AMD Ryzen 7840U, Radeon 780M)
• Windows 10, Dell Precision 5690 (NVidia RTX 2000 Ada)
• Ubuntu 24, WSL2 on same Thinkpad T14 as above

Package Versions

• dev branch from 2024-08-29 (#6030846ba)
• 24.05

Build Flags

python build_usd.py c:\WORK\USD\usd-24.11-dev-py310

[rasmusbonnedal]

Jakub Jaroszek found this possible cause:
https://stackoverflow.com/questions/57346317/opengl-greyscale-texture-data-layout-doesnt-match-when-the-dimensions-arent-d

I tried the suggestion by inserting this in Stråla before initializing Hydra:

glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

and it fixes the issue.

[jesschimein]

Filed as internal issue #USD-10051