Houdini 21 (Hydra Scene Index mode): native Houdini primitive geometry does not render in hdMoonray

[codesavory]

Under Houdini 21, Hydra runs in Scene Index mode, and hdMoonray doesn't render native Houdini primitives. A Sphere LOP renders blank with Moonray, but renders fine in Houdini GL, and a USD asset (crag) renders fine with Moonray. So the geometry is valid and the delegate works; only native primitives in Scene Index mode fail.

Env: macOS Apple Silicon, Houdini 21.0.631, Houdini USD 23.x (v0_25_5), Python 3.11, hdMoonray 6.41.0.0, scalar exec mode.

Repro:

1. Sphere LOP in Solaris, render with Moonray → blank.
2. Same sphere, Houdini GL → renders.
3. crag.usd with Moonray (Debug) → renders.

Sphere + Moonray (blank):

Sphere + Houdini GL (renders):

crag.usd + Moonray Debug (renders):

Rob Wilson confirmed on ASWF Slack this is a known Scene Index limitation he's working on:

if you are using Houdini 21, it is running Hydra in SceneIndex mode. There are few things that don't work in that mode, including primitive geometry. I'm currently working on fixes for these issues.

Slack thread: https://academysoftwarefdn.slack.com/archives/C0AHKA6E17Z/p1776195285395069

I have a working Houdini 21 / macOS build and am happy to help fix this — pointers on where Scene Index primitive handling lives would be welcome.

[rolledhand]

Hey, I just got this one to work yesterday, I'll be pushing the changes today on my forks and send it to you. Also trying to fix the AOVs etc.

Did you build on Tahoe/Seqoia btw? I'm about to downgrade to Sequoia today since I started having some Clang during build issues w/ the latest Tahoe.

The primitive handling lives in the hdMoonray where I'm currently trying to aling h20.5 USD/hydra requirements w/ Moonray for the translation layer - at least assuming it works and should be handled that way.