Weird behaviour with prman and storm in custom viewer


I have a custom viewer, in which I’m using a UsdImagingGLEngine out of the box.
With USDIMAGINGGL_ENGINE_ENABLE_SCENE_INDEX enabled, if I start the viewer with Storm enabled, then switching to Prman, it can’t render any material anymore apparently (not even displaying displayColor values).
But if I launch the viewer with any other delegate enabled (or Prman itself), then I can go into Storm and back in Prman and it’s all good.
With the SceneIndex disabled, it’s all fine.
This is with usd-24.05 (and tested on 23.11 and 24.03 too ).

Has anyone noticed anything like this ?


I think without images this thread isn’t so interesting, so… here they are :slight_smile:

I can start the viewer in a custom delegate and switch to Prman and then to Storm… (top to bottom)

but if I start with Storm as first delegate, then switching to Prman results in no-materials and no displayColor (on the cornellBox planes) (top to bottom)

I’m pretty sure I’m doing something wrong…