I was doing some experimenting with scene index plugins in Houdini 19.5 and noticed that they only seem to run interactively, not when a render delegate that uses them is loaded via husk.
I think the reason for this has to do with scene index plugins that are specific to a particular renderer relying on HdRenderDelegate::GetRendererDisplayName() returning an expected value in order for them to be loaded by the plug-in registry. When running with husk I'm seeing that method always return an empty string, but it returns the expected render delegate name in Solaris. Does this sound like a bug, or does anyone have any experience with getting around this?

Katrin

Hi Katrin, we haven't tried building or using any scene index plugins, so I don't really know how to help here. HdRenderDelegate::GetRendererDisplayName is a virtual function of your delegate, so I don't see how we could be affecting the returned value. There is also the static UsdImagingGLEngine::GetRendererDisplayName method, which can return an empty string if it can't find the specified renderer id in the HdRendererPluginRegistry. But I would expect prman to be in that registry when running husk (or we wouldn't be able to instantiate a prman render delegate). If you could point me to where scene index plugins are loaded maybe I could take a guess about where husk might be interfering or just behaving differently from Houdini...

Hi Mark,
This is the line where I think the scene index plug-ins get loaded, which appears to be called as expected in interactive Solaris but not husk:
https://github.com/PixarAnimationStudios/USD/blob/release/pxr/imaging/hd/renderIndex.cpp#L134 [github.com]

This is where it looks like the delegate display name gets set:
https://github.com/PixarAnimationStudios/USD/blob/release/pxr/imaging/hd/rendererPluginRegistry.cpp#L112 [github.com]

This change is an example of a scene index plugin. It adds a "loadWithRenderer" tag to the hdPrman plugInfo.json, which should cause the scene index plug-in to be loaded when hdPrman is loaded.
https://github.com/PixarAnimationStudios/USD/commit/c8b4a77c374e7db7a6e51562040d5692fba68c63 [github.com]

It looks like husk is not using the "normal" method of creating the render delegate. I'll submit a bug. Thanks for noticing this, and all the pointers into the USD code!

Hi Katrin,

This should be better in tomorrow's build. Please let us know if we've still got it wrong.

Thanks,