In mantra there was vm_rendervisibility which let you compose the visibility bit mask using a human readable string with simple syntax. There was also a dropdown with common choices.

There is a ‘visibility mask’ primvar on the rendergeometrysettings node for Karma, but it's an integer that takes a raw bitmask. Until there's some better UI for this, is there a table or some tool/python that can be used to convert mantra visibility string to a karma bitmask?

Right now, the visibility mask is set using the USD purpose render tags.

https://graphics.pixar.com/usd/docs/api/class_usd_geom_imageable.html#a6071458f7f849cb36a1b467795f2c1aa [graphics.pixar.com]

We realize this is limiting, and will likely expand on this in the future.

would be great to have something as powerful as LPE for defining visibility

This has been on my list of queries for Solaris so thanks for the hints, but I'm not sure the link to the USD purpose tags has helped me get my head around it.

We're looking to (for example) make an object invisible to primary (camera) rays i.e. phantom. I've had no luck using the Visibility Mask on the Render Geometry Settings node - the int bitmask value is set on the relevant paths but I've not been able to find a value for that attribute that has any effect.

Setting ‘Is Matte’ works fine for hold outs, but it would seem very natural to have a simple ray visibility control on that Render Geometry Settings node too.

Do you (Mark) have an example of how to approach this (phantom) with purpose tags?

cheers

The purpose tags cannot set per raystyle visibility. This feature is just not implemented yet.

I really like what you have done with the light linker. I wish visibility could be set with a similar tool specifically a visibility linker.

Thank you, this thread helped me alot.