How could I use my group as matte in Karma render?

I has two group "inside" and "outside" in RBD geometry sop, I want to set this two group as my matte passed in Karma, hou can I do that? thanks!

They would need to be separate prims. Groups are translated as geomsubsets, which only support different material assignments, not different render settings.

The name or path attribute can be used to put different geo into different prims, which can be done in sops using the existing groups.

On this topic, I was trying to use the geometry subset LOP the other day to create subset prims based on a similar inside/outside attribute, and the LOP configuration simply eluded me. If anyone has an example of how that's done, I'd love to see it.

Tim Crowson
On this topic, I was trying to use the geometry subset LOP the other day to create subset prims based on a similar inside/outside attribute, and the LOP configuration simply eluded me. If anyone has an example of how that's done, I'd love to see it.

If it's groups, I think a simple checkbox is all it takes. Otherwise there's some lops for that like materialassign and geometrysubsetvop.

jsmack
Otherwise there's some lops for that like materialassign and geometrysubsetvop.

Right that's what I mean...I tried this but my vop-fu sucks.

Tim Crowson

jsmack
Otherwise there's some lops for that like materialassign and geometrysubsetvop.

Right that's what I mean...I tried this but my vop-fu sucks.

It's a tad confusing to get rolling, but the help is at least a little demystifying. The upside is that the actual vop-fu is very simple if all that entails is a simple mapping from an existing uniform primvar.

Oh thank you! That sets me on the right track!

Tim Crowson
Oh thank you! That sets me on the right track!

Cool, glad to help.

I wanted to try to figure out some more advanced mappings using udim tile for instance, but dealing with face-varying attributes means you have to parse the arrays, and it was a little more than I could figure out. A sop-based layer is probably the best-bet in that case.