Finding inside or outside facing primitives

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Hi all,

I'm having a hard time explaining my question properly but here goes!

Perhaps it will be better to explain it with an example - if I had an empty carboard box, I want to find the inside facing surfaces and the outside facing surfaces, on a horizontal plane so I can manipulate them separately. In Houdini, I can easily find them using the extrudeFrontSeam or extrudeBackSeam groups after extrusion to give thickness, but I lose these groups after doing a bevel.

After an extrude, I can easily determine inside and outside facing prims:


But after a bevel, how do I find them here?
Edited by RooiJakkals - Feb. 17, 2023 20:25:06

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Hi, you can try two attribute promote sops. 1st after the extrude, 2nd after the bevel. Depending on the topology and what sops you are using, you can often (not always) keep point groups through a chain. I've attached a hip and screenshot.

Rob

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Group_Promote.hiplc (163.6 KB)
Group_Promote.jpg (91.7 KB)

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even without those Group Promote nodes the primitive extrude* groups are preserved after polybevel
Tomas Slancik
FX Supervisor
Method Studios, NY
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Yeh, I'd normally use this to promote seams/edges but they were looking for inside/outside so prims made more sense. In this example, the promote isn't needed but it may be useful to know for other scenarios.
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Here's another version promoting the extrude seams/edges.

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Group_Promote_edges.hiplc (163.6 KB)
Group_Promote_edges.jpg (117.1 KB)

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Hey Robsdesign/tamte,

Thank you so much, you just saved me a huge headache! This is so simple slick and clean, where everything else I tried turned into a clunky mess. Had no idea group promote was for these group type conversions.

I actually started off wrong, first doing an inset, then extruding upwards and losing control of the sides - it was part of a much bigger solution. This pushed me in the right direction.

Thanks again for the support!!
Edited by RooiJakkals - Feb. 19, 2023 09:20:13
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