Strange inside-out closed polysrf

I had a file (255 MB) that suddenly started to act very strangely… In the middle of a session I couldn’t fillet edges anymore (the edges didn’t highlight when selecting), some 2D curves would suddenly be invisible (like they would be on a clipping plane) - and extruded closed curves would create an inside-out closed polysurface. The file has some objects from an Inventor (STEP)file in addition to the native Rhino objects. I saved the file under a different name, deleted all objects and made a simple box (exploded and joined to make a polysrf). The resulting polysrf is inside-out:

InsideOutPolySrf.3dm (2.5 MB)

I can send the original (255 MB)file to McNeel if you need more information.


having a super brief glimps i am wildly guessing that is has to do with the display color set to transparent.

edit: ok i guess that is not it, the file indeed reacts strange when i try to add anything else… a polyline would just not show up till i finish for instance.

Hi Philip - it seems to be all pointed the right way but the layer color has 100% transparency,


Yes, inside-out wasn’t correct - I actually meant to say that you can see trough the outside and see the backfaces - and I still didn’t remember that we have this new transparency feature now (which I never use). Sorry for making such a silly mistake (I’m getting old)…
I just wonder how I was able to make the layer transparent in the middle of a modelling session…

Perhaps that coloured square in the layer list should reflect the amount of transparency (with that checkered pattern) instead of showing the normal opaque layer color. I’ll make a new tread with this feature request…


Hmm, I see it already does… but adding the chequered pattern would make it more obvious.