Surfaces Disappear After Mirroring

If I copy an object, all surfaces appear when rendering the viewport. If I mirror the object and render the viewport, the front surfaces are not visible, while back surfaces are. If I rotate the view, surface visibility changes depending on whether the surface rotates to the back or front. All inner surfaces are always visible. This problem just cropped up in the last week. Using Version 5 SR6 64-bit from 9/18/2013.

Tangent Laser.3dm(1.6 MB)

This sounds like you have backfaces set up to be invisible in your display mode… Go into Options>View>Display Modes>Rendered and find the “Backface settings” - see if it isn’t set to “Cull backfaces”. If so, change to “Use front face settings”, that should fix it.


I’ve actually started to see this more often as well. It has been there for quite a while on heavier files when the backface is set to something dissimilar to front face (say single color for all backfaces) on non-closed surface / polysurfaces, but more recently have been seeing this happen on mirrored closed polysurfaces as well (and I think I saw it in a display mode where the backface used the front face settings).


Mitch and Sam, Thank you both for the quick replies. The back face settings are all set to front face, so that’s not the problem. Again, as Sam points out, it happens only on mirrored closed polysurfaces, but not on the originals or copied ones. I will send this off to Rhino Tech Support.

I am also having this issue, with closed polysurfaces, after installing SR6 RC1.
If I explode/join my object it reverts to normal, but then history is lost.

Here is a reply from Rodrigo Bárcena, Technical Support in Spain. I tried it and it works.

Hi John,

I can see this is happening here too. I’m setting a bug report for our developers.

A work-around :
You have created the part using extrude, right?
As you know, extrusions are handled differently from other objects. If you explode the part and join all surfaces again , the part will become a closed polysurface and all surfaces will be visible.


Rodrigo Bárcena

Bug report item:

These are not visible to the public yet.


What is the link that was added to the last reply?

That link is to the bug as tracked in our internal bug tracking system. Eventually, the idea is that you (the public) will be able to see these, perhaps comment on them or even report bugs, but all that has not been implemented and I don’t know if there is a timeline for it. We attach the bug items to these so that when and if it all works as planned , you’d be able go see what the status is on the bug from the link.


Ahhh… OK. Thank you for explaining.

Hi all,

Comin all the way from 2019 with Rhino V5 and finding a similar issue.

The attached jpeg (“rhino_hollow block glitch”) explains it all, but to put it shortly, I’m having the same issue TangentLaser started with, but with mirroring blocks.

Has anyone found a solution to this yet? Also, I understand Rhino is deep in V6 and I’m using an old version, but maybe there was a solution/patch that corrects the error…?

Affected .3dm file attached as well as a jpeg that shows my exact version of Rhino.

rhino%20version rhino_hollow block glitch.3dm (400.8 KB)