Bug: Simple merge coplanar faces failure


MergeAllCoplanarFaces produces invalid results in this simple case.
If I offset those 3 faces one by one (instead of joined polysurface), boolean union results, and then merge coplanar faces, it works.

merge coplanar.3dm (125.7 KB)

Yeah, that looks buggy to me somehow - V6 does not have this problem.

Hi Jakub -

I wasn’t able to reproduce this from scratch but I see that here as well with your file.
I also see that when I open that file, VisualARQ fires up. When I launch Rhino in Safe Mode and then open your file and go through the procedure, all goes well.
I’m recategorizing this for now.
@fsalla - could you take a look?

Hi @wim,

I haven’t been able to reproduce this issue neither with nor without VisualARQ loaded :confused:

@Czaja I haven’t been able to reproduce this error either. It doesn’t look like an issue related to VisualARQ. What makes you think it’s a problem of VisualARQ? Does that happen to you if VisualARQ is not loaded? What Rhino version are you using? What Absolute tolerance units are you using?

Hi, it was moved from Rhino Windows to the VisualARQ category by @wim. I don’t think it is plugin related because even in Safe Mode Rhino 7 produces invalid polysurface. Another thing, as @Helvetosaur noticed, in RH6 MergeAllFaces produces good results.

I’m using Rhino 7.2.20343 and my absolute tolerances were set to 0.01. Offset is made by 0.3 meters.
Now as I dig deeper, it looks that rising absolute tolerance to 0.1 solves the problem - but of course that is not the answer, because it’s hard to imagine to work in meters with 10 cm tolerance.

Offset comparsion (before MergeAllCoplanarFaces command):

@wim it happens in plain rhino 7.2 as well, see attached:

Merging one trimmed and one untrimmed face gives an invalid BrepMergeAllCoPlanarFacesBug.3dm (91.1 KB)

Thanks, Gijs, for also taking a look.
I’m not sure what the instructions are for that file. I ran MergeAllCoplanarFaces on both objects and got valid polysurfaces here.

I’m running an internal build of 7.4 here now but I’m sure that I was using 7.3 when I looked into that 16 days ago. The 7.3 version is now available as a service release candidate. Could you install that and check if that solves things?

Moving this thread back to Rhino.

yes, perfect, works again as expected in 7.3

I guess that explains things : )
Thanks again, Gijs!