Rhino 6 bug - backface on both sides

Actually that would be exactly backwards since Nurbs surfaces have zero thickness and are used to bound volumes. What they are not is very thin membranes.Think of it as the exterior boundary of a thing.

-Pascal

I do not care what we call it. All I want is to avoid saying that “inner surface of this surface has different color than its outer surface.”

You mean as in backface and frontface as terms you want to avoid?

They are good enough as long as they are clearly defined in the Rhino help file and consistently used throughout the help file.

So, do we all agree there is no display bug?

That said, I’d still like to know why the seam point needs to be flipped, even though the cross-section curves appear to be of the same direction - @pascal?

/Nathan

No we do not, but it does not make much difference. What matters is that there is some kind of a bug - let the programmers figure it out. Your computer displays two mismatched surfaces. My computer displays perfectly matched surfaces.

Hmm? You mean the bottom and top surfaces from the exploded version on the left where I moved the bottom surface to the side, but still on its original plane?

That is what I am doing here.

Except for the backface parts?

Please try the following with your original file :

  • open file
  • set view to Front
  • in Front subobject select top surface anywhere close to the larger cross-section end
  • in Front zoom in on the smaller cross-section end, observe
  • set view to Perspective
  • Zoom in on the smaller cross-section end, observe - the selected subsurface connects to the straight (bottom) part of the cross-setion
  • Zoom in on the larger cross-section end, observe - the selected subsurface connects to the curved (top) part of the cross-section

If you still see the selected subsurface connect to the curved (top) part of the smaller cross-section, please provide screenshots.

/Nathan

P.S. Feel free to explode your original polysurface instead of using subobject select, the procedure is otherwise the same.

I give up - have to go back to work.

i tried that on my rhino 5 mac after rescuing the curves which lets me open rhino 6 curves (not surfaces unfortuntately) and straight out of the box the 2 surfaces cross each other meaning somewhow the curved part managed to flip to the straight part, but if i click on automatic the sweep works as expected. its for sure not a display bug, maybe a bug of some sort idk

This bug was fixed in Rhino 6.2.