ExtendSrf Bug

This is an old bug and its been reported before, but its an especially egregious example of just how bad the quality control is at the Mcneel company.

Extending the edge on the enclosed model creates a Bad Object.
ExtendSrf_bug.3dm (49.3 KB)

But worse than that, Rhino fails to identify it as a Bad Object. After extending you can run DupBorder and then the Bad Object warning pops up. I’d like someone at McNeel explain how the borders of a polysurface can be a Bad Object but the Polysurface itself is deemed not to be bad?

This bug has been around ever since they made it possible to extend surfaces that are joined. That would be a nice feature if it could be trusted to not trash the users geometry.
So the prudent user has to continue to do it the old school way of extracting the surface then extending then joining it back to where it came from. If the user can do it correctly, why can’t McNeel?

Hello- thanks, - as far as I can see this works in our current builds here.



I installed the latest Rhino (8.5.24047.13001) and Extending the surface at that edge still creates a Bad Object. And in addition Rhino still fails to identify the object as invalid.
Rhino does however identify the border curve (DupBorder) as an invalid curve. Seems like a no-brainer to identify an object with an invalid border as an invalid object.

This bug has been around since around 2018 and the obvious reason for a dumb bug like this to persist for so many years is because the built in mechanism for checking error fails to do its job. I have seen this bug reported by others, so that mechanism for catching errors isn’t working very well either.