ExtendSrf on trimmed surfaces - major regression

ExtendSrf on at least some trimmed surfaces has a major problem in Work In Progress
(8.0.23094.11475, 2023-04-04). Attempting to extend an edge a large amount results in the other edges extending by large amounts. V7 works as expected. Example with blue the original trimmed surface, green the result of ExtendSrf:
Extend Trimmed Srf V8.3dm (9.3 MB)

1 Like

This bug appears to be the cause of the problem reported in "_ExtendSrf" command weird behaviour in Rhino 8 WIP (Bug) - #10 by gian The surface in that thread is interesting because it was imported and while trimmed the edges coincide with the untrimmed edges.

Someone from McNeel needs to get this major regression into YouTrack with priority. ExtendSrf is a commonly used command, and it needs to work properly with trimmed surfaces. If it already in the system please let us know.

Should we call someone specific in you opinion?

I was going to wait to see if someone responds by Monday. McNeel participation in the forum appears to be a bit light today. Today and this week is a holiday for many in the US.

Yes let’s wait. Right now I was just wondering who could be the one to ask to.

thanks @davidcockey I’ve run into this myself as well.

RH-74088 ExtendSrf extends surface in more than one direction


I’m having similar issues on 3 point planar surfaces built in Rhino:

The case in the screen grab was trying to extend the untrimmed RH edge of the plane by 20mm. It appears that the command is untrimming the whole surface and then extending everything but the selected edge by an far larger amount.
Work around is to duplicate the edges you want to keep for trimming before doing the extend and untrim the surface first so it actually extends the bit you want.

Same behavior as I reported.