ExtendSrf fails, OffsetCrvOnSrf fails

See attached model:
CP_2019-07-05_ExtendFail.3dm (56.9 KB)

Using ExtendSrf I can’t even select a srf edge.
In V5 it works.

OffsetCrvOnSrf fails as well.
Both in V6 and V5.


Hi Charles - my guess is the singularities at each end are making it difficult.


that’s why is not recommendable to make surfaces converging to a point. if you make a tiny trim at both ends and shrink it, you will be able to extend the surfaces and the offset will work better.

Instead of trimming the surface, you can extend it by doing the following:

  1. Use “Split edge” to split the desired surface edge in two random areas.
  2. Now use “Extend surface” and click on the middle area of the surface edge (between the two split spots). For some reason, only then Rhino 6 will magically consider the middle surface edge as if it was a part of a 4-sided surface, hence it will allow you to click it to extend the surface.
  3. That’s it. Once you finish the extend command, Rhino 6 will automatically merge the split edge.

That is a very good approach and works perfect.
Thanks for the hint.

I still wonder why V5 lets me extend and V6 not.
Bug or by design?

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