This was one of the earliest topics I posted when I began using Rhino, and incredibly I’m still struggling with it.
I thought the current CPlane controlled the direction a curve trimmed with, but apparently not in this case? Is that because the “planarity” of the curve takes precedence over the CPlane? And again, no explicit way for the user to control this? (Pascal even at one point made a handy split macro for me, although here I’m doing it manually with trim.)
In no world do I desire the trim result on the left there.
Again, this is all such an unnecessary pain point, wasting my time several times a week for the past seven years.
trim-direction-fail.3dm (73.1 KB)
(Oh, and I don’t need a workaround. The workaround is to join the curves first. Ideally, what I need is for this to never have to happen at all in the first place, saving everyone time and sanity.)