TweenCurves failure

In the attached, TweenCurves fails to do anything (V5, V6, or 7Wip). Select start and end curves and the command just quits. I can’t see anything really wrong with the curves themselves… They are polycurves composed of 2 joined degree 1 NURBS curves. If I run SimplifyCrv, it simplifies them into polycurves composed of two joined polylines. Then TweenCurves works. (If I run SimplifyCrv again, they become pure polylines - so there is also a bug in SimplifyCrv, it should do this on the first run, will report this separately.)

TweenFail.3dm (46.4 KB)

Note also that TweenCurves - once it does work - creates degree 3 NURBS curves as results from 2 input polylines. IMO, that’s not right either. Running SimplifyCrv on the result turns the degree 3 NURBS curves into polylines…

I noticed also that if you explode the left curve, the long one, then join it again
The tweencurves works. But exploding the right curve alone and join it doesn’t
Change anything. The other two MatchMethod methods inside the TweenCurves command,
None and Sample points, will preserve the degree 1. None in the case of your file gives a better
Result. But for you, i guess, both are less satisfactory than the Refit option
In matter of smooth transition.

It works with Pufferfish TweenTwoCurves component (some parts don’t seem exact halfway but this is because of the control point distribution). GH native tween curves doesn’t fail but gets pretty off results. They both keep the degree though.

Hi Mitch - thanks, I see that. SimplifyCrv also lets it work.