In RhinoCommon and Grasshopper, InterpolatedCurve must have a odd degree.
In Rhino,even degree interpolation curves can be created.
Is there any way to call the curve creation algorithm of the _InterpCrv command？
I studied this part, but it didn’t seem to solve my confusion.After looking at the information, what I said about interpolated point curve made me even more confused.
I constructed a third-degree interpolated point curve with six points in gh, but in rhino it showed that he had eight EditPt.
Obviously, interpolation points and edit points are similar, but not consistent.
I then used the same points to construct a fourth-degree curve, but it showed a degree of 5 in Rhino.
Using the same six points, use _InterpCrv
command:，I can indeed construct a fourth-degree curve.
These confusing and inconsistent results make me wonder what kind of rules InterpCrv follows to construct the nurbs curve.
At the moment doing even-degree interpolation is not supported through RhinoCommon or Grasshopper. This is because some situations do not allow even degree interpolation, and the interpolation is performed at odd degree (min. 3), followed by degree elevation after the fact. One of these cases is a persistently closed curve (also known as a periodic curve).
I think the SDK could follow the same approach as the command and allow even degree interpolation. I have made an enhancement feature request to do this:
Looking forward to enhancing !!
期待修复！！！
The issue https://mcneel.myjetbrains.com/youtrack/issue/RH-81632 has been resolved and will make it into Rhino 8 SR 8.