I have been writing a RhinoCommon (c#) plugin to convert the native file format of Gravity Sketch into native Rhino Geometry.
Due to the limited nature of available features in OpenNURBS, we are working on a Rhino Import plugin, rather than a .3dm export plugin.
The issue we have come across is that we are trying to perform a SweepOneRail where you specify multiple profiles along the curve to match our geometry creation. This works perfectly for any NURBSCurve we throw at it, and any set of profiles.
However, as soon as you close the curve, SweepOneRail.PerformSweep silently returns null breps, regardless of any other parameters.
Is there a reason for this? or some way to get more detailed information as to why it is failing?