CurveRibbonOffset Method 
Name  Description  

RibbonOffset(Double, Double, Point3d, Vector3d, Double) 
Offsets a closed curve in the following way: pProject the curve to a plane with given normal.
Then, loose Offset the projection by distance + blend_radius and trim off selfintersection.
THen, Offset the remaining curve back in the opposite direction by blend_radius, filling gaps with blends.
Finally, use the elevations of the input curve to get the correct elevations of the result.
 
RibbonOffset(Double, Double, Point3d, Vector3d, Double, Curve, Surface) 
Offsets a closed curve in the following way: pProject the curve to a plane with given normal.
Then, loose Offset the projection by distance + blend_radius and trim off selfintersection.
THen, Offset the remaining curve back in the opposite direction by blend_radius, filling gaps with blends.
Finally, use the elevations of the input curve to get the correct elevations of the result.
 
RibbonOffset(Double, Double, Point3d, Vector3d, Double, Double, Double) 
Offsets a closed curve in the following way: pProject the curve to a plane with given normal.
Then, loose Offset the projection by distance + blend_radius and trim off selfintersection.
THen, Offset the remaining curve back in the opposite direction by blend_radius, filling gaps with blends.
Finally, use the elevations of the input curve to get the correct elevations of the result.
