Automated Way to Achieve _BlendCrv with G4 Continuity?


Grasshopper or RhinoCommon currently do not provide access to G3/G4 continuity as stated here:

However, I need to blend a lot of curves with G4, which can’t be done manually.

Here are the things I tried, which (I) failed:

  1. Trying to reverse-engineer the G4 blending by distributing 4 control points linearly along the curves tangents at the ends, which are to be blended. The 8 control points are then used in connection with a curve of polynomial degree of 9. This however slightly deviates from Rhinos more sophisticated solution.

The black lines are the curves to be blended, in red the tangents are shown and in green the _BlendCrv with G4 is shown. The upper curve is a straight line, all 4 control points are on the red tangent. The lower curve is not a line, the 4 control points are not on the tangent.

  1. Recording a Macro. Usually, you write what you would click in the command-line and enter values accordingly. _BlendCrv however, uses a popup-window, which leaves the user in the dark how to do things. Is this possible?


request for G3/G4 is listed as
RH-70602 Blend two curves with G3 continuity in Grasshopper