In the image above, all curves are 2D planar curves. The red curve is the desired result. It was produced using a default application of the interactive command BlendCrv. In C#, all my efforts to duplicate the red curve turn out looking like the blue curve. I’ve tried everything I can think of to change the result and it just keeps returning the same result every time. Here’s the code snippet I’m using:
rhCrvBlend = Curve.CreateBlendCurve(rhCrvParent, rhCrvParent, BlendContinuity.Tangency);
I’ve tried all sorts of variations on the theme using a single parent curve and multiple parent curves, and I get the same result in Rhino 5 32-bit, Rhino 5 64-bit, and Rhino 6. I’ve tried changing the BlendContinuity to Curvature and it only makes the sharp corner less conspicuous. I don’t understand why RhinoCommon is “throwing” the control points so far away from the parent curves. When I interactively construct the BlendCrv, the control points do not extend past the midpoint of the created curve. I’ve tried scaling the model by a factor of 100 and I get the same results, so it’s not a matter of tolerances or some weird snap setting (I tried disabling Osnap, Ortho, GridSnap, and SmartTrack in code, too, just in case).