Tested in Rhino 7.38, 8.33 and 9.0.26230 beta, Windows x64. Same result in all three. What happens BlendCrv with Continuity set to G4 on both ends returns a degree-9 curve that satisfies G0, G1, G2 and G3 to machine precision, but misses the fourth-order condition. d²κ/ds² differs across the joint …

Nobody’s gonna read that AI stuff. These automated dubious “bug reports” are murdering huge chunks of open-source code because no one wants to deal with the deluge.

Hi @Teo , I am looking at this. Thanks, – Dale

disclaimer: i just skimmed over your code, but could not really make sense of it. direct your LLM towards: • “Bell-Polynomial”, • the works of Veltkamp • setup a system of Beziér shape functions and evaluate them at the start and end • setup a linear system of equations and solve for each end. …

[image] Teo: In absolute terms the miss is small: on a 2.5 m blend, moving a single control point by 0.055 mm would satisfy G4 exactly. What is the practical relevance of this? When is G4 continuity relevant? What manufacturing method ofor arbitrary shaped curves/surfaces has accuracy better…

Hi everyone, I’ve been working on a Python script—assisted by AI—to test continuity between curves, as I noticed that the BlendCrv command allows for continuity up to G4, whereas Rhino’s GCon command only detects up to G2. Through testing and cross-verification, I concluded that the G4 setting does…

Hi @Teo , I’ve logged an issue so developer can look into this. GCon should test for G4/G4 : RH-98013 https://discourse.mcneel.com/t/blendcrv-with-g4-continuity-produces-a-curve-that-is-only-g3/222098 Rhino's "BlendCrv" allows for G3 and even G4 continuity. image.png However, the "GCon…

BlendCrv with G4 continuity produces a curve that is only G3

Rhino Rhino for Windows

brian (Brian Gillespie) September 8, 2026, 10:45pm 8

RH-98013 is fixed in Rhino BETA

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BlendCrv with G4 continuity produces a curve that is only G3

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