Rhino 7 vs Rhino 6 circle offset error (Grasshopper)

in Rhino 6 circle offset maintain circlulare shape correctly, however when I offset circle in Rhino 7 it deforms into ellips then a twisted ellips.
Rhino 7, something is wrong circle does not offset to circle. instead, it offset to ellips shape.
in plane xy it offset correctly but in other planes in mess up the offset.

In Rhino 6, circle offset to circle in all planes.

I even tried copy paste the GH definition from Rh6 to Rh7 and it gave the same wrong results.
could anyone try this definition on his Rhino 7 and check if it’s my machine problem or it is a bug in Rhino 7.

deformed circle shape in Rhino 7 after offset

thank you in advance

Can you upload the definition?

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GH_Rhino_7.gh (10.3 KB)

GH_Rhino_6.gh (7.2 KB)

What definition? I don’t see a GH file?

And I don’t see any plane input to Offset?

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in XY plane, the circle offset is correct as shown in the picture

however when I offset a circle curve in a custom plane the shape deforms as shown in the picture

offset curve component

thank you in advance

Does supplying a plane to Offset make any difference in R7?



Yes this one does work, I wonder why Rhino 6 offset circle correctly without needing to Plane Normal component.

thank you for the quick reply. I could use some other workaround in Rhino 7 probably

The default “P” plane is World XY, and seeing the situation from above actually sort of make more sense:
2021-01-12 02_37_40-Window
grasshopper is really trying to make the offset in respect of such plane. (for an inner offset…)

Not sure if it was done a change to work this way…

Every red line here tends to be parallel to XY plane.

On rhino 6, even if you manually set XY plane for your tilted circles, the plane is completely ignored.

One could interpret this is actually an improvement…
No idea.

Edit: lame gif!


2021-01-12 02_53_17-Window

Rhino 7
2021-01-12 02_52_46-Window

ooook… :sweat_smile:

For now it means we are forced to input the correct plane every time we are making offset of a non-XY curve…

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Thank you for the explanation, that does make sense. non XY-plane offset does need a guide plane to offset correctly in Rhino 7. \

have a good day

Would it be fair to call this a GH7 quirk?


All - thrown onto the heap as RH-62293.

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Or is it an old quirk (R5 and R6) that has been “fixed” in R7? Quirky for sure.

This reminds me of another quirk I’ve seen in R6. As I recall, Surface Split failed in R5 if the curves were not pulled to the surface first but R6 seems to have that pull-to-surface built in? It works even when the splitting curves don’t touch the surface.

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I would see it as both, bug and perk…

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