Problems with Ribbon Offset WIP7

after watching Kyle’s great video about ribbon offset, I wanted to try that to make a mould, but run into problems I can’t figure out. In the middle of the curve the offset curve changes direction, and the sweep looks very wild.

I then tried to rebuild the edge, but got a strange entry for tolerances: 1e-05, and when I changed that to 0.001, that didn’t help either. I checked the normals on the surfaces, but they were okay.

Screen Shot 2020-02-10 at 17.20.05

I am aware, that a lot of modelling has been done on this surface … might that be the problem?

Thanks in advance, I’ll attack the file. Best regards - Jan

ribbon-offset-challenge.3dm (3.0 MB)

@janneuffer RibbonOffset is a viewport dependent command since the curve it makes is projected to the C-Plane that is active when running the command. In your case you can either rotate the curve to be aligned better with the cplane or create another cplane that is more aligned to your curve.

In the below example I have oriented your curve to allow for proper projection to the Front C-Plane.

Hopefully that helps.

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Great – yes that worked! I missed that the command is viewport dependant, but now I’ve got.
Thank you so much!! Jan

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On command, it would be interesting to be able to perform a variable ribbon offset, adding along the curve some handles to which you can set a different width.

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If I draw a flat poly-curve, the command is not executed from the external part of the figure (if I choose the internal side, the command is executed).

Could you check it out?

Hi @davide76,

Can you provide a 3dm file that contains the geometry that the RibbonOffset is not working with?


– Dale

Ribbon offset.3dm (144.4 KB)

@davide76 thanks i’ve the logged the issue here.

This problem occurs only for closed (polylines) flat curves.
If the polyline is not flat it works on both sides (inside and outside).