Offset fails in Grasshopper but works when invoked manually

Hi,

for some curves offsets will fail in Grasshopper but work when invoked manually with the same settings (tolerance, corner type, etc.). What’s the difference between the native command and Grasshopper (or Rhino.Common)?

OffsetFailure.gh (14.5 KB)
Minimal example. To reproduce, bake the curve and offset it with the arguments from in the screenshot.

Rhino for Mac Version 7 (7.9.21196.07002, 2021-07-15)
See also: Offset Curve Failure

It’s fairly obvious what happens with negative offset distances if you zoom in and look at discontinuities (white points on original curve, blue points on offset curve). Slider range is from -0.05 to -0.05.


OffsetFailure_2021_Jul19a.gh (17.3 KB)

No problem with positive distances:

Interesting to see what happens with “larger” negative values:

It’s fairly obvious what happens with negative offset distances if you zoom in and look at discontinuities

Thank you for your reply. I am afraid it is not obvious to me, what are the discontinuities telling me?

My point was that the manual command appears to perform some magic to deal with these difficulties. Is there a way to reproduce the behaviour in Grasshopper?