2 BUGS with Match curve

Rhino Rhino for Windows
1

Just upgraded to the latest Rhino 7 SR20 (7.20.22178.1001, 2022-06-27) and figured out that there are two bugs with the ! _Match command on curves:

  1. The G2 curvature match does not work with the simple lofted surface (created with “Loft” between the two white curves) attached in the 3dm file below. G1 works, however. The interesting part is that if I build a curve at a steep angle relative to the target surface edge, then G2 works. Looks like the problem comes from the very tiny angle difference between the curve and the target surface edge, but that does not explain why G1 works while G2 won’t.
    If I set the curve to G1 and finish the command, then run it again, this time around Rhino will apply G2 just as expected.

  2. Upon canceling the “Match” command, the curve to be matched remains yellow, ignoring both the “Cancel” and “Cancel all” commands. That happens only if the control points of the curve were already turned on. To remove the yellow marking from the curve, I’m forced to select the latter and then deselect it with the mouse pointer.

G2 does not work with Match curve.3dm (137.3 KB)

Both of those bugs are shown in my video:

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2

Or move the third control point on the line (the control point which affects curvature but not tangency at the end by the surface). That changes the curvature difference at the end of the curve but not the tangency difference. After the change G2 curvature match works.

It looks to me like a combination of tangency and curvature difference between the curve and the target is within a tolerance so Match for curvature ignores it. I would consider it a bug but the developer may consider it a feature.

3

To me it’s a clear indication of a bug rather than a feature, because the G2 matching refuses to do its job. When G2 is checked by the user, Rhino should always provide a proper G2 as expected. However, G2 works if I rotate the same curve at extra 0,1 degrees sideways.

The issue with the curve staying yellow is also quite strange to me.

4

Thanks, I’ll check.
RH-69296 Match: Selection highlight glitch
RH-69295 Match fails for G2

-Pascal

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RH-69296 is fixed in Rhino 7 Service Release 21

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