_OrientOnCrv unexpected base point

Rhino Rhino for Windows
1

2023-09-22_OrientOnCrv.3dm (30.2 KB)

I want to copy the red curve in the same direction as the original red curve on the cyan curve.
image

Therefore I _OrientOnCrv.

I select the red curve.
Then I set the base point to the upper end of the red curve.
Then I select the cyan orientation curve.

The copies go to the outside of the cyan curve.
Flip doesn’t change it.

Ok, then I invert the direction of the red curve.
No change when using _OrientOnCrv.

Finally, to get the desired result, I have set the base point to the lower end of the red curve.
Then it works ok.

Is there a misunderstanding on my part regarding the base point?

2

This is confusing… Also the perpendicular option…

If you use the option Base point OnCurve it works as expected.

image
image1477×990 57.4 KB

3

Yes, strange, I already selected the base point…
…I think something is not quite right.

I tested in V5-8, it works always the same (Flip option is not there in V5).
So my first idea was that it is my misunderstanding.

Any clarification, perhaps @Gijs or @pascal or so?

4

Hi Charles - yeah, It is confusing and not always very intuitive - the problem is, the orientation plane uses the current Cplane as a reference - in this case, if you flip the front CPlane so that Y is down, it does what you expect. I agree this could/should be better, I’ll see what we can do. My guess is a fix would entail more user input, more like OrientOnSrf, to establish a base plane since the object to be oriented is not necessarily oriented ‘correctly’ to begin with - it can be anywhere.

ArrayCrv does ‘the right thing’ here… so it should be perfectly possible.

-Pascal

5

@pascal
Thanks for the explanation.
Once understood, the behavior makes more sense.

Good to know it’s not just my stupidity :wink: