Flow command mirrors objects weirdly

Hey :slight_smile:
I want to create a band, that has the same thing printed on it, like The amazon packaging tape for example. After some playing around i thought i was where i wanted to be, just to realize the objects on the bottom are mirrored.
This is what i want to be arranged around the curve:


This is the target curve:


Those are my settings:


This is the result:
As you can see, the ones on the bottom are rotated around instead of facing down/away from the band.


It sure has something to do with the points, where the curve goes “negative” to close the loop. But how can I avoid this? Flow along surface might be the alterative, but i also would want it to work that way…

Any suggestions? Thanks in advance :slight_smile:

FlowIssue_SD.3dm (10.8 MB)

I get this, which appears to be correct to my eye-

two things I changed. I marked the crvend on the target so I knew where to pick from the parent to the target curve.

and I made the parent curve match the target curve length, and added some more objects to the curve.

check this file to see if it’s what you want.
FlowIssue_SD_kfix.3dm (19.9 MB)

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… you may want to use a surface and flowAlongSrf instead ?

Thanks, that worked out the way I wanted :slight_smile:

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Like I wrote, I wanted to get behind what the reason for the issue is. I like to know the roots of the issue and how the software “ticks” in order to solve similar issues later on :slight_smile:
If something behaves (in my eyes) weird i need know if its my own fault or a bug.

But yes, flow along surface would have been the easier way from the beginning

fast and dirty without claiming this is valid for a scientific paper:

Flow based on curves - will not have enough information to define a unique and human expected transformation in space for all constellations: As soon as a curve has 0 curvature / is straight there is only a tangent, but not a frame / normal. Though the spacial orientation is estimated by (suspected / guess) World Z-Axis - and this might not correspond to our human expectations.
There are other command that suffer from this limitation - check _orient with a 180-degree turn.

it s not how the software ticks but more that a cross product can be a tiny or zero-length vector - and cad is always some juggling of tolerances… which might fail close to 180 degree here.

a surface without collapsed edges will have a proper curvature / normal definition at all positions. thats why flowAlongSrf wins here.

kind regards - tom

Thanks, that helps me understand the limitations a little better :slight_smile: