Geo Nodes - Euler alignments flipping on curve with 90degree angles

Support Modeling
1

Hi,

I’m working on a pipe generator and am ironing out the very last kink. I’m instancing objects on curves however I am experiencing some unexpected behaviour where the instances often flip and don’t follow the set rotation alignments at perfect 90 degree angles. However, if you slightly nudge a vertex position slightly the orientations seem to fix themselves and behave as expected. This isn’t ideal as the user has to constantly nudge verts every time they extrude the edge.

In a nutshell, I have an original curve that I am splitting up into segments to instance objects on the points. Because I am splitting up the curve into segments, I am copying the original tangent / normals to each of the separated curve segments (I have a feeling this might be the issue?). The current instance rotations are driven by first aligning Euler to the tangent, followed by an axis of the curve normal.

Here is a scene with some examples of the problem occurring with my setup if anyone would be kind enough to take a look.
WIP_scene_08.blend (4.6 MB)

Thanks!

2

grafik
grafik1888×762 202 KB

:wink:

3

Ah right! Thanks for flagging that! I actually disconnected the “captured” tangent from the original curve while debugging to see if using the standard curve tangent node made any difference (It didnt). It seems that if I plug the captured tangent into both the vector and rotation sockets it fixes the issue.

I’m not exactly sure why that works however. In the past leaving the rotation blank on the first Euler node and then stacking extra Euler nodes to create more constraints has worked fine. Good to know going forward though.

Thanks again for all the help

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