I instancing a bunch of splines on a curved geometry (a big pipe). Not geometry, but specifically a splines.
The problem starts when i convert those splines to mesh, because it looks like instanced splines tilt are doesnt correspond to instance rotation.
So i think it is possible to fix by setting the appropriate curve tils for each instance, but i dot really get how to calculate those angle?
can u pls provide blend file or node tree? thx
Here’s the problem:
Until we realize instances, the tilt of curve (or tilt/rotation of Arc node) are perfectly fine. For make it more clear i set angle to less than 360 degree so we can clearly see - its align perfectly.
Unfortunately, in the moment we realize intances, curves tilt (or Arc tilt?) will be ruined:
Notice how some of the Arc rotated in the wrong direction (if we rotate initial mesh (“donut”) Arc (or curves tilt?) will become even more random and unpredictable:
For a reason i want to keep Arc orientation in the correct way without unwanted random rotations.
I also need this to being able to add random noise which will be unique for all spines, so i need to realize them anyway before converting them to mesh.
Oh man… I don’t think you’re going to like the answer…
…basically you have to make an instance with Geometry to Instance, make as many copies as you need with Duplicate Elements in Instance mode… realize that then do what you wanna do with them (noise, curve-to-mesh, etc.) at the origin and then use the Duplicate Index as input to a Sample Index to read the curve data to then do a Set Position…
It completely breaks the convenience of using instances in the first place but I don’t know of a more convenient workaround. Sorry.
Hope that helps.
I was thinking exactly in that way, i.e. creating a duplicates and place them where i need, but have no idea how to achieve that (even wasnt sure its possible with duplicated geo).
Many thanks! 
