Hello,
I’m trying to orientate some objects manually along a curve. I would like to orientate them not using the global coordinate system but based on the previous object (orientation = previous object orientation + delta angle). And I would like to orientate them using only 2 axis if possible (rotation around x and z)

I did something which seems to work when the curve is in the XY plane (global rotation at the bottom part of the curve: x=0, y=0, z=90°-> horizontal) or in the ZY plane (x=90°, y=0, z=0 -> horizontal). See the attached picture (paint is my friend).

But when I try at 45° between these two plans, it doesn’t work (x=90°, y=0, z=90° at the bottom part).

How does the quaternion work? Why does the orientation of the object tend to deviate in this case? Is it possible to reach the right orientation using only 2 axes?
Thank you for your help, if you have any tips…