Odd upVector/rotation along linear Spline

I’ll showcase this with SplineAnimate to simplify things.

In my examples, the animated object rolls in an odd, unexpected way.
You can see the roll as well as the rotation in the inspector.

If all knots have the same rotation:

If each knot roughly points towards the next knot:

If all knots have the same rotation BUT instead of pitch, there is yaw:

So yaw behaves as expected, pitch does not.

If instead of linear, we use bezier but with a tiny tangent:

This almost behaves as expected. The rotation is shifting a tiny bit though.

Am I misunderstanding how this should function?

This occurs with Evaluate and it appears to be the upVector that is changing between knots in an unexpected way.

I’ve also found Splines generally quite difficult to work with. Here’s an example of a bug which certainly doesn’t help: 2024-12-03 10-44-57.mp4 - Google Drive

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Hello,

If possible please report this through the Bug Reporter and make sure to attach your Project so that it could be looked at by CQA and if identified and reproduced then perhaps fixed if it’s a bug in the Editor.

You can do so by following these steps:

  1. Open your project and attempt to reproduce the issue, to verify it’s still happening
  2. Open the Bug Reporter through the Editor (Help → Report A Bug)
  3. Write the details as to what steps need to be taken to visually see the bug happening and what are the expected results
  4. Also please attach a link to this Discussions thread into the description

I’ve sent the bug report.

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