Rotation to Axis Angle Node

Documentation
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I can’t find any documentation about this node on the manual.

This node seems to output always the Y axis and the relative angle.
So I have some remarks:

  • wouldn’t it be more correct to call the output socket “Y Axis” instead of “Axis”?
  • it would be ideal to add a vector input socket, so you have control on the axis that you can use as angle reference
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No, it would not be correct to call it that. It is converting from Eulere rotation to rotation about an axis. See the documentation for the inverse, Axis Angle to Rotation Node.

If you take the Rotation to Axis Angle node and plug it into the Axis Angle to Rotation Node you will find it behaves as you would expect.

The point of having something like an Axis Angle is to be able to rotate about arbitrary axes in the world.

The reason for its existence it to be able to take a euler rotation value that is more intuitive to understand, then do weird things to it like project it onto an axis, or take its cross product with an arbitrary value:

20241231_11h02m35s_grim
20241231_11h02m35s_grim1440×606 104 KB

Adding the node to the documentation probably would be beneficial in case someone else comes across it and wonders what its for (a large part of why I am commenting here).

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Thanks for the clarification,
Now I see the purpose

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I think rotations are stored as quaternions anytime the purple socket is used, but I could be mistaken.