Is there any official documentation or very good tutorial about quaternions?

I find it difficult with quaternions even rotate a single direction…

I don’t think it’s possible for a human to work with quaternions directly unless you’re a genius =)

You can always convert a quat to a rotator, calculate what you need, convert the result back to a quat and let the engine do the rest for you.

As Tuerer already said, these are really unintuitive to use. You can play around with https://quaternions.online/ this tool, if you like.

A really good explanation in my opinion also covering some history is here: Quaternions - YouTube - just theory, not covering any practical use in Unreal.

Alright thanks I see they are from another dimension ahahhaha get it ? ahahahahaha

I’m also having problems with the quaternions, at the control rig I couldn’t find a option to convert them to rotator, which would make everything easier, as I wish to use the original ankle Z axis, applying changes only to X and Y axis in order to match the surface angle.

Edit: I found a transform to Euler at control rig functions, but it is not working properly. By the single fact of converting to Euler then back to quaternion changes the result.

Edit2: Apparently I needed to alter the order of the Euler to XZY and use the original X axis, and Y and Z from the normals in order to work properly.