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[Allen Chou]

Hi, all:

I wrote a post about swing-twist decomposition & interpolation of quaternions.

It is an alternative to spherical linear interpolation (slerp) and normalized linear interpolation (nlerp).

Representing two orientations using quaternions, slerp & lerp interpolate between the quaternions along the "shortest arc" on a 4D hypersphere. Although that feels mathematically ideal, sometimes it produces noticeable unwanted orientational sways in 3D.

Swing-twist interpolation (sterp) is an alternative to slerp & lerp, and can be used to mitigate orientational sways when interpolating quaternions.

For more details including derivation with properly formatted formulas, proof, and animated examples, please see:
http://allenchou.net/2018/05/game-math-swing-twist-interpolation-sterp/

[ThemsAllTook]

Neat! Bookmarked in case I run into a situation where slerp isn't satisfying enough. Thanks for sharing.

[Crimsontide]

Neat! Bookmarked in case I run into a situation where slerp isn't satisfying enough. Thanks for sharing.

Agreed.  At this moment I'm not playing with my Quaternion code, but its something I'll look at down the line when I get time...