I have been trying to wrap my mind around the SQUAD algorithm (sometimes called "Spherical Cubic Interpolation", sometimes called "Spherical Quadratic Interpolation").
If I understand it correctly it's supposed to smooth out rotations using 4 quaternions that are in sequential order in an animation with rotation keyframes.
Now I do get SLERP and I claim to have a fairly good visualization of the hypersphere and how quaternions describe it's "surface" (does the term "surspace" exist?)
However I was confused as to why the SQUAD algorithm should work. To understand it better I simply took some paper and drew the algorithm in 0.2 steps using 2d points and LERP, pretending the paper is the surface (surspace?) of the unit hypersphere. The curves I am getting look like they are exact mirror images of what I think I actually want to have.
Maybe I am still lacking some fundamental knowledge of quaternions. I have attached a scan of my drawings:
So, my concrete questions:
- Am I doing something wrong?
- Am I misunderstanding what SQUAD does or what it is for?
- Am I fundamentally misunderstanding quaternions and the curves I get are actually super fine?