Use keyframes to customize interpolation errors

Using keyframes for custom interpolation errors is using gltf’s CubicSplineTrackInterpolant
The correct situation should be to rotate back and forth between the start and end points, not to return to the starting point and spin for a while…
Below is an online demo

How to make a non-linear animation

reference GLTFLoader:实现基本的 CUBICSPLINE 支持 by donmccurdy ·拉取请求 #12885 ·mrdoob/three.js (github.com)
GLTFLoader 三次样条插值完全支持 takahirox ·拉取请求 #12907 ·mrdoob/three.js (github.com)