How to rotate model from start to stop slowly smooth in Metal (like Scenekit default sample, or threejs) ?

I'm trying to calculate that the rotation becomes smoother when rotating the model, their movement from fast to slow steadily. I read the documentation and found it related to calculating Angular Speed and Angular Acceleration. Has anyone done it before can share me how to do it in metal ?

Something like example here: https://threejs.org/examples/?q=rotation#misc_controls_arcball

Thanks all.

How to rotate model from start to stop slowly smooth in Metal (like Scenekit default sample, or threejs) ?
 
 
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