AlexAegis/loreplotter

import { Euler, Quaternion, Spherical, Vector3 } from 'three';

const look = new Vector3();

export function quaternionToSpherical(q: Quaternion, r = 1): Spherical {
    const s = new Spherical();
    new Euler().setFromQuaternion(q);
    look.set(0, 0, 1);
    look.applyQuaternion(q);
    look.normalize();
    if (Math.abs(look.x) < 0.001) {
        look.x = 0.001;
    }
    s.set(1, Math.acos(look.z / r), Math.atan2(look.y, look.x));
    return s;
}