@phaserjs/phaser/math/quaternion/QuatMultiply.js

Phaser 4

import { Quaternion } from "./Quaternion";
export function QuatMultiply(a, b, out = new Quaternion()) {
  const { x: ax, y: ay, z: az, w: aw } = a;
  const { x: bx, y: by, z: bz, w: bw } = b;
  return out.set(ax * bw + aw * bx + ay * bz - az * by, ay * bw + aw * by + az * bx - ax * bz, az * bw + aw * bz + ax * by - ay * bx, aw * bw - ax * bx - ay * by - az * bz);
}