_randomVector3OnSphere (base, radius, scale) {
		const z = 2 * Math.random() - 1;
		const t = 6.2832 * Math.random();
		const r = Math.sqrt(1 - z * z);
		const vec = new THREE.Vector3(r * Math.cos(t), r * Math.sin(t), z);

		vec.multiplyScalar(radius);

		if (scale) {
			vec.multiply(scale);
		}

		vec.add(base);

		return vec;
	}
Create a new THREE.Vector3 instance and project it onto a random point
on a sphere with radius `radius`.

@param  {THREE.Vector3} base
@param  {Number} radius
@param  {THREE.Vector3} scale

@private

@return {THREE.Vector3}