function Spherical( radius, phi, theta ) {

		this.radius = ( radius !== undefined ) ? radius : 1.0;
		this.phi = ( phi !== undefined ) ? phi : 0; // up / down towards top and bottom pole
		this.theta = ( theta !== undefined ) ? theta : 0; // around the equator of the sphere

		return this;

	}
@author bhouston / http://clara.io
@author WestLangley / http://github.com/WestLangley

Ref: https://en.wikipedia.org/wiki/Spherical_coordinate_system

The poles (phi) are at the positive and negative y axis.
The equator starts at positive z.