code: function Cylindrical( radius, theta, y ) {
  
  	this.radius = ( radius !== undefined ) ? radius : 1.0; // distance from the origin to a point in the x-z plane
  	this.theta = ( theta !== undefined ) ? theta : 0; // counterclockwise angle in the x-z plane measured in radians from the positive z-axis
  	this.y = ( y !== undefined ) ? y : 0; // height above the x-z plane
  
  	return this;
  
  }
docs: @author Mugen87 / https://github.com/Mugen87
  
  Ref: https://en.wikipedia.org/wiki/Cylindrical_coordinate_system