Method polar

jni/venus/vec3.h:123–133

* give the vector v a spherical coordinate system(rho, theta, phi) view. * http://en.wikipedia.org/wiki/Spherical_coordinate_system * r ≥ 0, 0° ≤ θ ≤ 180° (π rad), 0° ≤ φ < 360° (2π rad) * However, the azimuth φ is often restricted to the interval (−180°, +180°], * or (−π, +π] in radians, instead of [0, 360°). This is the standard * convention for geographic longitude. * * @return ve

	 */
	//FIXME
	vec3<T> polar() const
	{
		T _rho = length(), _theta = 0, _phi = 0;
		if(!isZero<T>(_rho))
		{
			_theta = std::acos(z/rho);
//			_theta == 0 means vector parallel to y axis in OpenGL
			_phi = (isZero<T>(theta))?  0 : std::atan2(y, x);
		}
		return vec3<T>(_rho, _theta, _phi);
	}

	vec3<T> project(vec3<T>& direction, bool normalized = false) const
	{