Simple utility for jme3 to convert cartesian to spherical coordinates and vice-versa

CoordinateUtil.java

/*
 * Copyright (c) 2016 Sebastian Teumert (<http://teumert.net>)
 * 
 * Permission is hereby granted,  free of charge, to any person obtaining a copy 
 * of this software and associated documentation files (the "Software"), to deal 
 * in the Software without restriction,  including without limitation the rights 
 * to use,  copy, modify,  merge,  publish, distribute,  sublicense, and/or sell 
 * copies  of  the Software,  and to  permit  persons  to whom  the  Software is 
 * furnished to do so, subject to the following conditions:
 *
 * The above  copyright notice  and this permission notice  shall be included in 
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED  "AS IS",  WITHOUT WARRANTY OF ANY KIND,  EXPRESS OR 
 * IMPLIED,  INCLUDING  BUT  NOT  LIMITED TO  THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
 * IN NO EVENT SHALL  THE AUTHORS OR  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
 * DAMAGES  OR  OTHER  LIABILITY,  WHETHER IN  AN ACTION  OF  CONTRACT,  TORT OR 
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE 
 * OR OTHER DEALINGS IN THE SOFTWARE.
 */
package net.teumert.jme3.math;

import com.jme3.math.Vector3f;


/**
 * <p>
 * 	Utility class to convert cartesian coordinates to spherical (polar)
 * 	coordinates and vice-versa.
 * </p>
 * 
 * <p>
 * 	Can also be used to derive geographical coordinates, if needed, by using 
 * 	the conventions/conversions:
 * </p>
 * 
 * <pre>
 * 	Mathematics              Geography/Cartography
 * 	r,  radial distance      R + h, radius + altitude
 * 	φ,p polar angle          90 - φ, colatitude (latitude = 90 - colatitude)
 * 	θ,a azimuthal angle      λ, longitude
 * 	radians                  degrees = radians * 360 / 2π
 * </pre>
 * 
 * <p>
 * 	Formula are as described at
 * 	<a href="http://mathworld.wolfram.com/SphericalCoordinates.html">
 * 		Weisstein, Eric W. "Spherical Coordinates." 
 * 		From MathWorld--A Wolfram Web Resource. 
 * 	</a>
 * </p>
 * 
 * <p>
 * 	This class assumes the polar axis is the z-axis, and the equatorial plane is
 * 	the XY plane.
 * </p>
 * @author Sebastian Teumert
 *
 */
public class CoordinateUtil {
	
	/**
	 * Converts cartesian to (spherical) polar coordinates. See class
	 * description for conventions.
	 * 
	 * @param x cartesian x-ordinate
	 * @param y cartesian y-ordinate
	 * @param z cartesian z-ordinate
	 * @return {@link Vector3f} with the spherical coordinates (r, a , p)
	 */
	public static Vector3f cartesianToSpherical (float x, float y, float z) {
		float r = (float) Math.sqrt(x * x + y * y + z * z);
		float a = (float) Math.atan2(y, x);
		float p = (float) Math.acos(z / r);
		return new Vector3f(r, a, p);
	}
	
	/**
	 * Converts cartesian to (spherical) polar coordinates. See class
	 * description for conventions.
	 * 
	 * @param v {@link Vector3f} in the cartesian (x, y ,z) form
	 * @return {@link Vector3f} in spherical (r, a , p) form
	 */
	public static Vector3f cartesianToSpherical (Vector3f v) {
		return cartesianToSpherical(v.x, v.y, v.z);
	}
	
	/**
	 * Converts polar (spherical) co-ordinates in the form (r, a, p) to
	 * cartesian ones.
	 * 
	 * @param r radial distance
	 * @param a azimuth angle
	 * @param p polar angle
	 * @return {@link Vector3f} in cartesian (x, y, z) form
	 */
	public static Vector3f sphericalToCartesian(float r, float a, float p) {
		float x = (float) (r * Math.cos(a) * Math.sin(p));
		float y = (float) (r * Math.sin(a) * Math.sin(p));
		float z = (float) (r * Math.cos(p));
		return new Vector3f(x, y, z);
	}
	
	/**
	 * Converts polar (spherical) co-ordinates in the form (r, a, p) to
	 * cartesian ones.
	 * 
	 * @param v {@link Vector3f} in spherical (r, a , p) form
	 * @return {@link Vector3f} in cartesian (x, y, z) form
	 */
	public static Vector3f sphericalToCartesian(Vector3f v) {
		return sphericalToCartesian(v.x, v.y, v.z);
	}
}