/* Copyright (c) 2012 Patrick Ruoff
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 */

#ifndef ROTATION_H
#define ROTATION_H
#include <cmath>
// ----------------------------------------------------------------------------
class Rotation {
	friend Rotation operator*(const Rotation& A, const Rotation& B);
public:
	Rotation() : a(1.0),b(0.0),c(0.0),d(0.0) {}
	Rotation(double yaw, double pitch, double roll) { fromEuler(yaw, pitch, roll); }
	Rotation(double a, double b, double c, double d) : a(a),b(b),c(c),d(d) {}

	Rotation inv(){	// inverse
		return Rotation(a,-b,-c,-d);
	}


	// conversions
	// see http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles
	void fromEuler(double yaw, double pitch, double roll)
	{
		double sin_phi = sin(roll/2.0);
		double cos_phi = cos(roll/2.0);
		double sin_the = sin(pitch/2.0);
		double cos_the = cos(pitch/2.0);
		double sin_psi = sin(yaw/2.0);
		double cos_psi = cos(yaw/2.0);

		a = cos_phi*cos_the*cos_psi + sin_phi*sin_the*sin_psi;
		b = sin_phi*cos_the*cos_psi - cos_phi*sin_the*sin_psi;
		c = cos_phi*sin_the*cos_psi + sin_phi*cos_the*sin_psi;
		d = cos_phi*cos_the*sin_psi - sin_phi*sin_the*cos_psi;
	}

	void Rotation::toEuler(double& yaw, double& pitch, double& roll)
	{
		roll = atan2(2.0*(a*b + c*d), 1.0 - 2.0*(b*b + c*c));
		pitch = asin(2.0*(a*c - b*d));
		yaw =  atan2(2.0*(a*d + b*c), 1.0 - 2.0*(c*c + d*d));
	}

protected:
	double a,b,c,d; // quaternion coefficients
};



Rotation operator*(const Rotation& A, const Rotation& B)
{
	return Rotation(A.a*B.a - A.b*B.b - A.c*B.c - A.d*B.d,	// quaternion multiplication
				    A.a*B.b + A.b*B.a + A.c*B.d - A.d*B.c,
				    A.a*B.c - A.b*B.d + A.c*B.a + A.d*B.b,
				    A.a*B.d + A.b*B.c - A.c*B.b + A.d*B.a);
}
#endif //ROTATION_H