/cvmfs/atlas.cern.ch/repo/sw/ASG/AnalysisBase/2.4.31/GeoPrimitives/GeoPrimitives/EulerAnglesHelpers.h

/*
 * eigen_migration
 * EulerAnglesHelpers.cpp
 *
 *  Created on: Feb 11, 2014
 *      Author: rbianchi <Riccardo.Maria.Bianchi@cern.ch>
 *
 */

#ifndef _GEOPRIMITIVES_EULERANGLESHELPERS_H
#define _GEOPRIMITIVES_EULERANGLESHELPERS_H

#include "GeoPrimitives/GeoPrimitives.h"

#include "CLHEPtoEigenEulerAnglesConverters.h"

namespace Amg {

inline Amg::Vector3D getPhiThetaPsi(Amg::RotationMatrix3D mat, int convention = 0)
{
    double phi;
    double theta;
    double psi;

    Amg::Vector3D ea; // euler angles vector

    // using Z-X-Z convention: (2,0,2) == "Z,X,Z"
    if (convention == 0) {
        ea = mat.eulerAngles(2, 0, 2); // (using Z-X-Z convention) // DEFAULT
    }
    // using Z-Y-Z convention: (2,1,2) == "Z,Y,Z"
    else {
        ea = mat.eulerAngles(2, 1, 2); // (using Z-Y-Z convention)
    }

    // convert the values from Eigen convention to CLHEP convention
    ea = convert_EigenEulerAngles_to_CLHEPPhiThetaPsi( ea, convention );

    phi = ea[0];
    theta = ea[1];
    psi = ea[2];

    Amg::Vector3D phiThetaPsi_angles;
    phiThetaPsi_angles(0) = phi;
    phiThetaPsi_angles(1) = theta;
    phiThetaPsi_angles(2) = psi;

    return phiThetaPsi_angles;

} // end of getPhiThetaPsi()







/* Set the Phi angle of a rotation matrix,
 * leaving Theta and Psi unaltered.
 *
 * Actually it returns a new rotation matrix
 * built with the new Phi angle, and with the
 * Theta and Psi angles taken from the original matrix.
 *
 * N.B.
 * if "convention = 0" --> "Z-X-Z" convention ==> DEFAULT!!
 * if "convention = 1" --> "Z-Y-Z" convention
 *
 * N.B.!!
 * for normal usage, use the default notation (simply leave it empty, or use convention=0),
 * or, alternatively, be sure to use the same convention in both setPhi() and getPhiThetaPsi().
 *
 *
 */
inline Amg::RotationMatrix3D setPhi(Amg::RotationMatrix3D mat, double angle, int convention = 0)
{


    Amg::Vector3D phi_theta_psi;


    // using Z-X-Z convention: (2,0,2) == "Z,X,Z". ==>  DEFAULT!
    if (convention == 0) {
        phi_theta_psi = getPhiThetaPsi(mat, 0); // using Z-X-Z ((2,0,2) convention // DEFAULT
    }
    else { // using Z-Y-Z convention: (2,1,2) == "Z,Y,Z"
        phi_theta_psi = getPhiThetaPsi(mat, 1); // using Z-Y-Z ((2,1,2) convention
    }

    double phi = phi_theta_psi(0);
    double theta = phi_theta_psi(1);
    double psi = phi_theta_psi(2);


    /*
     * set a new Phi angle, from user's settings
     */
    phi = angle;

    /*
     * get Eigen Euler angles from CLEHP style Phi, Theta, Psi
     */
    Amg::Vector3D clhep_phiThetaPsi(phi, theta, psi); // a vector with CLHEP angles
    Amg::Vector3D eigen_euler_angles;
    // converting the CLHEP angles to Eigen angles
    if (convention == 0) { // using Z-X-Z convention: (2,0,2) == "Z,X,Z". ==>  DEFAULT!
        eigen_euler_angles = convert_CLHEPPhiThetaPsi_to_EigenEulerAngles(clhep_phiThetaPsi, 0); // using Z-X-Z ((2,0,2) convention // DEFAULT
    }
    else { // using Z-Y-Z convention: (2,1,2) == "Z,Y,Z"
        eigen_euler_angles = convert_CLHEPPhiThetaPsi_to_EigenEulerAngles(clhep_phiThetaPsi, 1); // using Z-Y-Z ((2,1,2) convention
    }

    /*
     * create a new rotation matrix from AngleAxis
     *
     * N.B.!!
     * to match CLHEP results,
     * we have to invert the order of the rotation operations,
     * compared to the order in CLHEP.
     * The matrix here below is equal to:
     * ---
     * CLHEP::HepRotation localRot;
     * localRot.rotateZ(angC);
     * localRot.rotateY(angB);
     * localRot.rotateZ(angA);
     * ---
     *
     */

    if (convention == 0) { // using Z-X-Z convention: (2,0,2) == "Z,X,Z". ==>  DEFAULT!
        mat = Amg::AngleAxis3D(eigen_euler_angles(0), Amg::Vector3D::UnitZ())
        * Amg::AngleAxis3D(eigen_euler_angles(1), Amg::Vector3D::UnitX())
        * Amg::AngleAxis3D(eigen_euler_angles(2), Amg::Vector3D::UnitZ());
    }
    else { // using Z-Y-Z convention: (2,1,2) == "Z,Y,Z"
        mat = Amg::AngleAxis3D(eigen_euler_angles(0), Amg::Vector3D::UnitZ())
        * Amg::AngleAxis3D(eigen_euler_angles(1), Amg::Vector3D::UnitY())
        * Amg::AngleAxis3D(eigen_euler_angles(2), Amg::Vector3D::UnitZ());
    }

    return mat;

} // end of SetPhi()




} // end of namespace Amg


#endif

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