/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is:
 *   OGF/Graphite: Geometry and Graphics Programming Library + Utilities
 *   Copyright (C) 2000 Bruno Levy
 *   Contact: Bruno Levy
 *      <levy@loria.fr>
 *      ISA Project
 *      LORIA, INRIA Lorraine,
 *      Campus Scientifique, BP 239
 *      54506 VANDOEUVRE LES NANCY CEDEX
 *      FRANCE
 */

/** \file
 * \ingroup freestyle
 */

#include "normal_cycle.h"
#include "matrix_util.h"

namespace Freestyle::OGF {

//_________________________________________________________

void NormalCycle::begin()
{
  M_[0] = M_[1] = M_[2] = M_[3] = M_[4] = M_[5] = 0;
}

void NormalCycle::end()
{
  double eigen_vectors[9];
  MatrixUtil::semi_definite_symmetric_eigen(M_, 3, eigen_vectors, eigen_value_);

  axis_[0] = Vec3r(eigen_vectors[0], eigen_vectors[1], eigen_vectors[2]);

  axis_[1] = Vec3r(eigen_vectors[3], eigen_vectors[4], eigen_vectors[5]);

  axis_[2] = Vec3r(eigen_vectors[6], eigen_vectors[7], eigen_vectors[8]);

  // Normalize the eigen vectors
  for (int i = 0; i < 3; i++) {
    axis_[i].normalize();
  }

  // Sort the eigen vectors
  i_[0] = 0;
  i_[1] = 1;
  i_[2] = 2;

  double l0 = ::fabs(eigen_value_[0]);
  double l1 = ::fabs(eigen_value_[1]);
  double l2 = ::fabs(eigen_value_[2]);

  if (l1 > l0) {
    ogf_swap(l0, l1);
    ogf_swap(i_[0], i_[1]);
  }
  if (l2 > l1) {
    ogf_swap(l1, l2);
    ogf_swap(i_[1], i_[2]);
  }
  if (l1 > l0) {
    ogf_swap(l0, l1);
    ogf_swap(i_[0], i_[1]);
  }
}

//_________________________________________________________

}  // namespace Freestyle::OGF