/*
 * 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 Copyright (C) 2018 by Blender Foundation.
 * All rights reserved.
 */

/** \file
 * \ingroup bke
 */

#pragma once

#include "BKE_multires.h"
#include "BLI_math_vector.h"
#include "BLI_utildefines.h"

BLI_INLINE void BKE_multires_construct_tangent_matrix(float tangent_matrix[3][3],
                                                      const float dPdu[3],
                                                      const float dPdv[3],
                                                      const int corner)
{
  if (corner == 0) {
    copy_v3_v3(tangent_matrix[0], dPdv);
    copy_v3_v3(tangent_matrix[1], dPdu);
    mul_v3_fl(tangent_matrix[0], -1.0f);
    mul_v3_fl(tangent_matrix[1], -1.0f);
  }
  else if (corner == 1) {
    copy_v3_v3(tangent_matrix[0], dPdu);
    copy_v3_v3(tangent_matrix[1], dPdv);
    mul_v3_fl(tangent_matrix[1], -1.0f);
  }
  else if (corner == 2) {
    copy_v3_v3(tangent_matrix[0], dPdv);
    copy_v3_v3(tangent_matrix[1], dPdu);
  }
  else if (corner == 3) {
    copy_v3_v3(tangent_matrix[0], dPdu);
    copy_v3_v3(tangent_matrix[1], dPdv);
    mul_v3_fl(tangent_matrix[0], -1.0f);
  }
  else {
    BLI_assert_msg(0, "Unhandled corner index");
  }
  cross_v3_v3v3(tangent_matrix[2], dPdu, dPdv);
  normalize_v3(tangent_matrix[0]);
  normalize_v3(tangent_matrix[1]);
  normalize_v3(tangent_matrix[2]);
}