/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "Quaternion.h"

#include "Matrix.h"

#include "Tools.h"

#include <algorithm>

#include <ostream>

#include <math.h>

using namespace std;

namespace mozilla {

namespace gfx {

std::ostream&

operator<<(std::ostream& aStream, const Quaternion& aQuat)

{

  return aStream << "< " << aQuat.x << " "  << aQuat.y << " " << aQuat.z << " " << aQuat.w << ">";

}

void

Quaternion::SetFromRotationMatrix(const Matrix4x4& m)

{

  // see http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToQuaternion/index.htm

  const Float trace = m._11 + m._22 + m._33;

  if (trace > 0.0) {

    const Float s = 0.5f / sqrt(trace + 1.0f);

    w = 0.25f / s;

    x = (m._32 - m._23) * s;

    y = (m._13 - m._31) * s;

    z = (m._21 - m._12) * s;

  } else if (m._11 > m._22 && m._11 > m._33) {

    const Float s = 2.0f * sqrt(1.0f + m._11 - m._22 - m._33);

    w = (m._32 - m._23) / s;

    x = 0.25f * s;

    y = (m._12 + m._21) / s;

    z = (m._13 + m._31) / s;

  } else if (m._22 > m._33) {

    const Float s = 2.0 * sqrt(1.0f + m._22 - m._11 - m._33);

    w = (m._13 - m._31) / s;

    x = (m._12 + m._21) / s;

    y = 0.25f * s;

    z = (m._23 + m._32) / s;

  } else {

    const Float s = 2.0 * sqrt(1.0f + m._33 - m._11 - m._22);

    w = (m._21 - m._12) / s;

    x = (m._13 + m._31) / s;

    y = (m._23 + m._32) / s;

    z = 0.25f * s;

  }

}

} // namespace gfx

} // namespace mozilla