gecko-dev/gfx/2d/Quaternion.cpp

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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* 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