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/*
* Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
* Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#include "third_party/blink/renderer/platform/transforms/rotation.h"
#include "third_party/blink/renderer/platform/geometry/blend.h"
#include "ui/gfx/geometry/quaternion.h"
#include "ui/gfx/geometry/transform.h"
namespace blink {
using gfx::Quaternion;
namespace {
const double kAngleEpsilon = 1e-4;
Quaternion ComputeQuaternion(const Rotation& rotation) {
return Quaternion::FromAxisAngle(rotation.axis.x(), rotation.axis.y(),
rotation.axis.z(), Deg2rad(rotation.angle));
}
gfx::Vector3dF NormalizeAxis(gfx::Vector3dF axis) {
gfx::Vector3dF normalized;
if (axis.GetNormalized(&normalized))
return normalized;
// Rotation angle is zero so the axis is arbitrary.
return gfx::Vector3dF(0, 0, 1);
}
Rotation ComputeRotation(Quaternion q) {
double cos_half_angle = q.w();
double interpolated_angle = Rad2deg(2 * std::acos(cos_half_angle));
gfx::Vector3dF interpolated_axis =
NormalizeAxis(gfx::Vector3dF(q.x(), q.y(), q.z()));
return Rotation(interpolated_axis, interpolated_angle);
}
} // namespace
bool Rotation::GetCommonAxis(const Rotation& a,
const Rotation& b,
gfx::Vector3dF& result_axis,
double& result_angle_a,
double& result_angle_b) {
result_axis = gfx::Vector3dF(0, 0, 1);
result_angle_a = 0;
result_angle_b = 0;
// We have to consider two definitions of "is zero" here, because we
// sometimes need to preserve (as an interpolation result) and expose
// to web content an axis that is associated with a zero angle. Thus
// we consider having a zero axis stronger than having a zero angle.
bool a_has_zero_axis = a.axis.IsZero();
bool b_has_zero_axis = b.axis.IsZero();
bool is_zero_a, is_zero_b;
if (a_has_zero_axis || b_has_zero_axis) {
is_zero_a = a_has_zero_axis;
is_zero_b = b_has_zero_axis;
} else {
is_zero_a = fabs(a.angle) < kAngleEpsilon;
is_zero_b = fabs(b.angle) < kAngleEpsilon;
}
if (is_zero_a && is_zero_b)
return true;
if (is_zero_a) {
result_axis = NormalizeAxis(b.axis);
result_angle_b = b.angle;
return true;
}
if (is_zero_b) {
result_axis = NormalizeAxis(a.axis);
result_angle_a = a.angle;
return true;
}
double dot = gfx::DotProduct(a.axis, b.axis);
if (dot < 0)
return false;
double a_squared = a.axis.LengthSquared();
double b_squared = b.axis.LengthSquared();
double error = std::abs(1 - (dot * dot) / (a_squared * b_squared));
if (error > kAngleEpsilon)
return false;
result_axis = NormalizeAxis(a.axis);
result_angle_a = a.angle;
result_angle_b = b.angle;
return true;
}
Rotation Rotation::Slerp(const Rotation& from,
const Rotation& to,
double progress) {
double from_angle;
double to_angle;
gfx::Vector3dF axis;
if (GetCommonAxis(from, to, axis, from_angle, to_angle))
return Rotation(axis, blink::Blend(from_angle, to_angle, progress));
Quaternion qa = ComputeQuaternion(from);
Quaternion qb = ComputeQuaternion(to);
Quaternion qc = qa.Slerp(qb, progress);
return ComputeRotation(qc);
}
Rotation Rotation::Add(const Rotation& a, const Rotation& b) {
double angle_a;
double angle_b;
gfx::Vector3dF axis;
if (GetCommonAxis(a, b, axis, angle_a, angle_b))
return Rotation(axis, angle_a + angle_b);
Quaternion qa = ComputeQuaternion(a);
Quaternion qb = ComputeQuaternion(b);
Quaternion qc = qa * qb;
if (qc.w() < 0) {
// Choose the equivalent rotation with the smaller angle.
qc = qc.flip();
}
return ComputeRotation(qc);
}
} // namespace blink
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