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/*
* Copyright (C) 2023 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "Quaternion.h"
#include <cmath>
namespace WebCore {
// Perform a spherical linear interpolation between the two
// passed quaternions with 0 <= t <= 1.
Quaternion Quaternion::slerp(const Quaternion& other, double t)
{
const double kEpsilon = 1e-5;
Quaternion copy = *this;
double cosHalfAngle = copy.x * other.x + copy.y * other.y + copy.z * other.z + copy.w * other.w;
if (cosHalfAngle < 0.0) {
copy.x = -copy.x;
copy.y = -copy.y;
copy.z = -copy.z;
copy.w = -copy.w;
cosHalfAngle = -cosHalfAngle;
}
if (cosHalfAngle > 1)
cosHalfAngle = 1;
double sinHalfAngle = std::sqrt(1.0 - cosHalfAngle * cosHalfAngle);
if (sinHalfAngle < kEpsilon) {
// Quaternions share common axis and angle.
return *this;
}
double halfAngle = std::acos(cosHalfAngle);
double scale = std::sin((1 - t) * halfAngle) / sinHalfAngle;
double invscale = std::sin(t * halfAngle) / sinHalfAngle;
return { copy.x * scale + other.x * invscale, copy.y * scale + other.y * invscale, copy.z * scale + other.z * invscale, copy.w * scale + other.w * invscale };
}
// Compute quaternion multiplication
Quaternion Quaternion::accumulate(const Quaternion& other)
{
return { w * other.x + x * other.w + y * other.z - z * other.y,
w * other.y - x * other.z + y * other.w + z * other.x,
w * other.z + x * other.y - y * other.x + z * other.w,
w * other.w - x * other.x - y * other.y - z * other.z };
}
Quaternion Quaternion::interpolate(const Quaternion& other, double progress, CompositeOperation compositeOperation)
{
if (compositeOperation == CompositeOperation::Accumulate)
return accumulate(other);
return slerp(other, progress);
}
} // namespace WebCore
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