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/*
* Copyright (C) 2010 Google 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.
* 3. Neither the name of Apple Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "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 OR ITS 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"
#if ENABLE(WEB_AUDIO)
#include "Distance.h"
#include <algorithm>
#include <math.h>
namespace WebCore {
DistanceEffect::DistanceEffect() = default;
double DistanceEffect::gain(double distance) const
{
// don't go beyond maximum distance
distance = std::min(distance, m_maxDistance);
// if clamped, don't get closer than reference distance
if (m_isClamped)
distance = std::max(distance, m_refDistance);
switch (m_model) {
case DistanceModelType::Linear:
return linearGain(distance);
case DistanceModelType::Inverse:
return inverseGain(distance);
case DistanceModelType::Exponential:
return exponentialGain(distance);
}
ASSERT_NOT_REACHED();
return 0.0;
}
double DistanceEffect::linearGain(double distance) const
{
auto clampedRolloffFactor = std::clamp(m_rolloffFactor, 0.0, 1.0);
// We want a gain that decreases linearly from m_refDistance to
// m_maxDistance. The gain is 1 at m_refDistance.
return (1.0 - clampedRolloffFactor * (distance - m_refDistance) / (m_maxDistance - m_refDistance));
}
double DistanceEffect::inverseGain(double distance) const
{
return m_refDistance / (m_refDistance + m_rolloffFactor * (distance - m_refDistance));
}
double DistanceEffect::exponentialGain(double distance) const
{
return pow(distance / m_refDistance, -m_rolloffFactor);
}
} // namespace WebCore
#endif // ENABLE(WEB_AUDIO)
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