| /* |
| * 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 Computer, 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 "third_party/blink/renderer/platform/audio/distance_effect.h" |
| |
| #include <math.h> |
| #include <algorithm> |
| #include "base/notreached.h" |
| #include "third_party/blink/renderer/platform/wtf/assertions.h" |
| #include "third_party/blink/renderer/platform/wtf/math_extras.h" |
| #include "third_party/fdlibm/ieee754.h" |
| |
| namespace blink { |
| |
| DistanceEffect::DistanceEffect() |
| : model_(kModelInverse), |
| ref_distance_(1.0), |
| max_distance_(10000.0), |
| rolloff_factor_(1.0) {} |
| |
| double DistanceEffect::Gain(double distance) { |
| switch (model_) { |
| case kModelLinear: |
| return LinearGain(distance); |
| case kModelInverse: |
| return InverseGain(distance); |
| case kModelExponential: |
| return ExponentialGain(distance); |
| } |
| NOTREACHED(); |
| return 0.0; |
| } |
| |
| double DistanceEffect::LinearGain(double distance) { |
| // Clamp refDistance and distance according to the spec. |
| double dref = std::min(ref_distance_, max_distance_); |
| double dmax = std::max(ref_distance_, max_distance_); |
| distance = clampTo(distance, dref, dmax); |
| |
| if (dref == dmax) |
| return 1 - rolloff_factor_; |
| |
| // We want a gain that decreases linearly from m_refDistance to |
| // m_maxDistance. The gain is 1 at m_refDistance. |
| return (1.0 - clampTo(rolloff_factor_, 0.0, 1.0) * (distance - dref) / |
| (dmax - dref)); |
| } |
| |
| double DistanceEffect::InverseGain(double distance) { |
| if (ref_distance_ == 0) |
| return 0; |
| |
| // Clamp distance according to spec |
| distance = clampTo(distance, ref_distance_); |
| |
| return ref_distance_ / (ref_distance_ + clampTo(rolloff_factor_, 0.0) * |
| (distance - ref_distance_)); |
| } |
| |
| double DistanceEffect::ExponentialGain(double distance) { |
| if (ref_distance_ == 0) |
| return 0; |
| |
| // Clamp distance according to spec |
| distance = clampTo(distance, ref_distance_); |
| |
| return fdlibm::pow(distance / ref_distance_, -clampTo(rolloff_factor_, 0.0)); |
| } |
| |
| } // namespace blink |