OLD | NEW |
| (Empty) |
1 /* | |
2 * Copyright (C) 2010 Google Inc. All rights reserved. | |
3 * | |
4 * Redistribution and use in source and binary forms, with or without | |
5 * modification, are permitted provided that the following conditions | |
6 * are met: | |
7 * | |
8 * 1. Redistributions of source code must retain the above copyright | |
9 * notice, this list of conditions and the following disclaimer. | |
10 * 2. Redistributions in binary form must reproduce the above copyright | |
11 * notice, this list of conditions and the following disclaimer in the | |
12 * documentation and/or other materials provided with the distribution. | |
13 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of | |
14 * its contributors may be used to endorse or promote products derived | |
15 * from this software without specific prior written permission. | |
16 * | |
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY | |
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED | |
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | |
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY | |
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND | |
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
27 */ | |
28 | |
29 #include "platform/audio/Distance.h" | |
30 | |
31 #include <math.h> | |
32 #include <algorithm> | |
33 #include "platform/wtf/Assertions.h" | |
34 #include "platform/wtf/MathExtras.h" | |
35 | |
36 namespace blink { | |
37 | |
38 DistanceEffect::DistanceEffect() | |
39 : model_(kModelInverse), | |
40 ref_distance_(1.0), | |
41 max_distance_(10000.0), | |
42 rolloff_factor_(1.0) {} | |
43 | |
44 double DistanceEffect::Gain(double distance) { | |
45 switch (model_) { | |
46 case kModelLinear: | |
47 return LinearGain(distance); | |
48 case kModelInverse: | |
49 return InverseGain(distance); | |
50 case kModelExponential: | |
51 return ExponentialGain(distance); | |
52 } | |
53 NOTREACHED(); | |
54 return 0.0; | |
55 } | |
56 | |
57 double DistanceEffect::LinearGain(double distance) { | |
58 // Clamp refDistance and distance according to the spec. | |
59 double dref = std::min(ref_distance_, max_distance_); | |
60 double dmax = std::max(ref_distance_, max_distance_); | |
61 distance = clampTo(distance, dref, dmax); | |
62 | |
63 if (dref == dmax) | |
64 return 1 - rolloff_factor_; | |
65 | |
66 // We want a gain that decreases linearly from m_refDistance to | |
67 // m_maxDistance. The gain is 1 at m_refDistance. | |
68 return (1.0 - clampTo(rolloff_factor_, 0.0, 1.0) * (distance - dref) / | |
69 (dmax - dref)); | |
70 } | |
71 | |
72 double DistanceEffect::InverseGain(double distance) { | |
73 if (ref_distance_ == 0) | |
74 return 0; | |
75 | |
76 // Clamp distance according to spec | |
77 distance = clampTo(distance, ref_distance_); | |
78 | |
79 return ref_distance_ / (ref_distance_ + clampTo(rolloff_factor_, 0.0) * | |
80 (distance - ref_distance_)); | |
81 } | |
82 | |
83 double DistanceEffect::ExponentialGain(double distance) { | |
84 if (ref_distance_ == 0) | |
85 return 0; | |
86 | |
87 // Clamp distance according to spec | |
88 distance = clampTo(distance, ref_distance_); | |
89 | |
90 return pow(distance / ref_distance_, -clampTo(rolloff_factor_, 0.0)); | |
91 } | |
92 | |
93 } // namespace blink | |
OLD | NEW |