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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 #ifndef Distance_h
30 #define Distance_h
31 
32 #include "platform/PlatformExport.h"
33 
34 namespace blink {
35 
36 // Distance models are defined according to the OpenAL specification:
37 // http://connect.creativelabs.com/openal/Documentation/OpenAL%201.1%20Specification.htm.
38 
39 class PLATFORM_EXPORT DistanceEffect {
40 public:
41     enum ModelType {
42         ModelLinear = 0,
43         ModelInverse = 1,
44         ModelExponential = 2
45     };
46 
47     DistanceEffect();
48 
49     // Returns scalar gain for the given distance the current distance model is used
50     double gain(double distance);
51 
model()52     ModelType model() { return m_model; }
53 
setModel(ModelType model,bool clamped)54     void setModel(ModelType model, bool clamped)
55     {
56         m_model = model;
57         m_isClamped = clamped;
58     }
59 
60     // Distance params
setRefDistance(double refDistance)61     void setRefDistance(double refDistance) { m_refDistance = refDistance; }
setMaxDistance(double maxDistance)62     void setMaxDistance(double maxDistance) { m_maxDistance = maxDistance; }
setRolloffFactor(double rolloffFactor)63     void setRolloffFactor(double rolloffFactor) { m_rolloffFactor = rolloffFactor; }
64 
refDistance()65     double refDistance() const { return m_refDistance; }
maxDistance()66     double maxDistance() const { return m_maxDistance; }
rolloffFactor()67     double rolloffFactor() const { return m_rolloffFactor; }
68 
69 protected:
70     double linearGain(double distance);
71     double inverseGain(double distance);
72     double exponentialGain(double distance);
73 
74     ModelType m_model;
75     bool m_isClamped;
76     double m_refDistance;
77     double m_maxDistance;
78     double m_rolloffFactor;
79 };
80 
81 } // namespace blink
82 
83 #endif // Distance_h
84