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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 WebCore {
     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 
     52     ModelType model() { return m_model; }
     53 
     54     void setModel(ModelType model, bool clamped)
     55     {
     56         m_model = model;
     57         m_isClamped = clamped;
     58     }
     59 
     60     // Distance params
     61     void setRefDistance(double refDistance) { m_refDistance = refDistance; }
     62     void setMaxDistance(double maxDistance) { m_maxDistance = maxDistance; }
     63     void setRolloffFactor(double rolloffFactor) { m_rolloffFactor = rolloffFactor; }
     64 
     65     double refDistance() const { return m_refDistance; }
     66     double maxDistance() const { return m_maxDistance; }
     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 WebCore
     82 
     83 #endif // Distance_h
     84