DistanceSimulator.h

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//
//  DistanceSimulator.h -- Specification of the DistanceSimulators
//  See the copyright notice and acknowledgment of authors in the file COPYRIGHT
//  Created by Jorge Castellanos on 6/23/06. Hacked 8/09 by STP.
//

#ifndef DISTANCE_SIMULATOR_H
#define DISTANCE_SIMULATOR_H
#include "SpatialSource.h"

#include "CSL_Core.h"
#include "CPoint.h"

namespace csl {

class IntensityAttenuationCue;
class AirAbsorptionCue;

/// Only handles single sound sources because objects have different positions. 
/// Two objects can't ocuppy the same position, and usually distance cues go before the 
/// panning, so handling multiple sources by one Distance simulator, would producde a multi-channel
/// object, where the positions aren't dynamic anymore.

class DistanceSimulator : public SpatialSource {
public:
    DistanceSimulator(UnitGenerator &source); // A UGen without position information. In this case, the distance simulator is the spatial source.
    DistanceSimulator(SpatialSource &source);
    ~DistanceSimulator();

    virtual void nextBuffer(Buffer & outputBuffer, unsigned outBufNum) throw (CException);
                                        /// Returns wether the sound source position changed since last block call.
    virtual bool positionChanged();

protected:
                // SoundSource ... it refers to its input UGen, but with the knowledge of its position within a space.
//  SpatialSource *mSource;     // list of spatial inputs
    IntensityAttenuationCue *mIntensityCue;
    AirAbsorptionCue *mAirAbsorptionCue;

}; 

/// Pure Abstract Base Class for all distance cues. 
/// A DistanceCue subclass is just an algorithm that modifies a signal based on the distance from the listener.
/// Distance Cues should hold their state, so when "process" is called they can modify the signal buffer given.
/// When "compute" is called is usually due to a change in distance, so if anything has to be re-calculated, it's done.

class DistanceCue {
public:
    DistanceCue() { };
    virtual ~DistanceCue() { };
    
    virtual void compute(float distance) = 0;
    virtual void process(Buffer &inputBuffer) = 0;

}; 

/// Sound attenuation due to increasing distance. This "Base" Class uses the inverse square law.
/// Subclass for other methods.

class IntensityAttenuationCue : public DistanceCue {
public:
    IntensityAttenuationCue() { };
    virtual ~IntensityAttenuationCue() { };

    virtual void compute(float distance);   
    virtual void process(Buffer &aBuffer);
    
protected:  
    float mGain;

};

/// Simulates the frequency dependent air absorption using a one pole/zero lowpass filter.

class AirAbsorptionCue : public DistanceCue {
public:
    AirAbsorptionCue();
    virtual ~AirAbsorptionCue();

    virtual void compute(float distance); ///< Calculate the filter coefficients.
    virtual void process(Buffer &aBuffer); ///< Process each sample in the buffer, applying the filter.
    
protected:  
    float mBCoeff;
    float mACoeff[2];
    float mPrevOutput;
    float mPrevInput;

};

//class AirAbsorptionCue : public DistanceCue {
//public:
//  AirAbsorptionCue();
//  virtual ~AirAbsorptionCue();
//
//  virtual void compute(float distance);   
//  virtual void process(Buffer &aBuffer);
//  
//protected:    
//  float mBCoeff[3];
//  float mACoeff[3];
//  float mPrevOutputs[3];
//  float mPrevInputs[3];
//
//};

}

#endif