mirror of
https://github.com/thestk/stk
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103 lines
2.6 KiB
C++
103 lines
2.6 KiB
C++
/***************************************************/
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/*! \class Drone
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\brief STK "drone" plucked string model.
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This class implements a simple plucked string
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physical model based on the Karplus-Strong
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algorithm.
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This is a digital waveguide model, making its
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use possibly subject to patents held by
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Stanford University, Yamaha, and others.
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There exist at least two patents, assigned to
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Stanford, bearing the names of Karplus and/or
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Strong.
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by Perry R. Cook and Gary P. Scavone, 1995 - 2002.
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*/
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/***************************************************/
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#include "Drone.h"
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Drone :: Drone(MY_FLOAT lowestFrequency)
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{
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length = (long) (Stk::sampleRate() / lowestFrequency + 1);
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loopGain = (MY_FLOAT) 0.999;
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delayLine = new DelayA( (MY_FLOAT)(length / 2.0), length );
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loopFilter = new OneZero;
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noise = new Noise;
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envelope = new ADSR();
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envelope->setAllTimes(2.0, 0.5, 0.0, 0.5);
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this->clear();
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}
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Drone :: ~Drone()
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{
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delete delayLine;
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delete loopFilter;
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delete envelope;
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delete noise;
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}
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void Drone :: clear()
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{
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delayLine->clear();
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loopFilter->clear();
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}
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void Drone :: setFrequency(MY_FLOAT frequency)
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{
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MY_FLOAT freakency = frequency;
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if ( frequency <= 0.0 ) {
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cerr << "Drone: setFrequency parameter is less than or equal to zero!" << endl;
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freakency = 220.0;
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}
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// Delay = length - approximate filter delay.
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MY_FLOAT delay = (Stk::sampleRate() / freakency) - (MY_FLOAT) 0.5;
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if (delay <= 0.0) delay = 0.3;
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else if (delay > length) delay = length;
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delayLine->setDelay(delay);
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loopGain = 0.997 + (freakency * 0.000002);
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if ( loopGain >= 1.0 ) loopGain = (MY_FLOAT) 0.99999;
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}
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void Drone :: pluck(MY_FLOAT amplitude)
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{
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envelope->keyOn();
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}
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void Drone :: noteOn(MY_FLOAT frequency, MY_FLOAT amplitude)
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{
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this->setFrequency(frequency);
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this->pluck(amplitude);
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#if defined(_STK_DEBUG_)
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cerr << "Drone: NoteOn frequency = " << frequency << ", amplitude = " << amplitude << endl;
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#endif
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}
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void Drone :: noteOff(MY_FLOAT amplitude)
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{
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loopGain = (MY_FLOAT) 1.0 - amplitude;
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if ( loopGain < 0.0 ) {
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cerr << "Drone: noteOff amplitude greater than 1.0!" << endl;
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loopGain = 0.0;
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}
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else if ( loopGain > 1.0 ) {
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cerr << "Drone: noteOff amplitude less than or zero!" << endl;
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loopGain = (MY_FLOAT) 0.99999;
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}
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#if defined(_STK_DEBUG_)
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cerr << "Drone: NoteOff amplitude = " << amplitude << endl;
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#endif
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}
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MY_FLOAT Drone :: tick()
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{
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// Here's the whole inner loop of the instrument!!
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lastOutput = delayLine->tick( loopFilter->tick( delayLine->lastOut() * loopGain ) + (0.005 * envelope->tick() * noise->tick()));
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return lastOutput;
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}
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