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https://github.com/thestk/stk
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101 lines
2.5 KiB
C++
101 lines
2.5 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 - 2010.
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*/
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/***************************************************/
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#include "Drone.h"
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namespace stk {
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Drone :: Drone( StkFloat lowestFrequency )
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{
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length_ = (unsigned long) ( Stk::sampleRate() / lowestFrequency + 1 );
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loopGain_ = 0.999;
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delayLine_.setMaximumDelay( length_ );
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delayLine_.setDelay( 0.5 * length_ );
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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( void )
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{
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}
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void Drone :: clear( void )
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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( StkFloat frequency )
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{
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StkFloat freakency = frequency;
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if ( frequency <= 0.0 ) {
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errorString_ << "Drone::setFrequency: parameter is less than or equal to zero!";
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handleError( StkError::WARNING );
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freakency = 220.0;
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}
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// Delay = length - approximate filter delay.
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StkFloat delay = (Stk::sampleRate() / freakency) - 0.5;
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if ( delay <= 0.0 )
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delay = 0.3;
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else if (delay > length_)
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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_ = 0.99999;
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}
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void Drone :: pluck( StkFloat amplitude )
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{
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envelope_.keyOn();
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}
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void Drone :: noteOn( StkFloat frequency, StkFloat 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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errorString_ << "Drone::NoteOn: frequency = " << frequency << ", amplitude = " << amplitude << ".";
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handleError( StkError::DEBUG_WARNING );
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#endif
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}
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void Drone :: noteOff( StkFloat amplitude )
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{
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loopGain_ = 1.0 - amplitude;
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if ( loopGain_ < 0.0 ) {
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errorString_ << "Drone::noteOff: amplitude is greater than 1.0 ... setting to 1.0!";
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handleError( StkError::WARNING );
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loopGain_ = 0.0;
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}
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else if ( loopGain_ > 1.0 ) {
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errorString_ << "Drone::noteOff: amplitude is < 0.0 ... setting to 0.0!";
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handleError( StkError::WARNING );
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loopGain_ = 0.99999;
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}
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#if defined(_STK_DEBUG_)
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errorString_ << "Drone::noteOff: amplitude = " << amplitude << ".";
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handleError( StkError::DEBUG_WARNING );
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#endif
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}
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} // stk namespace
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