mirror of
https://github.com/thestk/stk
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118 lines
3.2 KiB
C++
118 lines
3.2 KiB
C++
#ifndef STK_DRONE_H
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#define STK_DRONE_H
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#include "Instrmnt.h"
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#include "DelayA.h"
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#include "OneZero.h"
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#include "ADSR.h"
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#include "Noise.h"
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namespace stk {
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/***************************************************/
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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--2023.
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*/
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/***************************************************/
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class Drone : public Instrmnt
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{
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public:
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//! Class constructor, taking the lowest desired playing frequency.
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Drone( StkFloat lowestFrequency = 20 );
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//! Class destructor.
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~Drone( void );
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//! Reset and clear all internal state.
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void clear( void );
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//! Set instrument parameters for a particular frequency.
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void setFrequency( StkFloat frequency );
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//! Pluck the string with the given amplitude using the current frequency.
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void pluck( StkFloat amplitude );
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//! Start a note with the given frequency and amplitude.
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void noteOn( StkFloat frequency, StkFloat amplitude );
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//! Stop a note with the given amplitude (speed of decay).
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void noteOff( StkFloat amplitude );
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//! Compute and return one output sample.
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StkFloat tick( unsigned int channel = 0 );
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//! Fill a channel of the StkFrames object with computed outputs.
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/*!
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The \c channel argument must be less than the number of
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channels in the StkFrames argument (the first channel is specified
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by 0). However, range checking is only performed if _STK_DEBUG_
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is defined during compilation, in which case an out-of-range value
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will trigger an StkError exception.
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*/
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StkFrames& tick( StkFrames& frames, unsigned int channel = 0 );
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protected:
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DelayA delayLine_;
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OneZero loopFilter_;
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ADSR envelope_;
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Noise noise_;
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StkFloat loopGain_;
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unsigned long length_;
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};
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inline StkFloat Drone :: tick( unsigned int )
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{
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// Here's the whole inner loop of the instrument!!
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lastFrame_[0] = delayLine_.tick( loopFilter_.tick( delayLine_.lastOut() * loopGain_ )
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+ ( 0.005 * envelope_.tick() * noise_.tick() ) );
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return lastFrame_[0];
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}
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inline StkFrames& Drone :: tick( StkFrames& frames, unsigned int channel )
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{
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unsigned int nChannels = lastFrame_.channels();
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#if defined(_STK_DEBUG_)
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if ( channel > frames.channels() - nChannels ) {
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oStream_ << "Drone::tick(): channel and StkFrames arguments are incompatible!";
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handleError( StkError::FUNCTION_ARGUMENT );
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}
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#endif
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StkFloat *samples = &frames[channel];
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unsigned int j, hop = frames.channels() - nChannels;
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if ( nChannels == 1 ) {
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for ( unsigned int i=0; i<frames.frames(); i++, samples += hop )
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*samples++ = tick();
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}
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else {
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for ( unsigned int i=0; i<frames.frames(); i++, samples += hop ) {
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*samples++ = tick();
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for ( j=1; j<nChannels; j++ )
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*samples++ = lastFrame_[j];
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}
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}
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return frames;
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}
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} // stk namespace
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#endif
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