Version 4.0

projects/ragamatic/Drone.cpp

@@ -0,0 +1,102 @@
+/***************************************************/
+/*! \class Drone
+    \brief STK "drone" plucked string model.
+
+    This class implements a simple plucked string
+    physical model based on the Karplus-Strong
+    algorithm.
+
+    This is a digital waveguide model, making its
+    use possibly subject to patents held by
+    Stanford University, Yamaha, and others.
+    There exist at least two patents, assigned to
+    Stanford, bearing the names of Karplus and/or
+    Strong.
+
+    by Perry R. Cook and Gary P. Scavone, 1995 - 2002.
+*/
+/***************************************************/
+
+#include "Drone.h"
+
+Drone :: Drone(MY_FLOAT lowestFrequency)
+{
+  length = (long) (Stk::sampleRate() / lowestFrequency + 1);
+  loopGain = (MY_FLOAT) 0.999;
+  delayLine = new DelayA( (MY_FLOAT)(length / 2.0), length );
+  loopFilter = new OneZero;
+  noise = new Noise;
+  envelope = new ADSR();
+  envelope->setAllTimes(2.0, 0.5, 0.0, 0.5);
+  this->clear();
+}
+
+Drone :: ~Drone()
+{
+  delete delayLine;
+  delete loopFilter;
+  delete envelope;
+  delete noise;
+}
+
+void Drone :: clear()
+{
+  delayLine->clear();
+  loopFilter->clear();
+}
+
+void Drone :: setFrequency(MY_FLOAT frequency)
+{
+  MY_FLOAT freakency = frequency;
+  if ( frequency <= 0.0 ) {
+    cerr << "Drone: setFrequency parameter is less than or equal to zero!" << endl;
+    freakency = 220.0;
+  }
+
+  // Delay = length - approximate filter delay.
+  MY_FLOAT delay = (Stk::sampleRate() / freakency) - (MY_FLOAT) 0.5;
+  if (delay <= 0.0) delay = 0.3;
+  else if (delay > length) delay = length;
+  delayLine->setDelay(delay);
+  loopGain = 0.997 + (freakency * 0.000002);
+  if ( loopGain >= 1.0 ) loopGain = (MY_FLOAT) 0.99999;
+}
+
+void Drone :: pluck(MY_FLOAT amplitude)
+{
+  envelope->keyOn();
+}
+
+void Drone :: noteOn(MY_FLOAT frequency, MY_FLOAT amplitude)
+{
+  this->setFrequency(frequency);
+  this->pluck(amplitude);
+
+#if defined(_STK_DEBUG_)
+  cerr << "Drone: NoteOn frequency = " << frequency << ", amplitude = " << amplitude << endl;
+#endif
+}
+
+void Drone :: noteOff(MY_FLOAT amplitude)
+{
+  loopGain = (MY_FLOAT) 1.0 - amplitude;
+  if ( loopGain < 0.0 ) {
+    cerr << "Drone: noteOff amplitude greater than 1.0!" << endl;
+    loopGain = 0.0;
+  }
+  else if ( loopGain > 1.0 ) {
+    cerr << "Drone: noteOff amplitude less than or zero!" << endl;
+    loopGain = (MY_FLOAT) 0.99999;
+  }
+
+#if defined(_STK_DEBUG_)
+  cerr << "Drone: NoteOff amplitude = " << amplitude << endl;
+#endif
+}
+
+MY_FLOAT Drone :: tick()
+{
+  // Here's the whole inner loop of the instrument!!
+  lastOutput = delayLine->tick( loopFilter->tick( delayLine->lastOut() * loopGain ) + (0.005 * envelope->tick() * noise->tick())); 
+  return lastOutput;
+}