class Synth implements ddf.minim.ugens.Instrument {
  Oscil       wave;
  Damp        env;
  int         noteNumber;
  Blip        blip;
  
  Synth( int note, int velocity ) {
    noteNumber = note;
    float freq = Frequency.ofMidiNote( noteNumber ).asHz();
    float amp  = (float)(velocity-1) / 126.0f;
    
    wave = new Oscil( freq, amp, Waves.SQUARE );
    env  = new Damp( 0.001f, 0.1f, 1.0f );
    
    wave.patch( env );
  }
  
  void noteOn( float dur ) {
    // make visual
    color c = color( 0, 200, 64, 255*(wave.amplitude.getLastValue()) );
    blip = new Blip( c, map(noteNumber, 30, 55, height, 0), 200 );
    blips.add( blip );
    
    // make sound
    env.activate();
    env.patch( out );
  }
  
  void noteOff() {
    env.unpatchAfterDamp( out );
    blips.remove( blip );
  }
}