let osc, envelope;

​

let notes = [];

// the amount of notes

let noteAmount = 8;

// the periods of the wave in the notes

let periods = 3.57;

// the highest and lowest midi note

let upper = 72;

let lower = 48;

// counter for note selection

let count = 0;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  // The sinewave note array generator

  for (var i=0; i<noteAmount; i++){

    // get the amplitude value of a sinewave function based on 

    // index in note array and multiplied by periods

    let a = Math.sin(i/noteAmount*Math.PI*periods);

    // translate the amplitude -1/1 range to a note within 

    // upper/lower limits, floor to get an integer for MIDI

    notes[i] = Math.floor((a * 0.5 + 0.5) * (upper-lower) + lower);

  }

  console.log('notes:', notes);

  // setup a synth

  osc = new p5.SinOsc();

  envelope = new p5.Envelope();

  envelope.setADSR(0.001, 0.2, 0, 0);

  envelope.setRange(1, 0);

}

​

function draw() {

  background(0);

​

  // play a note every n-frames

  if (frameCount % 12 === 0) {

    // get the value from the note array and convert to frequency

    let frequency = midiToFreq(notes[count]);

    osc.freq(frequency);

    osc.start();

​

    envelope.play(osc, 0, 0.1);

    // increment counter within note array length

    count = (count + 1) % notes.length;

  }

}

​