sketch_random.js

There are many ways to create song data, in this example makeSongRandom() generates a song by randomly choosing notes from a set.

setup() is called by p5 kick off the program.

function setup() {
	createCanvas(640, 360);

Create an instance of MonoSynth to play the notes.

	var synth = new MonoSynth();

Generate a song.

	var song = makeSongRandom();

Pass the song to the synth.

	synth.playNotes(song);
}

makeSongRandom() generates the song data.

function makeSongRandom() {

Start with an empty array, we can push() notes onto.

	var song = [];

Lets make sixteen notes.

	for (var i = 0; i < 16; i++) {

Create an array holding the scale note values. We will pick values at random from this array.

Here we use the notes in the Chromatic Scale (all the notes in the octave)

		var scale = [60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, "rest"];

Or we could use the notes in C Major

		/* var scale = sample([60, 62, 64, 65, 67, 69, 71, "rest"]); */

Or we could use the notes in C Minor

		/* var scale = sample([60, 62, 63, 65, 67, 68, 70, "rest"]); */

Each note in the song data is an array with two values: note and length. Here, a new note is created by randomly picking a note and length.

		var note = [
			sample(scale),
			sample([1 / 2, 1 / 4, 1 / 4, 1 / 4])
		];

Add the note to the song.

		song.push();
	}

We’ve made a song, send it back to the caller.

	return song;
}

sample() recieves and array, selects an item in the array randomly, and returns it

function sample(a) {
	return a[floor(random(a.length))];
}