sketch_brownian.js

sketch_brownian.js
¶

This example builds on sketch_basic.js It creates a song by moving up or down the scale one step at a time.

¶

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

function setup() {
	createCanvas(640, 360);
	var synth = new MonoSynth();

¶

Create the song and pass it to the synth.
```
	synth.playNotes(makeSongBrownian());
}
```
¶

makeSongBasic() generates the song data.
```
function makeSongBrownian() {
```
¶

Start with an empty array, we can push() notes onto
```
	var song = [];
```
¶

Create an array holding the scale note values. 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"]); */

¶

First pick a random position in the scale

	var index = floor(random(scale.length));

¶

Let’s make sixteen notes.
```
	for (var i = 0; i < 16; i++) {
```
¶

Choose a step size from a list, and step index up/down that amount. Here our possible steps are small.
```
		index = index + sample([-1, 0, 1]);
```

¶

Or we could use bigger and smaller steps.

		/* index = index + sample([-2, -1, 1, 2]); */

¶

We don’t want to walk outside the bounds of our array. Use constrain to make sure.
```
		index = constrain(index, 0, scale.length - 1);
```

¶

Create new note, and push it onto the song.

		song.push([
			scale[index],
			sample([1 / 2, 1 / 4, 1 / 4, 1 / 4])
		]);
	}

¶

Send our complete song 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))];
}
```