Intro-to-Tone-Part3

Let’s start really controlling musical parameters, using - arrays - random processes - organizing time and preparing for sequences and sampling - chords - for loops #

We will create arrays of pitches and durations to drive a synthesizer.

To create an array in JavaScript, we

JavaScript only uses numbered index.

var nameArray = [];
nameArray[0] = "Danny";
nameArray[1] = "William";
nameArray[2] = "Olivia"

console.log(nameArray.length);

Associative Arrays work to a point, they have an zero length.

var namedArray = [];
namedArray["Bestie"] = "William";
namedArray["Bae"] = "Nick";
namedArray["Jerk"] = "Danny";

console.log(namedArray.length);

Let’s create some arrays!

1. Let’s create an array of note names. (C4, F#5, etc.) – call it noteArray

   var noteArray = [ whatever pitches you want ];

2. And create an array of durations. (.2, .8, 2, etc.) SECONDS – call it durArray

   var durationArray = [ whatever durations you want ];

3. Now let’s create a function that will RANDOMLY select a pitch from the pitch array and a random duration from the durations array.

   function () { var playNote = noteArray[Math.floor(Math.random() * noteArray.length)] }

4. Now to make the synthesizer play the random note at the random duration, we need to re-write the function to play, like we did earlier.

   synth.triggerAttackRelease(playNote, playDur);

Cool, one note. But lets’ play more than one note.

For Loops

Let’s tell javascript to go through our arrays by writing a ‘for loop’

for (i = 0; i < noteArray.length; i++) {
    var playNote = noteArray[Math.floor(Math.random() * noteArray.length)];
    var playDur = durArray[Math.floor(Math.random() * durArray.length)];
    console.log (playNote, playDur);
}

We’ve added a line that tells Console to tell us which notes are being selected.

Let’s look at the console, how fat does everything spit out? We need to do some timing adjustments: we need to use setTimeout function.

setTimeout('function', time);

Let’s wrap our code with the setTimeout function.

There are a few more steps; Let’s make it look right:

function myRandomLoop () {     //  create a loop function
     setTimeout(function () {    //  call a 3s setTimeout when the loop is called
            playNote = noteArray[Math.floor(Math.random()*noteArray.length)];
            playDur = durArray[Math.floor(Math.random()*durArray.length)];
            console.log(playNote, playDur);
            synth.triggerAttackRelease(playNote, playDur);

            i++;                     //  increment the counter
            if (i < 30) {            //  if the counter < 10, call the loop function
                 myLoop();             //  ..  again which will trigger another
            }                        //  ..  setTimeout()
     }, playDur * 1000 + 10)
}