MarkovChain music generation for wavepot

gistfile1.js

var transpose = 24;
var bpm = 240; // Beats per minute
var spb = 60/bpm; // Second per beat


function note(n, octave){
  n += transpose;
  return Math.pow(2, (n - 33 + (12 * (octave || 0))) / 12) * 440;
}

var melodies = [1];
var counter;

//C Major random
var MajorRandom = [
  [1,0,1,0,1,1,0,1,0,1,0,1],
  [0,0,0,0,0,0,0,0,0,0,0,0],
  [1,0,1,0,1,1,0,1,0,1,0,1],
  [0,0,0,0,1,0,0,0,0,0,0,0],
  [1,0,1,0,1,1,0,1,0,1,0,1],
  [1,0,1,0,1,1,0,1,0,1,0,1],
  [0,0,0,0,0,0,0,1,0,0,0,0],
  [1,0,1,0,1,1,0,1,0,1,0,1],
  [0,0,0,0,0,0,0,0,0,1,0,0],
  [1,0,1,0,1,1,0,1,0,1,0,1],
  [0,0,0,0,0,0,0,0,0,0,0,1],
  [1,0,1,0,1,1,0,1,0,1,0,1],
]

//C Major chromatic
var MajorChromatic = [
  [1,0,1,0,0,0,0,0,0,0,0,0],
  [0,0,0,0,0,0,0,0,0,0,0,0],
  [1,0,1,0,1,0,0,0,0,0,0,0],
  [0,0,0,0,1,0,0,0,0,0,0,0],
  [0,0,1,0,1,1,0,0,0,0,0,0],
  [0,0,0,0,1,1,0,1,0,0,0,0],
  [0,0,0,0,0,0,0,0,0,0,0,0],
  [0,0,0,0,0,1,0,1,0,1,0,0],
  [0,0,0,0,0,0,0,0,0,0,0,0],
  [0,0,0,0,0,0,0,1,0,1,0,1],
  [0,0,0,0,0,0,0,0,0,0,0,0],
  [0,0,0,0,0,0,0,0,0,1,0,1],
]

function calcMarkovChain(chain,models,length) {
  function calcNext(table) {
    var current = 0;
    var proba = [];
    for (var i = 0; i < table.length; i++) {
      current+=table[i];
      proba[i] = current;
    }
    var r = Math.random();
    for (i = 0; i < proba.length; i++) {
      proba[i]*= 1/current;
      if (r<proba[i]) {
        return i;
      }
    }
    return 0
  }

  chain.slice(0);
  chain.push(0);
  
  for (var i = 0; i < length; i++) {
    var currentModel = models[chain[i] || 0];
    chain.push(calcNext(currentModel))
  }
  return chain
}


function buildMelodie() {
  var pattern = calcMarkovChain([] ,MajorChromatic,8);
  melodies = [];
  melodies.push.apply(melodies,pattern);
  pattern[(Math.random()*8)|0] += 1;
  pattern[(Math.random()*8)|0] += 1;
  melodies.push.apply(melodies,pattern);
  melodies.push.apply(melodies,melodies.map(function(x){return x+12}));
  return melodies;
}
buildMelodie()

function sin(t,f,a) {
  return a * Math.sin( 2 * Math.PI *  t * f);
}

function sqr(t,f,a) {
  return  ((sin(t,f,a)>0) *2-1) *a;
}

function dsp(t) {
  counter = Math.floor(t/spb); //How many beats have passed
  var noteprogression = (t%spb)/spb
  return sqr(t,note(melodies[counter%melodies.length]),0.1)*sin(t,note(melodies[counter%melodies.length])*2,1)
}