Merge pull request #3 from skratchdot/gh-pages

adding links and publishing demo

demo.html

@@ -0,0 +1 @@
+<script src=litsynth.js></script>

index.html

@@ -34,7 +34,12 @@ <h1 id="litsynth">litsynth</h1>
               <div class="pilwrap ">
                 <a class="pilcrow" href="#section-2">&#182;</a>
               </div>
-              <h2 id="introduction-and-scope">Introduction and scope</h2>
+              <ul>
+<li><a href="https://github.com/padenot/litsynth">Source Code</a></li>
+<li><a href="http://padenot.github.io/litsynth/index.html">Documentation</a></li>
+<li><a href="http://padenot.github.io/litsynth/demo.html">Demonstration</a></li>
+</ul>
+<h2 id="introduction-and-scope">Introduction and scope</h2>
 
             </div>
 

litsynth.js

@@ -0,0 +1,164 @@
+function note2freq(note) {
+  return Math.pow(2, (note - 69) / 12) * 440;
+}
+function S(ac, clap, track) {
+   this.ac = ac;
+   this.clap = clap;
+   this.track = track;
+   this.rev = ac.createConvolver();
+   this.rev.buffer = this.ReverbBuffer();
+   this.sink = ac.createGain();
+   this.sink.connect(this.rev);
+   this.rev.connect(ac.destination);
+   this.sink.connect(ac.destination);
+}
+S.prototype.NoiseBuffer = function() {
+  if (!S._NoiseBuffer) {
+    S._NoiseBuffer = this.ac.createBuffer(1, this.ac.sampleRate / 10, this.ac.sampleRate);
+    var cd = S._NoiseBuffer.getChannelData(0);
+    for (var i = 0; i < cd.length; i++) {
+      cd[i] = Math.random() * 2 - 1;
+    }
+  }
+  return S._NoiseBuffer;
+}
+S.prototype.ReverbBuffer = function() {
+  var len = 0.5 * this.ac.sampleRate,
+      decay = 0.5;
+  var buf = this.ac.createBuffer(2, len, this.ac.sampleRate);
+  for (var c = 0; c < 2; c++) {
+    var channelData = buf.getChannelData(c);
+    for (var i = 0; i < channelData.length; i++) {
+       channelData[i] = (Math.random() * 2 - 1) * Math.pow(1 - i / len, decay);
+    }
+  }
+  return buf;
+}
+S.prototype.Kick = function(t) {
+  var o = this.ac.createOscillator();
+  var g = this.ac.createGain();
+  o.connect(g);
+  g.connect(this.sink);
+  g.gain.setValueAtTime(1.0, t);
+  g.gain.setTargetAtTime(0.0, t, 0.1);
+  o.frequency.value = 100;
+  o.frequency.setTargetAtTime(30, t, 0.15);
+  o.start(t);
+  o.stop(t + 1);
+  var osc2 = this.ac.createOscillator();
+  var gain2 = this.ac.createGain();
+  osc2.frequency.value = 40;
+  osc2.type = "square";
+  osc2.connect(gain2);
+  gain2.connect(this.sink);
+  gain2.gain.setValueAtTime(0.5, t);
+  gain2.gain.setTargetAtTime(0.0, t, 0.01);
+  osc2.start(t);
+  osc2.stop(t + 1);
+}
+S.prototype.Hats = function(t) {
+  var s = this.ac.createBufferSource();
+  s.buffer = this.NoiseBuffer();
+  var g = this.ac.createGain();
+  var hpf = this.ac.createBiquadFilter();
+  hpf.type = "highpass";
+  hpf.frequency.value = 5000;
+  g.gain.setValueAtTime(1.0, t);
+  g.gain.setTargetAtTime(0.0, t, 0.02);
+  s.connect(g);
+  g.connect(hpf);
+  hpf.connect(this.sink);
+  s.start(t);
+}
+S.prototype.Clap = function(t) {
+  var s = this.ac.createBufferSource();
+  var g = this.ac.createGain();
+  s.buffer = this.clap;
+  s.connect(g);
+  g.connect(this.sink);
+  g.gain.value = 0.5;
+  s.start(t);
+}
+S.prototype.Bass = function(t, note) {
+  var o = this.ac.createOscillator();
+  var o2 = this.ac.createOscillator();
+  var g = this.ac.createGain();
+  var g2 = this.ac.createGain();
+  o.frequency.value = o2.frequency.value = note2freq(note);
+  o.type = o2.type = "sawtooth";
+  g.gain.setValueAtTime(1.0, t);
+  g.gain.setTargetAtTime(0.0, t, 0.1);
+  g2.gain.value = 0.5;
+  var lp = this.ac.createBiquadFilter();
+  lp.Q.value = 25;
+  lp.frequency.setValueAtTime(300, t);
+  lp.frequency.setTargetAtTime(3000, t, 0.05);
+  o.connect(g);
+  o2.connect(g);
+  g.connect(lp);
+  lp.connect(g2);
+  g2.connect(this.sink);
+  o.start(t);
+  o.stop(t + 1);
+}
+S.prototype.clock = function() {
+  var beatLen = 60 / this.track.tempo;
+  return (this.ac.currentTime  - this.startTime) / beatLen;
+}
+S.prototype.start = function() {
+  this.startTime = this.ac.currentTime;
+  this.nextScheduling = 0;
+  this.scheduler();
+}
+S.prototype.scheduler = function() {
+  var beatLen = 60 / this.track.tempo;
+  var current = this.clock();
+  var lookahead = 0.5;
+  if (current + lookahead > this.nextScheduling) {
+    var steps = [];
+    for (var i = 0; i < 4; i++) {
+      steps.push(this.nextScheduling + i * beatLen / 4);
+    }
+    for (var i in this.track.tracks) {
+      for (var j = 0; j < steps.length; j++) {
+        var idx = Math.round(steps[j] / ((beatLen / 4)));
+        var note = this.track.tracks[i][idx % this.track.tracks[i].length];
+        if (note != 0) {
+          this[i](steps[j], note);
+        }
+      }
+    }
+    this.nextScheduling += (60 / this.track.tempo);
+  }
+  setTimeout(this.scheduler.bind(this), 100);
+}
+var track = {
+  tempo: 135,
+  tracks: {
+    Kick: [ 1, 0, 0, 0, 1, 0, 0, 0,
+            1, 0, 0, 0, 1, 0, 0, 0,
+            1, 0, 0, 0, 1, 0, 0, 0,
+            1, 0, 0, 0, 1, 0, 0, 0],
+    Hats: [ 0, 0, 1, 0, 0, 0, 1, 0,
+            0, 0, 1, 0, 0, 0, 1, 1,
+            0, 0, 1, 0, 0, 0, 1, 0,
+            0, 0, 1, 0, 0, 0, 1, 0 ],
+    Clap: [ 0, 0, 0, 0, 1, 0, 0, 0,
+            0, 0, 0, 0, 1, 0, 0, 0,
+            0, 0, 0, 0, 1, 0, 0, 0,
+            0, 0, 0, 0, 1, 0, 0, 0],
+    Bass: [36, 0,38,36,36,38,41, 0,
+           36,60,36, 0,39, 0,48, 0,
+           36, 0,24,60,40,40,24,24,
+           36,60,36, 0,39, 0,48, 0 ]
+  }
+};
+fetch('clap.ogg').then((response) => {
+  response.arrayBuffer().then((arraybuffer) => {
+    var ac = new AudioContext();
+    ac.decodeAudioData(arraybuffer).then((clap) => {
+      var s = new S(ac, clap, track);
+      s.start();
+    });
+  });
+});