From 37d5458322ccf9d1b0be825cbbd0d7e2d7e2bf6a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=BCrg=20Lehni?= <juerg@scratchdisk.com>
Date: Wed, 11 Dec 2013 02:15:51 +0100
Subject: [PATCH] Include Satie Sound Analysis Example.

---
 examples/Paperjs.org/SatieLikedToDraw.html | 141 +++++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 examples/Paperjs.org/SatieLikedToDraw.html
diff --git a/examples/Paperjs.org/SatieLikedToDraw.html b/examples/Paperjs.org/SatieLikedToDraw.html
new file mode 100644
index 00000000..9d9c1f2f
--- /dev/null
+++ b/examples/Paperjs.org/SatieLikedToDraw.html
@@ -0,0 +1,141 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="UTF-8">
+<title>Erik Liked To Dance</title>
+<link rel="stylesheet" href="../css/style.css">
+<script type="text/javascript" src="../../dist/paper.js"></script>
+<script type="text/paperscript" canvas="canvas">
+	var leftPath = new Path({
+	    strokeColor: 'red',
+		opacity: 0.5
+	});
+
+	var rightPath = new Path({
+		strokeColor: 'green',
+		opacity: 0.5
+	});
+
+	var amount = 8;
+	var step = view.size.width / (amount + 1);
+	var scale = view.size.height / 1.5;
+	var flip = false;
+
+	for (var i = 0; i <= amount; i++) {
+		leftPath.add(new Point(i * step, 0));
+		rightPath.add(new Point(i * step, 0));
+	}
+
+	var group = new Group({
+		children: [leftPath, rightPath],
+		transformContent: false,
+		strokeWidth: 30,
+		strokeJoin: 'round',
+		strokeCap: 'butt',
+		registration: leftPath.position,
+		position: view.center
+	});
+
+	function onMouseDown() {
+		flip = !flip;
+	}
+
+	function onKeyDown(event) {
+		if (event.key === 'space') {
+			group.fullySelected = !group.fullySelected;
+		}
+	}
+
+	var audio, source, analyserL, analyserR, freqByteData;
+
+	view.onFrame = function() {
+		var step = view.size.width / (amount + 1);
+		analyserL.getByteFrequencyData(freqByteData);
+		var leftBands = getEqualizerBands(freqByteData, true);
+		analyserR.getByteFrequencyData(freqByteData);
+		var rightBands = getEqualizerBands(freqByteData, true);
+		for (var i = 1; i <= amount; i++) {
+			leftPath.segments[i].point = [i * step, -leftBands[i - 1] * scale];
+			rightPath.segments[i].point = [i * step, -rightBands[i - 1] * scale * (flip ? -1 : 1)];
+		}
+		leftPath.smooth();
+		rightPath.smooth();
+		group.registration = [leftPath.position.x, 0];
+		group.position = view.center;
+	}
+
+	// Pause animation until we have data
+	view.pause();
+
+	var AudioContext = window.AudioContext || window.webkitAudioContext;
+	if (AudioContext) {
+		audio = new AudioContext();
+		source = audio.createBufferSource();
+		// Create two separate analyzers for left and right channel.
+		analyserL = audio.createAnalyser();
+		analyserL.smoothingTimeConstant = 0.25;
+		analyserL.fftSize = Math.pow(2, amount) * 2;
+		analyserR = audio.createAnalyser();
+		analyserR.smoothingTimeConstant = analyserL.smoothingTimeConstant;
+		analyserR.fftSize = analyserL.fftSize;
+		// Create the buffer to receive the analyzed data.
+		freqByteData = new Uint8Array(analyserL.frequencyBinCount);
+		// Create a splitter to feed them both
+		var splitter = audio.createChannelSplitter();
+		// Connect audio processing graph
+		source.connect(splitter);
+		splitter.connect(analyserL, 0, 0);
+		splitter.connect(analyserR, 1, 0);
+		// Connect source to output also so we can hear it
+		source.connect(audio.destination);
+		loadAudioBuffer('http://dl.dropboxusercontent.com/s/ozlvjokqu7ujjwh/gnossienne.mp3');
+	} else {
+		// TODO: Print error message
+		alert('Audio not supported');
+	}
+
+	function loadAudioBuffer(url) {
+		// Load asynchronously
+		var request = new XMLHttpRequest();
+		request.open("GET", url, true);
+		request.responseType = "arraybuffer";
+
+		request.onload = function() { 
+			audio.decodeAudioData(
+				request.response,
+				function(buffer) {
+					source.buffer = buffer;
+					source.loop = true;
+					source.start(0);
+					view.play();
+				},
+				
+				function(buffer) {
+					alert("Error loading MP3");
+				}
+			);
+		};
+		request.send();
+	}
+
+	function getEqualizerBands(data) {
+		var bands = [];
+		var amount = Math.sqrt(data.length) / 2;
+		for(var i = 0; i < amount; i++) {
+			var start = Math.pow(2, i) - 1;
+			var end = start * 2 + 1;
+			var sum = 0;
+			for (var j = start; j < end; j++) {
+				sum += data[j];
+			}
+			var avg = sum / (255 * (end - start));
+			bands[i] = Math.sqrt(avg / Math.sqrt(2));
+		}
+		return bands;
+	}
+	</script>
+</head>
+<body>
+	<canvas id="canvas" resize></canvas>
+</body>
+</html>
\ No newline at end of file
