<!DOCTYPE html>
<html>
<head>
<meta charset='utf-8' />
<title>Animate 3D buildings based on ambient sounds</title>
<meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
<script src='https://api.tiles.mapbox.com/mapbox-gl-js/v0.53.1/mapbox-gl.js'></script>
<link href='https://api.tiles.mapbox.com/mapbox-gl-js/v0.53.1/mapbox-gl.css' rel='stylesheet' />
<style>
body { margin:0; padding:0; }
#map { position:absolute; top:0; bottom:0; width:100%; }
</style>
</head>
<body>
 
<div id='map'></div>
 
<script>
mapboxgl.accessToken = '<your access token here>';
/* global Promise */
 
// Use a minimal variant of the Mapbox Dark style, with certain features removed.
var map = new mapboxgl.Map({
style: 'mapbox://styles/examples/cj68bstx01a3r2rndlud0pwpv',
center: {
lng: -74.00649562332922,
lat: 40.70811328605049
},
zoom: 15,
pitch: 55,
container: 'map'
});
 
map.addControl(new mapboxgl.FullscreenControl());
 
map.on('load', function() {
var bins = 16;
var maxHeight = 200;
var binWidth = maxHeight / bins;
 
// Divide the buildings into 16 bins based on their true height, using a layer filter.
for (var i = 0; i < bins; i++) {
map.addLayer({
'id': '3d-buildings-' + i,
'source': 'composite',
'source-layer': 'building',
'filter': ['all', ['==', 'extrude', 'true'], ['>', 'height', i * binWidth], ['<=', 'height', (i + 1) * binWidth]],
'type': 'fill-extrusion',
'minzoom': 15,
'paint': {
'fill-extrusion-color': '#aaa',
'fill-extrusion-height-transition': {
duration: 0,
delay: 0
},
'fill-extrusion-opacity': .6
}
});
}
 
// Older browsers might not implement mediaDevices at all, so we set an empty object first
if (navigator.mediaDevices === undefined) {
navigator.mediaDevices = {};
}
 
// Some browsers partially implement mediaDevices. We can't just assign an object
// with getUserMedia as it would overwrite existing properties.
// Here, we will just add the getUserMedia property if it's missing.
if (navigator.mediaDevices.getUserMedia === undefined) {
navigator.mediaDevices.getUserMedia = function (constraints) {
 
// First get ahold of the legacy getUserMedia, if present
var getUserMedia = navigator.webkitGetUserMedia || navigator.mozGetUserMedia;
 
// Some browsers just don't implement it - return a rejected promise with an error
// to keep a consistent interface
if (!getUserMedia) {
return Promise.reject(new Error('getUserMedia is not implemented in this browser'));
}
 
// Otherwise, wrap the call to the old navigator.getUserMedia with a Promise
return new Promise(function (resolve, reject) {
getUserMedia.call(navigator, constraints, resolve, reject);
});
};
}
 
navigator.mediaDevices.getUserMedia({audio: true})
.then(function (stream) {
// Set up a Web Audio AudioContext and AnalyzerNode, configured to return the
// same number of bins of audio frequency data.
var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
 
var analyser = audioCtx.createAnalyser();
analyser.minDecibels = -90;
analyser.maxDecibels = -10;
analyser.smoothingTimeConstant = 0.85;
 
var source = audioCtx.createMediaStreamSource(stream);
source.connect(analyser);
 
analyser.fftSize = bins * 2;
 
var dataArray = new Uint8Array(bins);
 
function draw(now) {
analyser.getByteFrequencyData(dataArray);
 
// Use that data to drive updates to the fill-extrusion-height property.
var avg = 0;
for (var i = 0; i < bins; i++) {
avg += dataArray[i];
map.setPaintProperty('3d-buildings-' + i, 'fill-extrusion-height', 10 + 4 * i + dataArray[i]);
}
avg /= bins;
 
// Animate the map bearing and light color over time, and make the light more
// intense when the audio is louder.
map.setBearing(now / 500);
map.setLight({
color: "hsl(" + now / 100 % 360 + "," + Math.min(50 + avg / 4, 100) + "%,50%)",
intensity: Math.min(1, avg / 256 * 10)
});
 
requestAnimationFrame(draw);
}
 
requestAnimationFrame(draw);
})
.catch(function (err) {
console.log('The following gUM error occured: ' + err);
});
});
</script>
 
</body>
</html>