> For the complete documentation index, see [llms.txt](https://docs.mapbox.com/mapbox-gl-js/ja/llms.txt)
# Animate 3D buildings based on ambient sounds
This example uses [runtime styling](https://docs.mapbox.com/help/glossary/runtime-styling/) with the [Web Audio API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Audio_API) to create a map where the 3D buildings dynamically change height to the rhythm of your ambient environment, giving the appearance of dancing.
It uses [`getUserMedia`](https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getUserMedia) to access audio from the user's environment, then analyzes that sound for loudness and uses the loudness levels to adjust the [`fill-extrusion-height`](https://docs.mapbox.com/style-spec/reference/layers/?size=n_10_n#paint-fill-extrusion-fill-extrusion-height) property of the [`fill-extrusion` layer](https://docs.mapbox.com/style-spec/reference/layers/#fill-extrusion).
To optimize performance, it uses the [`==`](https://docs.mapbox.com/style-spec/reference/expressions/#==), [`>`](https://docs.mapbox.com/style-spec/reference/expressions/#%3E) and [`<=`](https://docs.mapbox.com/style-spec/reference/expressions/#%3C=) expression operators to filter buildings in the layer based on their height data.
> Example code:
**JavaScript**
```html
Animate 3D buildings based on ambient sounds
```
**React**
```jsx
import React, { useEffect, useRef } from 'react';
import * as mapboxgl from 'mapbox-gl/esm';
import 'mapbox-gl/dist/mapbox-gl.css';
const MapboxExample = () => {
const mapContainerRef = useRef();
const mapRef = useRef();
useEffect(() => {
mapRef.current = new mapboxgl.Map({
// TO MAKE THE MAP APPEAR YOU MUST
// ADD YOUR ACCESS TOKEN FROM
// https://account.mapbox.com
accessToken: 'YOUR_MAPBOX_ACCESS_TOKEN',
style: 'mapbox://styles/examples/cj68bstx01a3r2rndlud0pwpv',
center: {
lng: -74.0064,
lat: 40.7081
},
zoom: 15,
pitch: 55,
container: mapContainerRef.current,
antialias: true
});
mapRef.current.addControl(new mapboxgl.FullscreenControl());
mapRef.current.on('load', () => {
const bins = 16;
const maxHeight = 200;
const binWidth = maxHeight / bins;
// Divide the buildings into 16 bins based on their true height, using a layer filter.
for (let i = 0; i < bins; i++) {
mapRef.current.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': 0.6
}
});
}
// 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 = (constraints) => {
// First get ahold of the legacy getUserMedia, if present
const 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((resolve, reject) => {
getUserMedia.call(navigator, constraints, resolve, reject);
});
};
}
navigator.mediaDevices
.getUserMedia({ audio: true })
.then((stream) => {
// Set up a Web Audio AudioContext and AnalyzerNode, configured to return the
// same number of bins of audio frequency data.
const audioCtx = new (window.AudioContext ||
window.webkitAudioContext)();
const analyser = audioCtx.createAnalyser();
analyser.minDecibels = -90;
analyser.maxDecibels = -10;
analyser.smoothingTimeConstant = 0.85;
const source = audioCtx.createMediaStreamSource(stream);
source.connect(analyser);
analyser.fftSize = bins * 2;
const dataArray = new Uint8Array(bins);
function draw(now) {
analyser.getByteFrequencyData(dataArray);
// Use that data to drive updates to the fill-extrusion-height property.
let avg = 0;
for (let i = 0; i < bins; i++) {
avg += dataArray[i];
mapRef.current.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.
mapRef.current.setBearing(now / 500);
const hue = (now / 100) % 360;
const saturation = Math.min(50 + avg / 4, 100);
mapRef.current.setLight({
color: `hsl(${hue},${saturation}%,50%)`,
intensity: Math.min(1, (avg / 256) * 10)
});
requestAnimationFrame(draw);
}
requestAnimationFrame(draw);
})
.catch((err) => {
console.log('The following gUM error occurred:', err);
});
});
return () => {
mapRef.current.remove();
};
}, []);
return ;
};
export default MapboxExample;
```