Animate a line

Animate a line by updating a GeoJSON source on each frame. See the example: https://docs.mapbox.com//mapbox-gl-js/example/animate-a-line/

by Amatewasu

HTML

<script src="https://api.mapbox.com/mapbox-gl-js/v2.1.1/mapbox-gl.js"></script>
<link rel="stylesheet" href="https://api.mapbox.com/mapbox-gl-js/v2.1.1/mapbox-gl.css">


<div id="map"></div>
<button id="pause"></button>

CSS

body { margin: 0; padding: 0; }
#map { position: absolute; top: 0; bottom: 0; width: 100%; }

    button {
        position: absolute;
        margin: 20px;
    }

    #pause::after {
        content: 'Pause';
    }

    #pause.pause::after {
        content: 'Play';
    }

JavaScript

mapboxgl.accessToken = 'pk.eyJ1IjoiYW1hdGV3YXN1IiwiYSI6ImNrYXV2ZTlqYTB6YjQyeWwyYXZvZTZ3cWYifQ.WCLjyDZ7Bn9bLM1E2BzQcw';
    var map = new mapboxgl.Map({
        container: 'map',
        style: 'mapbox://styles/mapbox/streets-v11',
        center: [0, 0],
        zoom: 0.5
    });

    // Create a GeoJSON source with an empty lineString.
    var geojson = {
        'type': 'FeatureCollection',
        'features': [
            {
                'type': 'Feature',
                'geometry': {
                    'type': 'LineString',
                    'coordinates': [[0, 0]]
                }
            }
        ]
    };

    var speedFactor = 30; // number of frames per longitude degree
    var animation; // to store and cancel the animation
    var startTime = 0;
    var progress = 0; // progress = timestamp - startTime
    var resetTime = false; // indicator of whether time reset is needed for the animation
    var pauseButton = document.getElementById('pause');

    map.on('load', function () {
        map.addSource('line', {
            'type': 'geojson',
            'data': geojson
        });

        // add the line which will be modified in the animation
        map.addLayer({
            'id': 'line-animation',
            'type': 'line',
            'source': 'line',
            'layout': {
                'line-cap': 'round',
                'line-join': 'round'
            },
            'paint': {
                'line-color': '#ed6498',
                'line-width': 5,
                'line-opacity': 0.8
            }
        });

        startTime = performance.now();

        animateLine();

        // click the button to pause or play
        pauseButton.addEventListener('click', function () {
            pauseButton.classList.toggle('pause');
            if (pauseButton.classList.contains('pause')) {
                cancelAnimationFrame(animation);
            } else {
                resetTime = true;
                animateLine();
        ...