Animate a point along a line | Mapbox GL JS

This example animates the position of a point by updating a GeoJSON source on each frame.

It first defines the animation as a GeoJSON object. Then it adds a GeoJSON source referring to that GeoJSON, and adds a circle layer that uses that source.

Finally, it starts the animation with the JavaScript window.requestAnimationFrame() method to continuously update the GeoJSON object, resulting in a moving circle on the map.

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Animate a point along a line</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
<link href="https://api.mapbox.com/mapbox-gl-js/v3.3.0/mapbox-gl.css" rel="stylesheet">
<script src="https://api.mapbox.com/mapbox-gl-js/v3.3.0/mapbox-gl.js"></script>
<style>
body { margin: 0; padding: 0; }
#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<div id="map"></div>
<script>
	// TO MAKE THE MAP APPEAR YOU MUST
	// ADD YOUR ACCESS TOKEN FROM
	// https://account.mapbox.com
	mapboxgl.accessToken = 'YOUR_MAPBOX_ACCESS_TOKEN';
    const map = new mapboxgl.Map({
        container: 'map',
        // Choose from Mapbox's core styles, or make your own style with Mapbox Studio
        style: 'mapbox://styles/mapbox/streets-v12',
        center: [0, 0],
        zoom: 2
    });

    const radius = 20;

    function pointOnCircle(angle) {
        return {
            'type': 'Point',
            'coordinates': [Math.cos(angle) * radius, Math.sin(angle) * radius]
        };
    }

    map.on('load', () => {
        // Add a source and layer displaying a point which will be animated in a circle.
        map.addSource('point', {
            'type': 'geojson',
            'data': pointOnCircle(0)
        });

        map.addLayer({
            'id': 'point',
            'source': 'point',
            'type': 'circle',
            'paint': {
                'circle-radius': 10,
                'circle-color': '#007cbf'
            }
        });

        function animateMarker(timestamp) {
            // Update the data to a new position based on the animation timestamp. The
            // divisor in the expression `timestamp / 1000` controls the animation speed.
            map.getSource('point').setData(pointOnCircle(timestamp / 1000));

            // Request the next frame of the animation.
            requestAnimationFrame(animateMarker);
        }

        // Start the animation.
        animateMarker(0);
    });
</script>

</body>
</html>

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