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Animate a point

Animate the position of a point by updating a GeoJSON source on each frame.

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Animate a point</title>
    <meta property="og:description" content="Animate the position of a point by updating a GeoJSON source on each frame." />
    <meta charset='utf-8'>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel='stylesheet' href='https://unpkg.com/[email protected]/dist/maplibre-gl.css' />
    <script src='https://unpkg.com/[email protected]/dist/maplibre-gl.js'></script>
    <style>
        body { margin: 0; padding: 0; }
        html, body, #map { height: 100%; }
    </style>
</head>
<body>
<div id="map"></div>
<script>
    const map = new maplibregl.Map({
        container: 'map',
        style:
            'https://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL',
        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>