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Animate a point along a route

Additional Developer Resources

Use Turf to smoothly animate a point along the distance of a line.

Referencing images in a style's sprite

This example uses the Mapbox Streets style. The icon-image used in this example comes from the Mapbox Streets style's sprite.

To view all available images in a style's sprite or add additional images, open the style in Mapbox Studio and click the Images tab. To add a new image to the style at runtime see the Add an icon to the map example.

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Animate a point along a route</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
<link href="https://api.mapbox.com/mapbox-gl-js/v3.9.0/mapbox-gl.css" rel="stylesheet">
<script src="https://api.mapbox.com/mapbox-gl-js/v3.9.0/mapbox-gl.js"></script>
<style>
body { margin: 0; padding: 0; }
#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<style>
    .overlay {
        position: absolute;
        top: 10px;
        left: 10px;
    }

    .overlay button {
        font:
            600 12px/20px 'Helvetica Neue',
            Arial,
            Helvetica,
            sans-serif;
        background-color: #3386c0;
        color: #fff;
        display: inline-block;
        margin: 0;
        padding: 10px 20px;
        border: none;
        cursor: pointer;
        border-radius: 3px;
    }

    .overlay button:hover {
        background-color: #4ea0da;
    }

    .overlay button:disabled {
        background: #f5f5f5;
        color: #c3c3c3;
    }
</style>
<script src="https://unpkg.com/@turf/turf@6/turf.min.js"></script>

<div id="map"></div>
<div class="overlay">
    <button id="replay">Replay</button>
</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/dark-v11',
        center: [-96, 37.8],
        zoom: 3,
        pitch: 40
    });

    // San Francisco
    const origin = [-122.414, 37.776];

    // Washington DC
    const destination = [-77.032, 38.913];

    // A simple line from origin to destination.
    const route = {
        'type': 'FeatureCollection',
        'features': [
            {
                'type': 'Feature',
                'geometry': {
                    'type': 'LineString',
                    'coordinates': [origin, destination]
                }
            }
        ]
    };

    // A single point that animates along the route.
    // Coordinates are initially set to origin.
    const point = {
        'type': 'FeatureCollection',
        'features': [
            {
                'type': 'Feature',
                'properties': {},
                'geometry': {
                    'type': 'Point',
                    'coordinates': origin
                }
            }
        ]
    };

    // Calculate the distance in kilometers between route start/end point.
    const lineDistance = turf.length(route.features[0]);

    const arc = [];

    // Number of steps to use in the arc and animation, more steps means
    // a smoother arc and animation, but too many steps will result in a
    // low frame rate
    const steps = 500;

    // Draw an arc between the `origin` & `destination` of the two points
    for (let i = 0; i < lineDistance; i += lineDistance / steps) {
        const segment = turf.along(route.features[0], i);
        arc.push(segment.geometry.coordinates);
    }

    // Update the route with calculated arc coordinates
    route.features[0].geometry.coordinates = arc;

    // Used to increment the value of the point measurement against the route.
    let counter = 0;

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

        map.addSource('point', {
            'type': 'geojson',
            'data': point
        });

        map.addLayer({
            'id': 'route',
            'source': 'route',
            'type': 'line',
            'paint': {
                'line-width': 2,
                'line-color': '#007cbf'
            }
        });

        map.addLayer({
            'id': 'point',
            'source': 'point',
            'type': 'symbol',
            'layout': {
                // This icon is a part of the Mapbox Streets style.
                // To view all images available in a Mapbox style, open
                // the style in Mapbox Studio and click the "Images" tab.
                // To add a new image to the style at runtime see
                // https://docs.mapbox.com/mapbox-gl-js/example/add-image/
                'icon-image': 'airport',
                'icon-size': 1.5,
                'icon-rotate': ['get', 'bearing'],
                'icon-rotation-alignment': 'map',
                'icon-allow-overlap': true,
                'icon-ignore-placement': true
            }
        });
        let running = false;
        function animate() {
            running = true;
            document.getElementById('replay').disabled = true;
            const start =
                route.features[0].geometry.coordinates[
                    counter >= steps ? counter - 1 : counter
                ];
            const end =
                route.features[0].geometry.coordinates[
                    counter >= steps ? counter : counter + 1
                ];
            if (!start || !end) {
                running = false;
                document.getElementById('replay').disabled = false;
                return;
            }
            // Update point geometry to a new position based on counter denoting
            // the index to access the arc
            point.features[0].geometry.coordinates =
                route.features[0].geometry.coordinates[counter];

            // Calculate the bearing to ensure the icon is rotated to match the route arc
            // The bearing is calculated between the current point and the next point, except
            // at the end of the arc, which uses the previous point and the current point
            point.features[0].properties.bearing = turf.bearing(
                turf.point(start),
                turf.point(end)
            );

            // Update the source with this new data
            map.getSource('point').setData(point);

            // Request the next frame of animation as long as the end has not been reached
            if (counter < steps) {
                requestAnimationFrame(animate);
            }

            counter = counter + 1;
        }

        document.getElementById('replay').addEventListener('click', () => {
            if (running) {
                void 0;
            } else {
                // Set the coordinates of the original point back to origin
                point.features[0].geometry.coordinates = origin;

                // Update the source layer
                map.getSource('point').setData(point);

                // Reset the counter
                counter = 0;

                // Restart the animation
                animate(counter);
            }
        });

        // Start the animation
        animate(counter);
    });
</script>

</body>
</html>
This code snippet will not work as expected until you replace YOUR_MAPBOX_ACCESS_TOKEN with an access token from your Mapbox account.
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