Animate a point | UNL Map JS Docs

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

Note

If you want to test this example, edit it in JSFiddle or CodePen and replace the "YOUR-OWN-API-KEY" and "YOUR-OWN-VPM-ID" placeholders with your actual api key and vpm id.

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Animate a point</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no" />
<script src="https://unpkg.com/unl-map-js@0.1.5/lib/unl-map-js.js"></script>
<link href="https://unpkg.com/unl-map-js@0.1.5/lib/unl-map-js.css" rel="stylesheet" />
<link
href="https://unpkg.com/maplibre-gl@2.1.9/dist/maplibre-gl.css"
rel="stylesheet"
/>
<style>
	body { margin: 0; padding: 0; }
	#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<div id="map"></div>
<script>
var map = new UnlSdk.Map({
container: "map",
apiKey: "YOUR-OWN-API-KEY",
vpmId: "YOUR-OWN-VPM-ID",
center: [0, 0],
zoom: 2,
});
 
var radius = 20;
 
function pointOnCircle(angle) {
return {
type: "Point",
coordinates: [Math.cos(angle) * radius, Math.sin(angle) * radius],
};
}
 
map.on("load", function () {
// 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>