Demonstrates how to animate features.
This example shows how to use postrender and vectorContext to animate features. Here we choose to do a flash animation each time a feature is added to the layer.
import 'ol/ol.css';
import Feature from 'ol/Feature';
import Map from 'ol/Map';
import Point from 'ol/geom/Point';
import View from 'ol/View';
import {Circle as CircleStyle, Stroke, Style} from 'ol/style';
import {OSM, Vector as VectorSource} from 'ol/source';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer';
import {easeOut} from 'ol/easing';
import {fromLonLat} from 'ol/proj';
import {getVectorContext} from 'ol/render';
import {unByKey} from 'ol/Observable';
var tileLayer = new TileLayer({
source: new OSM({
wrapX: false,
}),
});
var map = new Map({
layers: [tileLayer],
target: 'map',
view: new View({
center: [0, 0],
zoom: 1,
multiWorld: true,
}),
});
var source = new VectorSource({
wrapX: false,
});
var vector = new VectorLayer({
source: source,
});
map.addLayer(vector);
function addRandomFeature() {
var x = Math.random() * 360 - 180;
var y = Math.random() * 180 - 90;
var geom = new Point(fromLonLat([x, y]));
var feature = new Feature(geom);
source.addFeature(feature);
}
var duration = 3000;
function flash(feature) {
var start = new Date().getTime();
var listenerKey = tileLayer.on('postrender', animate);
function animate(event) {
var vectorContext = getVectorContext(event);
var frameState = event.frameState;
var flashGeom = feature.getGeometry().clone();
var elapsed = frameState.time - start;
var elapsedRatio = elapsed / duration;
// radius will be 5 at start and 30 at end.
var radius = easeOut(elapsedRatio) * 25 + 5;
var opacity = easeOut(1 - elapsedRatio);
var style = new Style({
image: new CircleStyle({
radius: radius,
stroke: new Stroke({
color: 'rgba(255, 0, 0, ' + opacity + ')',
width: 0.25 + opacity,
}),
}),
});
vectorContext.setStyle(style);
vectorContext.drawGeometry(flashGeom);
if (elapsed > duration) {
unByKey(listenerKey);
return;
}
// tell OpenLayers to continue postrender animation
map.render();
}
}
source.on('addfeature', function (e) {
flash(e.feature);
});
window.setInterval(addRandomFeature, 1000);
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Custom Animation</title>
<!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
<script src="https://unpkg.com/elm-pep"></script>
<style>
.map {
width: 100%;
height:400px;
}
</style>
</head>
<body>
<div id="map" class="map"></div>
<script src="main.js"></script>
</body>
</html>
{
"name": "feature-animation",
"dependencies": {
"ol": "6.5.0"
},
"devDependencies": {
"parcel": "^2.0.0-beta.1"
},
"scripts": {
"start": "parcel index.html",
"build": "parcel build --public-url . index.html"
}
}