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 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';
const tileLayer = new TileLayer({
source: new OSM({
wrapX: false,
}),
});
const source = new VectorSource({
wrapX: false,
});
const vector = new VectorLayer({
source: source,
});
const map = new Map({
layers: [tileLayer, vector],
target: 'map',
view: new View({
center: [0, 0],
zoom: 1,
multiWorld: true,
}),
});
function addRandomFeature() {
const x = Math.random() * 360 - 180;
const y = Math.random() * 170 - 85;
const geom = new Point(fromLonLat([x, y]));
const feature = new Feature(geom);
source.addFeature(feature);
}
const duration = 3000;
function flash(feature) {
const start = Date.now();
const flashGeom = feature.getGeometry().clone();
const listenerKey = tileLayer.on('postrender', animate);
function animate(event) {
const frameState = event.frameState;
const elapsed = frameState.time - start;
if (elapsed >= duration) {
unByKey(listenerKey);
return;
}
const vectorContext = getVectorContext(event);
const elapsedRatio = elapsed / duration;
// radius will be 5 at start and 30 at end.
const radius = easeOut(elapsedRatio) * 25 + 5;
const opacity = easeOut(1 - elapsedRatio);
const 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);
// 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>
<link rel="stylesheet" href="node_modules/ol/ol.css">
<style>
.map {
width: 100%;
height: 400px;
}
</style>
</head>
<body>
<div id="map" class="map"></div>
<!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
<script src="https://unpkg.com/[email protected]/dist/elm-pep.js"></script>
<script type="module" src="main.js"></script>
</body>
</html>
{
"name": "feature-animation",
"dependencies": {
"ol": "7.0.0"
},
"devDependencies": {
"vite": "^3.0.3",
"@babel/core": "latest"
},
"scripts": {
"start": "vite",
"build": "vite build"
}
}