Example of using <code>ol.source.Cluster</code>.
This example shows how to do clustering on point features.
<!DOCTYPE html>
<html>
<head>
<title>Clustering example</title>
<script src="https://code.jquery.com/jquery-1.11.2.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="http://openlayers.org/en/v3.9.0/css/ol.css" type="text/css">
<script src="http://openlayers.org/en/v3.9.0/build/ol.js"></script>
</head>
<body>
<div class="container-fluid">
<div class="row-fluid">
<div class="span12">
<div id="map" class="map"></div>
</div>
</div>
</div>
<script>
var count = 20000;
var features = new Array(count);
var e = 4500000;
for (var i = 0; i < count; ++i) {
var coordinates = [2 * e * Math.random() - e, 2 * e * Math.random() - e];
features[i] = new ol.Feature(new ol.geom.Point(coordinates));
}
var source = new ol.source.Vector({
features: features
});
var clusterSource = new ol.source.Cluster({
distance: 40,
source: source
});
var styleCache = {};
var clusters = new ol.layer.Vector({
source: clusterSource,
style: function(feature, resolution) {
var size = feature.get('features').length;
var style = styleCache[size];
if (!style) {
style = [new ol.style.Style({
image: new ol.style.Circle({
radius: 10,
stroke: new ol.style.Stroke({
color: '#fff'
}),
fill: new ol.style.Fill({
color: '#3399CC'
})
}),
text: new ol.style.Text({
text: size.toString(),
fill: new ol.style.Fill({
color: '#fff'
})
})
})];
styleCache[size] = style;
}
return style;
}
});
var raster = new ol.layer.Tile({
source: new ol.source.MapQuest({layer: 'sat'})
});
var raw = new ol.layer.Vector({
source: source
});
var map = new ol.Map({
layers: [raster, clusters],
renderer: 'canvas',
target: 'map',
view: new ol.View({
center: [0, 0],
zoom: 2
})
});
</script>
</body>
</html>