Icon sprite with WebGL
In this example a sprite image is used for the icon styles. Using a sprite is required to get good performance with WebGL.
<!DOCTYPE html>
<html>
<head>
<title>Icon Sprites with WebGL</title>
<link rel="stylesheet" href="https://openlayers.org/en/v4.6.4/css/ol.css" type="text/css">
<!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
<script src=""></script>
<script src="https://openlayers.org/en/v4.6.4/build/ol.js"></script>
</head>
<body>
<div id="map" class="map"></div>
<div id="info"> </div>
<script>
var iconInfo = [{
offset: [0, 0],
opacity: 1.0,
rotateWithView: true,
rotation: 0.0,
scale: 1.0,
size: [55, 55]
}, {
offset: [110, 86],
opacity: 0.75,
rotateWithView: false,
rotation: Math.PI / 2.0,
scale: 1.25,
size: [55, 55]
}, {
offset: [55, 0],
opacity: 0.5,
rotateWithView: true,
rotation: Math.PI / 3.0,
scale: 1.5,
size: [55, 86]
}, {
offset: [212, 0],
opacity: 1.0,
rotateWithView: true,
rotation: 0.0,
scale: 1.0,
size: [44, 44]
}];
var i;
var iconCount = iconInfo.length;
var icons = new Array(iconCount);
for (i = 0; i < iconCount; ++i) {
var info = iconInfo[i];
icons[i] = new ol.style.Icon({
offset: info.offset,
opacity: info.opacity,
rotateWithView: info.rotateWithView,
rotation: info.rotation,
scale: info.scale,
size: info.size,
crossOrigin: 'anonymous',
src: 'https://openlayers.org/en/v4.6.4/examples/data/Butterfly.png'
});
}
var featureCount = 50000;
var features = new Array(featureCount);
var feature, geometry;
var e = 25000000;
for (i = 0; i < featureCount; ++i) {
geometry = new ol.geom.Point(
[2 * e * Math.random() - e, 2 * e * Math.random() - e]);
feature = new ol.Feature(geometry);
feature.setStyle(
new ol.style.Style({
image: icons[i % (iconCount - 1)]
})
);
features[i] = feature;
}
var vectorSource = new ol.source.Vector({
features: features
});
var vector = new ol.layer.Vector({
source: vectorSource
});
var map = new ol.Map({
renderer: /** @type {Array<ol.renderer.Type>} */ (['webgl', 'canvas']),
layers: [vector],
target: document.getElementById('map'),
view: new ol.View({
center: [0, 0],
zoom: 5
})
});
var overlayFeatures = [];
for (i = 0; i < featureCount; i += 30) {
var clone = features[i].clone();
clone.setStyle(null);
overlayFeatures.push(clone);
}
new ol.layer.Vector({
map: map,
source: new ol.source.Vector({
features: overlayFeatures
}),
style: new ol.style.Style({
image: icons[iconCount - 1]
})
});
map.on('click', function(evt) {
var info = document.getElementById('info');
info.innerHTML =
'Hold on a second, while I catch those butterflies for you ...';
window.setTimeout(function() {
var features = [];
map.forEachFeatureAtPixel(evt.pixel, function(feature) {
features.push(feature);
return false;
});
if (features.length === 1) {
info.innerHTML = 'Got one butterfly';
} else if (features.length > 1) {
info.innerHTML = 'Got ' + features.length + ' butterflies';
} else {
info.innerHTML = 'Couldn\'t catch a single butterfly';
}
}, 1);
});
map.on('pointermove', function(evt) {
if (evt.dragging) {
return;
}
var pixel = map.getEventPixel(evt.originalEvent);
var hit = map.hasFeatureAtPixel(pixel);
map.getTarget().style.cursor = hit ? 'pointer' : '';
});
</script>
</body>
</html>