Example of a map with a semi-transparent layer.
This example will display a tiled MaxBox layer semi-transparently over a MapQuest background.
<!DOCTYPE html>
<html>
<head>
<title>Semi-transparent layer 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 map = new ol.Map({
layers: [
new ol.layer.Tile({
source: new ol.source.MapQuest({layer: 'sat'})
}),
new ol.layer.Tile({
source: new ol.source.TileJSON({
url: 'http://api.tiles.mapbox.com/v3/mapbox.va-quake-aug.jsonp',
crossOrigin: 'anonymous'
})
})
],
target: 'map',
view: new ol.View({
center: ol.proj.fromLonLat([-77.93255, 37.9555]),
zoom: 5
})
});
</script>
</body>
</html>