OpenLayers示例代码：飞行动画
OpenLayers示例代码：飞行动画
<!DOCTYPE html>
<html>
<head>
<title>Flight Animation</title>
<link rel="stylesheet" href="https://openlayers.org/en/v4.0.1/css/ol.css" type="text/css">
<!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
<script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
<script src="https://openlayers.org/en/v4.0.1/build/ol.js"></script>
<script src="https://api.mapbox.com/mapbox.js/plugins/arc.js/v0.1.0/arc.js"></script>
</head>
<body>
<div id="map" class="map"></div>
<script>
var map = new ol.Map({
layers: [
new ol.layer.Tile({
source: new ol.source.Stamen({
layer: 'toner'
})
})
],
target: 'map',
view: new ol.View({
center: [0, 0],
zoom: 2
})
});
var style = new ol.style.Style({
stroke: new ol.style.Stroke({
color: '#EAE911',
width: 2
})
});
var flightsSource;
var addLater = function(feature, timeout) {
window.setTimeout(function() {
feature.set('start', new Date().getTime());
flightsSource.addFeature(feature);
}, timeout);
};
var pointsPerMs = 0.1;
var animateFlights = function(event) {
var vectorContext = event.vectorContext;
var frameState = event.frameState;
vectorContext.setStyle(style);
var features = flightsSource.getFeatures();
for (var i = 0; i < features.length; i++) {
var feature = features[i];
if (!feature.get('finished')) {
// only draw the lines for which the animation has not finished yet
var coords = feature.getGeometry().getCoordinates();
var elapsedTime = frameState.time - feature.get('start');
var elapsedPoints = elapsedTime * pointsPerMs;
if (elapsedPoints >= coords.length) {
feature.set('finished', true);
}
var maxIndex = Math.min(elapsedPoints, coords.length);
var currentLine = new ol.geom.LineString(coords.slice(0, maxIndex));
// directly draw the line with the vector context
vectorContext.drawGeometry(currentLine);
}
}
// tell OpenLayers to continue the animation
map.render();
};
flightsSource = new ol.source.Vector({
wrapX: false,
attributions: 'Flight data by ' +
'<a href="http://openflights.org/data.html">OpenFlights</a>,',
loader: function() {
var url = 'https://openlayers.org/en/v4.0.1/examples/data/openflights/flights.json';
fetch(url).then(function(response) {
return response.json();
}).then(function(json) {
var flightsData = json.flights;
for (var i = 0; i < flightsData.length; i++) {
var flight = flightsData[i];
var from = flight[0];
var to = flight[1];
// create an arc circle between the two locations
var arcGenerator = new arc.GreatCircle(
{x: from[1], y: from[0]},
{x: to[1], y: to[0]});
var arcLine = arcGenerator.Arc(100, {offset: 10});
if (arcLine.geometries.length === 1) {
var line = new ol.geom.LineString(arcLine.geometries[0].coords);
line.transform(ol.proj.get('EPSG:4326'), ol.proj.get('EPSG:3857'));
var feature = new ol.Feature({
geometry: line,
finished: false
});
// add the feature with a delay so that the animation
// for all features does not start at the same time
addLater(feature, i * 50);
}
}
map.on('postcompose', animateFlights);
});
}
});
var flightsLayer = new ol.layer.Vector({
source: flightsSource,
style: function(feature) {
// if the animation is still active for a feature, do not
// render the feature with the layer style
if (feature.get('finished')) {
return style;
} else {
return null;
}
}
});
map.addLayer(flightsLayer);
</script>
</body>
</html>
说明：
OpenLayers示例代码：飞行动画
