OpenLayers示例代码：动态数据
OpenLayers示例代码：动态数据
<!DOCTYPE html>
<html>
<head>
<title>Dynamic Data</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>
</head>
<body>
<div id="map" class="map"></div>
<script>
var map = new ol.Map({
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
})
],
target: 'map',
view: new ol.View({
center: [0, 0],
zoom: 2
})
});
var imageStyle = new ol.style.Style({
image: new ol.style.Circle({
radius: 5,
snapToPixel: false,
fill: new ol.style.Fill({color: 'yellow'}),
stroke: new ol.style.Stroke({color: 'red', width: 1})
})
});
var headInnerImageStyle = new ol.style.Style({
image: new ol.style.Circle({
radius: 2,
snapToPixel: false,
fill: new ol.style.Fill({color: 'blue'})
})
});
var headOuterImageStyle = new ol.style.Style({
image: new ol.style.Circle({
radius: 5,
snapToPixel: false,
fill: new ol.style.Fill({color: 'black'})
})
});
var n = 200;
var omegaTheta = 30000; // Rotation period in ms
var R = 7e6;
var r = 2e6;
var p = 2e6;
map.on('postcompose', function(event) {
var vectorContext = event.vectorContext;
var frameState = event.frameState;
var theta = 2 * Math.PI * frameState.time / omegaTheta;
var coordinates = [];
var i;
for (i = 0; i < n; ++i) {
var t = theta + 2 * Math.PI * i / n;
var x = (R + r) * Math.cos(t) + p * Math.cos((R + r) * t / r);
var y = (R + r) * Math.sin(t) + p * Math.sin((R + r) * t / r);
coordinates.push([x, y]);
}
vectorContext.setStyle(imageStyle);
vectorContext.drawGeometry(new ol.geom.MultiPoint(coordinates));
var headPoint = new ol.geom.Point(coordinates[coordinates.length - 1]);
vectorContext.setStyle(headOuterImageStyle);
vectorContext.drawGeometry(headPoint);
vectorContext.setStyle(headInnerImageStyle);
vectorContext.drawGeometry(headPoint);
map.render();
});
map.render();
</script>
</body>
</html>
说明：
OpenLayers示例代码：动态数据
