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index.html
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index.html
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<head>
<style>
body { margin: 0; }
#time-log {
position: absolute;
font-size: 12px;
font-family: sans-serif;
padding: 5px;
border-radius: 3px;
background-color: rgba(200, 200, 200, 0.1);
color: lavender;
bottom: 10px;
right: 10px;
}
</style>
<script src="//unpkg.com/satellite.js/dist/satellite.min.js"></script>
<script src="//unpkg.com/globe.gl"></script>
<!-- <script src="../../dist/globe.gl.js"></script>-->
</head>
<body>
<div id="chart"></div>
<div id="time-log"></div>
<script type="module">
import * as THREE from '//unpkg.com/three/build/three.module.js';
const EARTH_RADIUS_KM = 6371; // km
const SAT_SIZE = 100; // km
const TIME_STEP = 3 * 1000; // per frame
const timeLogger = document.getElementById('time-log');
const world = Globe()
(document.getElementById('chart'))
.globeImageUrl('//unpkg.com/three-globe/example/img/earth-blue-marble.jpg')
.objectLat('lat')
.objectLng('lng')
.objectAltitude('alt')
.objectFacesSurface(false)
.objectLabel('name');
setTimeout(() => world.pointOfView({ altitude: 3.5 }));
const satGeometry = new THREE.OctahedronGeometry(SAT_SIZE * world.getGlobeRadius() / EARTH_RADIUS_KM / 2, 0);
const satMaterial = new THREE.MeshLambertMaterial({ color: 'palegreen', transparent: true, opacity: 0.7 });
world.objectThreeObject(() => new THREE.Mesh(satGeometry, satMaterial));
fetch('../datasets/space-track-leo.txt').then(r => r.text()).then(rawData => {
const tleData = rawData.replace(/\r/g, '')
.split(/\n(?=[^12])/)
.filter(d => d)
.map(tle => tle.split('\n'));
const satData = tleData.map(([name, ...tle]) => ({
satrec: satellite.twoline2satrec(...tle),
name: name.trim().replace(/^0 /, '')
}))
// exclude those that can't be propagated
.filter(d => !!satellite.propagate(d.satrec, new Date()).position)
.slice(0, 2000);
// time ticker
let time = new Date();
(function frameTicker() {
requestAnimationFrame(frameTicker);
time = new Date(+time + TIME_STEP);
timeLogger.innerText = time.toString();
// Update satellite positions
const gmst = satellite.gstime(time);
satData.forEach(d => {
const eci = satellite.propagate(d.satrec, time);
if (eci.position) {
const gdPos = satellite.eciToGeodetic(eci.position, gmst);
d.lat = satellite.radiansToDegrees(gdPos.latitude);
d.lng = satellite.radiansToDegrees(gdPos.longitude);
d.alt = gdPos.height / EARTH_RADIUS_KM
}
});
world.objectsData(satData);
})();
});
</script>
</body>