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| import Map from 'ol/Map.js';
import OSM from 'ol/source/OSM.js';
import TileLayer from 'ol/layer/Tile.js';
import View from 'ol/View.js';
import {Circle as CircleStyle, Fill, Stroke, Style} from 'ol/style.js';
import {MultiPoint, Point} from 'ol/geom.js';
import {getVectorContext} from 'ol/render.js';
const tileLayer = new TileLayer({
source: new OSM(),
});
const map = new Map({
layers: [tileLayer],
target: 'map',
view: new View({
center: [0, 0],
zoom: 2,
}),
});
const imageStyle = new Style({
image: new CircleStyle({
radius: 5,
fill: new Fill({color: 'yellow'}),
stroke: new Stroke({color: 'red', width: 1}),
}),
});
const headInnerImageStyle = new Style({
image: new CircleStyle({
radius: 2,
fill: new Fill({color: 'blue'}),
}),
});
const headOuterImageStyle = new Style({
image: new CircleStyle({
radius: 5,
fill: new Fill({color: 'black'}),
}),
});
const n = 200;
const omegaTheta = 30000;
const R = 7e6;
const r = 2e6;
const p = 2e6;
tileLayer.on('postrender', function (event) {
const vectorContext = getVectorContext(event);
const frameState = event.frameState;
const theta = (2 * Math.PI * frameState.time) / omegaTheta;
const coordinates = [];
let i;
for (i = 0; i < n; ++i) {
const t = theta + (2 * Math.PI * i) / n;
const x = (R + r) * Math.cos(t) + p * Math.cos(((R + r) * t) / r);
const y = (R + r) * Math.sin(t) + p * Math.sin(((R + r) * t) / r);
coordinates.push([x, y]);
}
vectorContext.setStyle(imageStyle);
vectorContext.drawGeometry(new MultiPoint(coordinates));
const headPoint = new Point(coordinates[coordinates.length - 1]);
vectorContext.setStyle(headOuterImageStyle);
vectorContext.drawGeometry(headPoint);
vectorContext.setStyle(headInnerImageStyle);
vectorContext.drawGeometry(headPoint);
map.render();
});
map.render();
|
)
