65 lines
1.5 KiB
JavaScript
65 lines
1.5 KiB
JavaScript
import {Map, View} from '../src/ol/index.js';
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import {Point} from '../src/ol/geom.js';
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import TileLayer from '../src/ol/layer/Tile.js';
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import Stamen from '../src/ol/source/Stamen.js';
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import {Circle, Fill, Style} from '../src/ol/style.js';
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import {getVectorContext} from '../src/ol/render.js';
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import {useGeographic} from '../src/ol/proj.js';
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import {upAndDown} from '../src/ol/easing.js';
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useGeographic();
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const layer = new TileLayer({
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source: new Stamen({
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layer: 'toner'
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})
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});
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const map = new Map({
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layers: [layer],
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target: 'map',
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view: new View({
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center: [0, 0],
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zoom: 2
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})
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});
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const image = new Circle({
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radius: 8,
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fill: new Fill({color: 'rgb(255, 153, 0)'})
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});
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const style = new Style({
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image: image
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});
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const n = 1000;
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const geometries = new Array(n);
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for (let i = 0; i < n; ++i) {
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const lon = 360 * Math.random() - 180;
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const lat = 180 * Math.random() - 90;
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geometries[i] = new Point([lon, lat]);
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}
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layer.on('postrender', function(event) {
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const vectorContext = getVectorContext(event);
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for (let i = 0; i < n; ++i) {
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const importance = upAndDown(Math.pow((n - i) / n, 0.15));
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if (importance < 0.1) {
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continue;
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}
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image.setOpacity(importance);
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image.setScale(importance);
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vectorContext.setStyle(style);
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vectorContext.drawGeometry(geometries[i]);
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}
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const lon = 360 * Math.random() - 180;
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const lat = 180 * Math.random() - 90;
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geometries.push(new Point([lon, lat]));
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geometries.shift();
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map.render();
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});
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