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WebGL Vector Layer

vector82 geojson10 webgl18

 

Example of a vector layer rendered using WebGL

The ecoregions are loaded from a GeoJSON file.

main.js
import Map from 'ol/Map.js';
import View from 'ol/View.js';
import GeoJSON from 'ol/format/GeoJSON.js';
import TileLayer from 'ol/layer/WebGLTile.js';
import WebGLVectorLayer from 'ol/layer/WebGLVector.js';
import OSM from 'ol/source/OSM.js';
import VectorSource from 'ol/source/Vector.js';

const style = [
  {
    filter: ['==', ['var', 'highlightedId'], ['id']],
    style: {
      'stroke-color': 'white',
      'stroke-width': 3,
      'stroke-offset': -1,
      'fill-color': [255, 255, 255, 0.4],
    },
  },
  {
    else: true,
    style: {
      'stroke-color': ['*', ['get', 'COLOR'], [220, 220, 220]],
      'stroke-width': 2,
      'stroke-offset': -1,
      'fill-color': ['*', ['get', 'COLOR'], [255, 255, 255, 0.6]],
    },
  },
];

const osm = new TileLayer({
  source: new OSM(),
});

const vectorLayer = new WebGLVectorLayer({
  source: new VectorSource({
    url: 'https://openlayers.org/data/vector/ecoregions.json',
    format: new GeoJSON(),
  }),
  style,
  variables: {
    highlightedId: -1,
  },
});

const map = new Map({
  layers: [osm, vectorLayer],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 1,
  }),
});

let highlightedId = -1;
const displayFeatureInfo = function (pixel) {
  const feature = map.forEachFeatureAtPixel(pixel, function (feature) {
    return feature;
  });

  const info = document.getElementById('info');
  if (feature) {
    info.innerHTML = feature.get('ECO_NAME') || ' ';
  } else {
    info.innerHTML = ' ';
  }

  const id = feature ? feature.getId() : -1;
  if (id !== highlightedId) {
    highlightedId = id;
    vectorLayer.updateStyleVariables({highlightedId});
  }
};

map.on('pointermove', function (evt) {
  if (evt.dragging) {
    return;
  }
  displayFeatureInfo(evt.pixel);
});

map.on('click', function (evt) {
  displayFeatureInfo(evt.pixel);
});
index.html
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>WebGL Vector Layer</title>
    <link rel="stylesheet" href="node_modules/ol/ol.css">
    <style>
      .map {
        width: 100%;
        height: 400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <div id="info">&nbsp;</div>

    <script type="module" src="main.js"></script>
  </body>
</html>
package.json
{
  "name": "webgl-vector-layer",
  "dependencies": {
    "ol": "10.5.0"
  },
  "devDependencies": {
    "vite": "^3.2.3"
  },
  "scripts": {
    "start": "vite",
    "build": "vite build"
  }
}