Webgl Vector Layer

<!--
  示例：OpenLayers WebGL 矢量图层
  要点：WebGLVector 以字面量样式渲染面要素，用样式变量控制悬停高亮
  依赖：OpenLayers 10.3.1 · jsDelivr CDN
-->
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta name="robots" content="noindex,follow">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>WebGL 矢量图层</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/ol@10.3.1/ol.css">
<style>
  html,body{height:100%;margin:0}
  body{display:flex;flex-direction:column;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif}
  .bar{flex:0 0 auto;padding:8px 12px;background:#f6f7f9;border-bottom:1px solid #e3e6ea;
       display:flex;gap:10px;align-items:center;flex-wrap:wrap;font-size:12px;color:#58606e}
  .bar label{display:flex;gap:5px;align-items:center;cursor:pointer}
  .bar select,.bar input[type=range]{font-size:12px}
  .bar .val{font-family:ui-monospace,Consolas,monospace;color:#1f5fd0;min-width:44px}
  .bar .sep{width:1px;height:16px;background:#d8dce2}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <span>悬停区域查看名称</span>
  <span class="sep"></span>
  <span id="info">—</span>
</div>
<div id="map"></div>
<script src="https://cdn.jsdelivr.net/npm/ol@10.3.1/dist/ol.js"></script>
<script>
(function () {
  'use strict';

  if (typeof ol === 'undefined') {
    document.getElementById('map').textContent = 'OpenLayers 加载失败，请检查能否访问 cdn.jsdelivr.net';
    return;
  }


  var regions = [
    {name: '海淀', color: [169, 201, 236, 0.75], box: [116.14, 39.94, 116.34, 40.06]},
    {name: '朝阳', color: [183, 219, 178, 0.75], box: [116.44, 39.90, 116.62, 40.05]},
    {name: '西城', color: [239, 207, 159, 0.75], box: [116.32, 39.88, 116.40, 39.96]},
    {name: '东城', color: [232, 170, 191, 0.75], box: [116.40, 39.88, 116.48, 39.96]},
    {name: '丰台', color: [189, 175, 217, 0.75], box: [116.18, 39.78, 116.40, 39.88]},
    {name: '大兴', color: [158, 208, 201, 0.75], box: [116.28, 39.62, 116.56, 39.78]}
  ];

  var features = regions.map(function (region, index) {
    var b = region.box;
    var feature = new ol.Feature({
      geometry: new ol.geom.Polygon([[
        ol.proj.fromLonLat([b[0], b[1]]),
        ol.proj.fromLonLat([b[2], b[1]]),
        ol.proj.fromLonLat([b[2], b[3]]),
        ol.proj.fromLonLat([b[0], b[3]]),
        ol.proj.fromLonLat([b[0], b[1]])
      ]]),
      name: region.name,
      COLOR: region.color
    });
    feature.setId(index + 1);
    return feature;
  });

  var vectorLayer = new ol.layer.WebGLVector({
    source: new ol.source.Vector({features: features}),
    variables: {highlightedId: -1},
    style: {
      'fill-color': ['get', 'COLOR'],
      'stroke-color': [
        'case',
        ['==', ['var', 'highlightedId'], ['id']],
        'white',
        [80, 96, 112]
      ],
      'stroke-width': [
        'case',
        ['==', ['var', 'highlightedId'], ['id']],
        4,
        1.5
      ]
    }
  });

  var map = new ol.Map({
    target: 'map',
    layers: [
      new ol.layer.Tile({source: new ol.source.XYZ({url: 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}', attributions: 'Tiles © Esri'}), opacity: 0.4}),
      vectorLayer
    ],
    view: new ol.View({
      center: ol.proj.fromLonLat([116.39, 39.90]),
      zoom: 9
    })
  });

  var highlightedId = -1;

  function display(pixel) {
    var feature = map.forEachFeatureAtPixel(pixel, function (candidate) {
      return candidate;
    });
    document.getElementById('info').textContent =
      feature ? feature.get('name') : '—';
    var id = feature ? feature.getId() : -1;
    if (id !== highlightedId) {
      highlightedId = id;
      vectorLayer.updateStyleVariables({highlightedId: highlightedId});
    }
  }

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

  map.on('click', function (evt) {
    display(evt.pixel);
  });

})();
</script>
</body>
</html>