Webgl Tile Style

<!--
  示例：OpenLayers WebGL 瓦片调色
  要点：WebGLTile 的 exposure、contrast、saturation 样式变量实时作用于瓦片像素
  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 瓦片调色</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">
  <label>曝光 <input type="range" id="exposure" min="-1" max="1" step="0.05" value="0"><span class="val" id="exposure-value">0.00</span></label>
  <label>对比度 <input type="range" id="contrast" min="-1" max="1" step="0.05" value="0"><span class="val" id="contrast-value">0.00</span></label>
  <label>饱和度 <input type="range" id="saturation" min="-1" max="1" step="0.05" value="0"><span class="val" id="saturation-value">0.00</span></label>
</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 variables = {
    exposure: 0,
    contrast: 0,
    saturation: 0
  };

  var layer = new ol.layer.WebGLTile({
    source: new ol.source.XYZ({url: 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}', attributions: 'Tiles © Esri'}),
    style: {
      exposure: ['var', 'exposure'],
      contrast: ['var', 'contrast'],
      saturation: ['var', 'saturation'],
      variables: variables
    }
  });

  var map = new ol.Map({
    target: 'map',
    layers: [layer],
    view: new ol.View({
      center: ol.proj.fromLonLat([116.391, 39.907]),
      zoom: 9
    })
  });

  Object.keys(variables).forEach(function (name) {
    var control = document.getElementById(name);
    var output = document.getElementById(name + '-value');
    control.addEventListener('input', function () {
      var value = parseFloat(control.value);
      output.textContent = value.toFixed(2);
      var updates = {};
      updates[name] = value;
      layer.updateStyleVariables(updates);
    });
  });

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