Feature Animation

<!--
  说明：自定义要素动画的中文示例，数据在页面内生成，可独立运行。
  核心逻辑：requestAnimationFrame + geometry.setCoordinates + map.render
  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>自定义要素动画</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 button{font:inherit;padding:3px 9px;border:1px solid #c9ced6;background:#fff;
       border-radius:5px;cursor:pointer;color:#333}
  .bar button:hover{background:#eef2f8}
  .bar input[type=range]{width:110px;vertical-align:middle}
  .bar input[type=text]{font:inherit;padding:2px 6px;border:1px solid #c9ced6;border-radius:4px}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3;position:relative}
  .panel{flex:0 0 auto;max-height:34%;overflow:auto;padding:8px 12px;font-size:12px;
       background:#fff;border-top:1px solid #e3e6ea;color:#3d4451}
  .panel pre{margin:0;font-family:Consolas,"Courier New",monospace;font-size:11px;
       white-space:pre-wrap;word-break:break-all;line-height:1.5}
  .ol-attribution{font-size:11px}

</style>
</head>
<body>
<div class="bar">
<button id="play" type="button">播放</button>
<button id="stop" type="button">暂停</button>
<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') {
    var errBox = document.getElementById('map');
    if (errBox) {
      errBox.innerHTML = '<div style="padding:20px;color:#b42318">OpenLayers 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    }
    return;
  }

  var fromLonLat = ol.proj.fromLonLat;
  var pivot = fromLonLat([116.375, 39.93]);
  var baseRing = [
    [116.300, 39.870], [116.450, 39.870], [116.450, 39.990], [116.300, 39.990], [116.300, 39.870]
  ].map(function (c) { return fromLonLat(c); });

  var marker = new ol.Feature({geometry: new ol.geom.Point(pivot)});
  var polygon = new ol.Feature({geometry: new ol.geom.Polygon([baseRing.slice()])});

  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'})}),
      new ol.layer.Vector({
        source: new ol.source.Vector({features: [polygon]}),
        style: new ol.style.Style({
          fill: new ol.style.Fill({color: 'rgba(31,95,208,0.12)'}),
          stroke: new ol.style.Stroke({color: '#1f5fd0', width: 2})
        })
      }),
      new ol.layer.Vector({
        source: new ol.source.Vector({features: [marker]}),
        style: new ol.style.Style({
          image: new ol.style.Circle({
            radius: 7,
            fill: new ol.style.Fill({color: '#ee602a'}),
            stroke: new ol.style.Stroke({color: '#ffffff', width: 2})
          })
        })
      })
    ],
    view: new ol.View({center: pivot, zoom: 11}),
    controls: ol.control.defaults.defaults({attribution: false, zoom: true, rotate: false})
  });

  var info = document.getElementById('info');
  var elapsed = 0;
  var last = 0;
  var raf = null;

  function update() {
    var angle = elapsed / 900;
    marker.getGeometry().setCoordinates(
      fromLonLat([116.35 + 0.05 * Math.cos(angle), 39.93 + 0.035 * Math.sin(angle)])
    );

    var ring = baseRing.map(function (c) {
      return ol.coordinate.rotate(c, angle * 0.8, pivot);
    });
    polygon.getGeometry().setCoordinates([ring]);
    info.textContent = '运行 ' + (elapsed / 1000).toFixed(1) + ' s · 角度 ' +
      ((angle * 0.8) * 180 / Math.PI % 360).toFixed(0) + '°';
  }

  function frame(now) {
    if (!last) { last = now; }
    elapsed += Math.min(60, now - last);
    last = now;
    update();
    map.render();
    raf = requestAnimationFrame(frame);
  }

  function start() {
    if (raf) { return; }
    last = 0;
    raf = requestAnimationFrame(frame);
  }

  function stop() {
    cancelAnimationFrame(raf);
    raf = null;
  }

  document.getElementById('play').addEventListener('click', start);
  document.getElementById('stop').addEventListener('click', stop);

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