Feature Move Animation

<!--
  示例：要素位移动画
  要点：按线要素长度换算进度，requestAnimationFrame 驱动点要素沿路线移动
  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>要素位移动画</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;color:#16181d}
  .bar{flex:0 0 auto;padding:8px 12px;background:#f6f7f9;border-bottom:1px solid #e3e6ea;
       display:flex;gap:12px;align-items:center;font-size:12px;color:#58606e;flex-wrap:wrap}
  .bar button{padding:4px 10px;border:1px solid #d5dae2;background:#fff;border-radius:4px;cursor:pointer}
  .bar input[type=range]{width:120px}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <button id="toggle">暂停</button>
  <label for="sp">速度 <b id="spv">1.0×</b></label>
  <input type="range" id="sp" min="0.2" max="3" step="0.1" value="1">
  <span>用时 <b id="eta">—</b></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 (!window.ol) {
    document.getElementById('map').textContent = 'OpenLayers 加载失败，请检查 cdn.jsdelivr.net 是否可访问';
    return;
  }
  var fromLonLat = ol.proj.fromLonLat;

  var path = [
    [116.286, 39.905], [116.320, 39.930], [116.352, 39.905], [116.386, 39.935],
    [116.418, 39.910], [116.452, 39.940], [116.486, 39.912], [116.520, 39.880]
  ].map(function (p) { return fromLonLat(p); });

  var route = new ol.geom.LineString(path);

  var routeFeature = new ol.Feature({ geometry: route });
  routeFeature.setStyle(new ol.style.Style({
    stroke: new ol.style.Stroke({ color: 'rgba(31,95,208,0.85)', width: 4 })
  }));

  var car = new ol.Feature({ geometry: new ol.geom.Point(path[0]) });
  car.setStyle(new ol.style.Style({
    image: new ol.style.Circle({
      radius: 8,
      fill: new ol.style.Fill({ color: '#b42318' }),
      stroke: new ol.style.Stroke({ color: '#ffffff', width: 2.5 })
    })
  }));

  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'}) }),
      new ol.layer.Vector({ source: new ol.source.Vector({ features: [routeFeature, car] }) })
    ],
    view: new ol.View({ center: fromLonLat([116.40, 39.915]), zoom: 12 }),
    controls: ol.control.defaults.defaults({ rotate: false })
  });

  /* 路线长度按地图单位（米）算，速度用它换算成进度增量 */
  var length = route.getLength();
  var speedMps = 24;        /* 基础速度 24 m/s 左右，便于肉眼观察 */
  var factor = 1;
  var progress = 0;
  var running = true;
  var last = 0;

  function frame(ts) {
    if (!last) last = ts;
    var dt = Math.min(0.1, (ts - last) / 1000);
    last = ts;

    if (running) {
      progress += (speedMps * factor * dt) / length;
      if (progress > 1) progress -= 1;
      car.getGeometry().setCoordinates(route.getCoordinateAt(progress));
    }

    var remain = (1 - progress) * length / (speedMps * factor);
    document.getElementById('eta').textContent = remain.toFixed(1) + ' 秒到终点';
    requestAnimationFrame(frame);
  }
  requestAnimationFrame(frame);

  document.getElementById('toggle').addEventListener('click', function () {
    running = !running;
    this.textContent = running ? '暂停' : '继续';
    last = 0;
  });

  document.getElementById('sp').addEventListener('input', function () {
    factor = Number(this.value);
    document.getElementById('spv').textContent = factor.toFixed(1) + '×';
  });
})();
</script>
</body>
</html>