Animate Marker

<!--
  示例：标记沿路线移动
  核心逻辑：预先把路线重采样成等距点，rAF 里推进索引并 setLngLat
  数据：页面内构造的配送路线与 200 个采样点
  依赖：MapLibre GL JS 4 · jsDelivr CDN · demotiles 样式
-->
<!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>标记沿路线移动</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/maplibre-gl@4/dist/maplibre-gl.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;display:flex;gap:14px;align-items:center;padding:8px 12px;
       background:#f6f7f9;border-bottom:1px solid #e3e6ea;font-size:12px;color:#58606e;flex-wrap:wrap}
  .bar b{color:#16181d;font-weight:600}
  .bar input[type=range]{width:120px}
  .bar button{background:#fff;border:1px solid #cfd6df;border-radius:4px;padding:3px 10px;
       font:12px/1.4 inherit;color:#3a4250;cursor:pointer}
  .bar button:hover{border-color:#2e86de;color:#2e86de}
  #map{flex:1 1 auto;min-height:0}
</style>
</head>
<body>
<div class="bar">
  <span>进度 <b id="p">0%</b></span>
  <label>速度 <input id="s" type="range" min="0.2" max="3" step="0.1" value="1"> <b id="sv">1.0</b></label>
  <button id="play">暂停</button>
  <span>车辆按等距采样点匀速前进</span>
</div>
<div id="map"></div>
<script src="https://cdn.jsdelivr.net/npm/maplibre-gl@4/dist/maplibre-gl.js"></script>
<script>
(function () {
  'use strict';

  if (typeof maplibregl === 'undefined') {
    document.body.innerHTML =
      '<div style="padding:24px;color:#b42318">MapLibre 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }

  var path = [
    [116.20, 39.99], [117.10, 39.20], [117.60, 37.70],
    [118.60, 35.50], [119.60, 33.20], [120.60, 31.60],
    [121.47, 31.23], [119.80, 30.10], [117.20, 30.60],
    [115.30, 32.90], [116.20, 39.99]
  ];

  var map = new maplibregl.Map({
    container: 'map',
    style: 'https://demotiles.maplibre.org/style.json',
    center: [118, 35],
    zoom: 5.6,
    attributionControl: { compact: true, customAttribution: 'MapLibre demo tiles' }
  });

  map.addControl(new maplibregl.NavigationControl(), 'top-right');

  /* 按线段长度分配采样点数，得到近似等距的点列 */
  function resample(coords, total) {
    var segs = [];
    var sum = 0;
    var i;
    for (i = 0; i < coords.length - 1; i++) {
      var a = coords[i];
      var b = coords[i + 1];
      var d = Math.sqrt(Math.pow(b[0] - a[0], 2) + Math.pow(b[1] - a[1], 2));
      segs.push(d);
      sum += d;
    }

    var out = [];
    var target = i = 0;
    while (out.length < total && target <= sum) {
      var walk = 0;
      i = 0;
      while (i < segs.length && walk + segs[i] < target) {
        walk += segs[i];
        i++;
      }
      if (i >= coords.length - 1) break;
      var t = segs[i] === 0 ? 0 : (target - walk) / segs[i];
      out.push([
        coords[i][0] + (coords[i + 1][0] - coords[i][0]) * t,
        coords[i][1] + (coords[i + 1][1] - coords[i][1]) * t
      ]);
      target += sum / total;
    }
    return out;
  }

  var samples = resample(path, 200);
  var pEl = document.getElementById('p');

  var marker = new maplibregl.Marker({ color: '#e8590c', scale: 1.1 })
    .setLngLat(samples[0])
    .addTo(map);

  var popup = new maplibregl.Popup({ offset: 20, closeButton: false })
    .setHTML('配送中');

  marker.setPopup(popup);

  map.on('load', function () {
    map.addSource('route', {
      type: 'geojson',
      data: {
        type: 'FeatureCollection',
        features: [{
          type: 'Feature',
          properties: {},
          geometry: { type: 'LineString', coordinates: path }
        }]
      }
    });

    map.addLayer({
      id: 'route',
      type: 'line',
      source: 'route',
      layout: { 'line-cap': 'round', 'line-join': 'round' },
      paint: { 'line-color': '#e8590c', 'line-width': 3, 'line-opacity': 0.55 }
    });

    map.addSource('start', {
      type: 'geojson',
      data: {
        type: 'FeatureCollection',
        features: [
          { type: 'Feature', properties: { n: '起点' }, geometry: { type: 'Point', coordinates: path[0] } },
          { type: 'Feature', properties: { n: '终点' }, geometry: { type: 'Point', coordinates: path[path.length - 1] } }
        ]
      }
    });

    map.addLayer({
      id: 'ends',
      type: 'circle',
      source: 'start',
      paint: {
        'circle-radius': 6,
        'circle-color': '#2e86de',
        'circle-stroke-width': 2,
        'circle-stroke-color': '#ffffff'
      }
    });
  });

  var idx = 0;
  var speed = 1;
  var running = true;

  function tick() {
    if (running) {
      idx += 0.6 * speed;
      if (idx >= samples.length) idx = 0;
      var at = samples[Math.floor(idx)];
      marker.setLngLat(at);
      pEl.textContent = Math.round(idx / samples.length * 100) + '%';
    }
    requestAnimationFrame(tick);
  }
  requestAnimationFrame(tick);

  document.getElementById('s').addEventListener('input', function () {
    speed = parseFloat(this.value);
    document.getElementById('sv').textContent = speed.toFixed(1);
  });

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

  map.on('error', function (e) {
    if (e.error) console.warn('地图错误：' + e.error.message);
  });
})();
</script>
</body>
</html>