Flight Animation

<!--
  说明：飞行动画
  核心逻辑：按进度取航线坐标推进飞机，追加尾迹并用 view.setCenter 跟随
  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>飞行动画</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;font-size:12px;color:#58606e;flex-wrap:wrap}
  .bar button{font:inherit;padding:4px 10px;border:1px solid #c9d0da;border-radius:5px;
              background:#fff;color:#1f2a37;cursor:pointer}
  #info{margin-left:auto}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <button id="play">起飞</button>
  <button id="reset">重置</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') {
    document.getElementById('map').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 routeLonLat = [
    [116.391, 39.907], [113.30, 40.10], [110.00, 38.50],
    [107.00, 36.00], [103.80, 36.06], [101.80, 36.62]
  ];
  var route = new ol.geom.LineString(routeLonLat.map(fromLonLat));

  var trail = new ol.geom.LineString([route.getCoordinateAt(0)]);
  var trailFeature = new ol.Feature({ geometry: trail });

  var plane = new ol.Feature({ geometry: new ol.geom.Point(route.getCoordinateAt(0)) });
  plane.set('rot', 0);

  var source = new ol.source.Vector({ features: [trailFeature, plane] });

  var layer = new ol.layer.Vector({
    source: source,
    style: function (feature) {
      if (feature === trailFeature) {
        return new ol.style.Style({
          stroke: new ol.style.Stroke({ color: 'rgba(226,110,40,0.65)', width: 3 })
        });
      }
      return new ol.style.Style({
        image: new ol.style.RegularShape({
          points: 3,
          radius: 10,
          rotation: feature.get('rot'),
          fill: new ol.style.Fill({ color: '#c8281c' }),
          stroke: new ol.style.Stroke({ color: '#ffffff', width: 2 })
        })
      });
    }
  });

  var view = new ol.View({ center: fromLonLat([116.391, 39.907]), zoom: 6, minZoom: 3, maxZoom: 19 });

  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'}) }), layer],
    view: view,
    controls: ol.control.defaults.defaults({ attribution: false, rotate: false })
  });

  var info = document.getElementById('info');
  var progress = 0;
  var running = false;
  var timer = null;
  var distanceKm = ol.sphere.getLength(route) / 1000;

  function draw() {
    var coord = route.getCoordinateAt(progress);
    var ahead = route.getCoordinateAt(Math.min(progress + 0.002, 1));
    var dx = ahead[0] - coord[0];
    var dy = ahead[1] - coord[1];
    var rot = Math.atan2(dy, dx) + Math.PI / 2;

    plane.getGeometry().setCoordinates(coord);
    plane.set('rot', rot);

    var coords = trail.getCoordinates();
    if (coords.length === 0 || ol.coordinate.squaredDistance(coords[coords.length - 1], coord) > 1) {
      coords.push(coord);
      trail.setCoordinates(coords);
    }

    view.setCenter(coord);
    info.textContent = '进度 ' + Math.round(progress * 100) + '% · 全程约 ' +
      Math.round(distanceKm) + ' km';
  }

  function tick() {
    if (!running) return;
    progress += 0.0018;
    if (progress >= 1) {
      progress = 1;
      running = false;
      document.getElementById('play').textContent = '起飞';
    }
    draw();
  }

  document.getElementById('play').addEventListener('click', function () {
    running = !running;
    this.textContent = running ? '暂停' : '起飞';
    if (running && progress >= 1) progress = 0;
    if (running) {
      clearInterval(timer);
      timer = setInterval(tick, 30);
    } else {
      clearInterval(timer);
    }
  });

  document.getElementById('reset').addEventListener('click', function () {
    clearInterval(timer);
    running = false;
    progress = 0;
    document.getElementById('play').textContent = '起飞';
    trail.setCoordinates([route.getCoordinateAt(0)]);
    draw();
    view.setCenter(route.getCoordinateAt(0));
    view.setZoom(6);
  });

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