Custom Datasource

<!--
  示例：自己实现一个数据源，把外部数组接进 Cesium
  说明：重写 load 与 update，load 里建实体，update 每帧推进目标点位置
  核心逻辑：new CustomDataSource → 覆盖 load/update → viewer.dataSources.add
  依赖：CesiumJS 1.121 · jsDelivr CDN，数据在页面内定义
-->
<!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>自定义数据源</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/cesium@1.121.0/Build/Cesium/Widgets/widgets.css">
<style>
  html,body{height:100%;margin:0}
  body{background:#0e1116;color:#e6e8ec;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif}
  #c{height:100%}
  .hud{position:absolute;left:12px;top:12px;z-index:5;background:rgba(23,28,35,.9);
       border:1px solid #2a313b;border-radius:6px;padding:9px 12px;font-size:12px;
       color:#a2a9b6;max-width:260px}
  .hud b{color:#e6e8ec;font-weight:600}
  .hud .row{margin-top:7px}
  .cesium-viewer-bottom .cesium-widget-credits,.cesium-viewer-animationContainer,
  .cesium-viewer-timelineContainer{display:none!important}
</style>
</head>
<body>
<div id="c"></div>
<div class="hud">
  <div><b>自定义数据源</b></div>
  <div class="row">每条轨迹是一个独立实体组</div>
  <div class="row"><label><input id="show" type="checkbox" checked> 显示数据源</label></div>
  <div class="row" id="info">3 条轨迹 · 每帧由 update 推进</div>
</div>
<script src="https://cdn.jsdelivr.net/npm/cesium@1.121.0/Build/Cesium/Cesium.js"></script>
<script>
(function () {
  'use strict';

  var viewer = new Cesium.Viewer('c', {
    baseLayer: false,
    baseLayerPicker: false, geocoder: false, homeButton: false,
    sceneModePicker: false, navigationHelpButton: false,
    animation: false, timeline: false, fullscreenButton: false,
    infoBox: false, selectionIndicator: false
  });

  var scene = viewer.scene;
  scene.globe.baseColor = Cesium.Color.fromCssColorString('#1c2733');
  scene.backgroundColor = Cesium.Color.fromCssColorString('#0e1116');
  scene.skyBox.show = false;
  scene.moon.show = false;
  if (scene.skyAtmosphere) scene.skyAtmosphere.show = false;

  /* ---------- 数据：三条轨迹的中心、半径、速度 ---------- */
  var TRACKS = [
    { name: '轨迹 A', lon: 116.20, lat: 39.95, r: 0.05, speed: 0.35, color: '#4d9bff' },
    { name: '轨迹 B', lon: 116.55, lat: 39.90, r: 0.06, speed: 0.22, color: '#39c0a0' },
    { name: '轨迹 C', lon: 116.36, lat: 39.75, r: 0.04, speed: 0.5, color: '#f2a03d' }
  ];

  var dataSource = new Cesium.CustomDataSource('tracks');
  var movers = [];

  /* ---------- load：把外部数据变成实体 ---------- */
  dataSource.load = function (tracks) {
    var self = this;

    tracks.forEach(function (t) {
      var pts = [];
      for (var i = 0; i <= 64; i++) {
        var a = (i / 64) * Math.PI * 2;
        pts.push(t.lon + t.r * Math.cos(a), t.lat + t.r * 0.8 * Math.sin(a), 600);
      }

      self.entities.add({
        name: t.name + ' 路径',
        polyline: {
          positions: Cesium.Cartesian3.fromDegreesArrayHeights(pts),
          width: 2,
          material: Cesium.Color.fromCssColorString(t.color).withAlpha(0.45)
        }
      });

      var mover = self.entities.add({
        name: t.name,
        position: Cesium.Cartesian3.fromDegrees(t.lon + t.r, t.lat, 600),
        point: {
          pixelSize: 11,
          color: Cesium.Color.fromCssColorString(t.color),
          outlineColor: Cesium.Color.WHITE,
          outlineWidth: 2,
          disableDepthTestDistance: Number.POSITIVE_INFINITY
        },
        label: {
          text: t.name,
          font: '500 12px "Microsoft YaHei", sans-serif',
          fillColor: Cesium.Color.fromCssColorString(t.color),
          pixelOffset: new Cesium.Cartesian2(0, -20),
          disableDepthTestDistance: Number.POSITIVE_INFINITY
        }
      });

      movers.push({ track: t, entity: mover });
    });

    return Promise.resolve(self);
  };

  /* ---------- update：每帧被数据源显示循环调用 ---------- */
  var elapsed = 0;
  dataSource.update = function (time) {
    elapsed += 1 / 60;

    movers.forEach(function (m) {
      var a = elapsed * m.track.speed;
      m.entity.position = Cesium.Cartesian3.fromDegrees(
        m.track.lon + m.track.r * Math.cos(a),
        m.track.lat + m.track.r * 0.8 * Math.sin(a),
        600
      );
    });

    return true;
  };

  dataSource.load(TRACKS).then(function (ds) {
    viewer.dataSources.add(ds);
  });

  document.getElementById('show').addEventListener('change', function () {
    dataSource.show = this.checked;
  });

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.375, 39.845, 42000),
    orientation: {
      heading: 0,
      pitch: Cesium.Math.toRadians(-38),
      roll: 0
    },
    duration: 0
  });
})();
</script>
</body>
</html>