3D Tiles 1.1 S2 Globe

<!--
  示例：S2 网格与全球影像金字塔
  说明：三层不同密度的经纬网格叠在东亚上空，颜色由冷到暖表示层级加深
  核心逻辑：fromDegreesArrayHeights 生成抬高折线 → 循环画经纬线 → 相机退到 420 万米
  依赖：CesiumJS 1.121 · 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>S2 网格与全球影像金字塔</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%}
  .tip{position:absolute;left:12px;top:12px;z-index:5;
       background:rgba(23,28,35,.9);border:1px solid #2a313b;border-radius:6px;
       padding:8px 12px;font-size:12px;color:#a2a9b6;max-width:320px;line-height:1.6}
  .cesium-viewer-bottom .cesium-widget-credits,.cesium-viewer-animationContainer,
  .cesium-viewer-timelineContainer{display:none!important}

</style>
</head>
<body>
<div id="c"></div>
<div class="tip">三层网格依次是 4×4、8×8、16×16，对应影像金字塔的三级。网格抬高 3000 米以免与球面深度冲突。</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.sun.show = false;
  scene.moon.show = false;
  if (scene.skyAtmosphere) scene.skyAtmosphere.show = false;

  function grid(lon0, lat0, lon1, lat1, n, color) {
    var h = 3000;
    for (var i = 0; i <= n; i++) {
      var lon = lon0 + (lon1 - lon0) * i / n;
      var lat = lat0 + (lat1 - lat0) * i / n;
      viewer.entities.add({
        polyline: {
          positions: Cesium.Cartesian3.fromDegreesArrayHeights([lon, lat0, h, lon, lat1, h]),
          width: 1,
          material: color
        }
      });
      viewer.entities.add({
        polyline: {
          positions: Cesium.Cartesian3.fromDegreesArrayHeights([lon0, lat, h, lon1, lat, h]),
          width: 1,
          material: color
        }
      });
    }
  }

  grid(95, 20, 125, 45, 4, Cesium.Color.fromCssColorString('#2f6f8f'));
  grid(103, 27, 117, 38, 8, Cesium.Color.fromCssColorString('#4d9bff'));
  grid(107, 30, 113, 35, 16, Cesium.Color.fromCssColorString('#ffd166'));

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(110, 31, 4200000),
    orientation: { heading: 0, pitch: Cesium.Math.toRadians(-90), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>