Rotatable 2D Map

<!--
  示例：可旋转的二维地图
  说明：平面地图整体缓慢旋转，方向标指示当前朝向
  核心逻辑：scene.mode = SCENE2D → camera.rotate(UNIT_Z) → 罗盘指示
  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>可旋转的二维地图</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}

  .needle{position:absolute;right:56px;top:56px;width:52px;height:52px;border-radius:50%;
          border:1px solid #2a313b;background:rgba(23,28,35,.9);color:#ffb13d;
          font:600 13px/52px sans-serif;text-align:center}
  .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">二维地图绕中心旋转，右上角的指针同步转动。</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;

  scene.mode = Cesium.SceneMode.SCENE2D;

  var lon = 116.3895, lat = 39.9035;
  for (var i = 0; i < 9; i++) {
    viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(lon + (i - 4) * 0.0011, lat, 0),
      box: {
        dimensions: new Cesium.Cartesian3(24, 24, 40),
        material: Cesium.Color.fromCssColorString('#5b6f86')
      }
    });
    viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(lon + (i - 4) * 0.0011, lat + 0.0016, 0),
      point: { pixelSize: 6, color: Cesium.Color.fromCssColorString('#ffb13d') }
    });
  }

  /* 方向指示：一根指针绕中心旋转 */
  var needle = document.createElement('div');
  needle.className = 'needle';
  needle.textContent = 'N';
  document.body.appendChild(needle);

  var angle = 0;
  scene.preRender.addEventListener(function () {
    angle += 0.004;
    viewer.camera.rotate(Cesium.Cartesian3.UNIT_Z, 0.004);
    needle.style.transform = 'translate(-50%,-50%) rotate(' + angle + 'rad)';
  });
  viewer.camera.flyTo({
    destination: Cesium.Rectangle.fromDegrees(116.3790, 39.8960, 116.4000, 39.9110),
    duration: 0
  });
})();
</script>
</body>
</html>