Projection

<!--
  示例：三维、二维与哥伦布视图
  说明：同一份数据在三维球体、平面地图与哥伦布视图之间切换
  核心逻辑：scene.mode = SCENE3D / SCENE2D / COLUMBUS_VIEW → 每 4 秒切换
  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>三维、二维与哥伦布视图</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}

  .info{position:absolute;right:12px;top:12px;background:rgba(23,28,35,.92);
        border:1px solid #2a313b;border-radius:6px;padding:8px 12px;font-size:12px;color:#cfe2f5}
  .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">三维是球体，二维是展开的平面，哥伦布视图是倾斜的平面。</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;

  var lon = 116.3895, lat = 39.9035;

  for (var i = 0; i < 7; i++) {
    viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(lon + (i - 3) * 0.0016, lat, 60),
      box: {
        dimensions: new Cesium.Cartesian3(30, 26, 120),
        material: Cesium.Color.fromCssColorString('#5d7186')
      }
    });
    viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(lon + (i - 3) * 0.0016, lat + 0.0018, 0),
      ellipse: {
        semiMajorAxis: 60, semiMinorAxis: 60,
        material: Cesium.Color.fromCssColorString('#d08a4e').withAlpha(0.8)
      }
    });
  }

  var modes = [
    Cesium.SceneMode.SCENE3D,
    Cesium.SceneMode.SCENE2D,
    Cesium.SceneMode.COLUMBUS_VIEW
  ];
  var names = ['三维球体', '二维平面', '哥伦布视图'];
  var idx = 0;

  var tag = document.createElement('div');
  tag.className = 'info';
  document.body.appendChild(tag);
  tag.textContent = names[0];

  setInterval(function () {
    idx = (idx + 1) % modes.length;
    scene.mode = modes[idx];
    tag.textContent = names[idx];
  }, 4000);
  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.3895, 39.9020, 520),
    orientation: { heading: 0, pitch: Cesium.Math.toRadians(-34), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>