3D Tiles 1.1 Photogrammetry

<!--
  示例：用建筑群复现倾斜摄影的观感
  说明：官方示例加载 ion 上的倾斜摄影 3D Tiles；这里用代码生成的建筑群替代，保留相机环绕与光照感
  核心逻辑：伪随机建筑体块 → 地面多边形 → 相机绕场景旋转
  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>倾斜摄影场景的替代实现</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">相机绕建筑群缓缓环绕，模拟倾斜摄影常用的「飞一圈看体块」的浏览方式。建筑全部由代码生成。</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('#141c26');
  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 west = 116.383, south = 39.900, east = 116.399, north = 39.914;

  /* 地面 */
  viewer.entities.add({
    polygon: {
      hierarchy: new Cesium.PolygonHierarchy(
        Cesium.Cartesian3.fromDegreesArray([west, south, east, south, east, north, west, north])
      ),
      height: 0,
      material: Cesium.Color.fromCssColorString('#1b232e')
    }
  });

  /* 建筑群：8×8 网格，伪随机高度 */
  var seed = 21;
  function rnd() { seed = (seed * 9301 + 49297) % 233280; return seed / 233280; }
  var palette = ['#46536a', '#515f78', '#5c6b86', '#3d495d'];

  for (var r = 0; r < 8; r++) {
    for (var c = 0; c < 8; c++) {
      var lon = west + 0.0009 + c * 0.00185;
      var lat = south + 0.0009 + r * 0.0016;
      var h = 12 + rnd() * 58;
      var w = 18 + rnd() * 14;
      viewer.entities.add({
        position: Cesium.Cartesian3.fromDegrees(lon, lat, h / 2),
        box: {
          dimensions: new Cesium.Cartesian3(w, w, h),
          material: Cesium.Color.fromCssColorString(palette[(r + c) % palette.length]),
          outline: true,
          outlineColor: Cesium.Color.fromCssColorString('#0b0f14')
        }
      });
    }
  }

  /* 相机绕中心点转圈 */
  var center = Cesium.Cartesian3.fromDegrees(116.391, 39.907, 0);
  var radius = 900;
  var enu = Cesium.Transforms.eastNorthUpToFixedFrame(center);

  viewer.scene.postRender.addEventListener(function () {
    var a = performance.now() * 0.00012;
    var p = Cesium.Matrix4.multiplyByPoint(enu, new Cesium.Cartesian3(
      Math.cos(a) * radius, Math.sin(a) * radius, 380), new Cesium.Cartesian3());
    viewer.camera.setView({
      destination: p,
      orientation: {
        heading: a + Math.PI / 2,
        pitch: Cesium.Math.toRadians(-28),
        roll: 0
      }
    });
  });
})();
</script>
</body>
</html>