3D Tiles Feature Styling

<!--
  示例：按属性给要素换样式
  说明：24 栋建筑按高度分档，三套配色每 2.5 秒轮换
  核心逻辑：高度值存数组 → 样式函数返回 Color → 替换 box.material
  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>按属性给要素换样式</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">配色每 2.5 秒换一套：高度三分档 → 体量两分档 → 单色，循环往复。</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 seed = 5;
  function rnd() { seed = (seed * 9301 + 49297) % 233280; return seed / 233280; }

  var buildings = [];
  for (var i = 0; i < 24; i++) {
    var lon = 116.3862 + (i % 6) * 0.0019;
    var lat = 39.9032 + Math.floor(i / 6) * 0.0019;
    var h = 14 + rnd() * 62;
    var e = viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(lon, lat, h / 2),
      box: {
        dimensions: new Cesium.Cartesian3(24, 24, h),
        material: Cesium.Color.fromCssColorString('#5a677e'),
        outline: true,
        outlineColor: Cesium.Color.fromCssColorString('#0b0f14')
      }
    });
    buildings.push({ entity: e, h: h });
  }

  /* 三套样式：高度分档、类别色、单色 */
  var styles = [
    function (b) {
      var c = b.h > 55 ? '#ff5c5c' : (b.h > 35 ? '#ffb44d' : '#4d7cff');
      return Cesium.Color.fromCssColorString(c);
    },
    function (b) {
      return Cesium.Color.fromCssColorString(b.h > 40 ? '#a78bfa' : '#3ecf8e');
    },
    function () {
      return Cesium.Color.fromCssColorString('#7b8798');
    }
  ];

  var si = 0;
  function apply() {
    var fn = styles[si % styles.length];
    buildings.forEach(function (b) {
      b.entity.box.material = new Cesium.ColorMaterialProperty(fn(b));
    });
    si++;
    setTimeout(apply, 2500);
  }
  apply();

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.3910, 39.8998, 700),
    orientation: { heading: Cesium.Math.toRadians(10), pitch: Cesium.Math.toRadians(-28), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>