Z Indexing Geometry

<!--
  示例：几何绘制顺序
  说明：三块重叠的地面多边形用不同 zIndex，压盖关系由序号决定
  核心逻辑：entity.zIndex → 地面多边形排序 → 与高度无关的压盖控制
  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>几何绘制顺序</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">三块面几乎在同一高度，谁盖住谁只看 zIndex，不看添加顺序。</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 patch(dx, dy, color, z) {
    var e = viewer.entities.add({
      polygon: {
        hierarchy: Cesium.Cartesian3.fromDegreesArray([
          116.384 + dx, 39.901 + dy,
          116.390 + dx, 39.901 + dy,
          116.390 + dx, 39.905 + dy,
          116.384 + dx, 39.905 + dy
        ]),
        material: Cesium.Color.fromCssColorString(color).withAlpha(0.85)
      }
    });
    e.zIndex = z;
    return e;
  }

  /* 故意先加最上层，再让 zIndex 决定最终顺序 */
  patch(0.0018, 0.0012, '#d08a4e', 3);
  patch(0.0000, 0.0000, '#3f6f9c', 1);
  patch(0.0009, 0.0006, '#5bb08a', 2);
  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.3895, 39.9000, 520),
    orientation: { heading: Cesium.Math.toRadians(0), pitch: Cesium.Math.toRadians(-46), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>