Debug Stats

<!--
  示例：把帧率、图元数量与相机高度摆在一个面板里
  要点：scene.debugShowFramesPerSecond 提供内置帧率，postRender 里读取场景统计
  依赖：CesiumJS 1.121 · jsDelivr CDN，统计对象由代码生成
-->
<!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>帧率与图元统计</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%}
  .hud{position:absolute;left:12px;top:12px;z-index:5;background:rgba(23,28,35,.93);
       border:1px solid #2a313b;border-radius:6px;padding:9px 12px;font-size:12px;
       color:#a2a9b6;width:262px}
  .hud b{color:#e6e8ec;font-weight:600}
  .hud .row{margin-top:7px}
  .kv{display:flex;justify-content:space-between;line-height:1.9}
  .kv span:first-child{color:#7f8896}
  .kv span:last-child{font-family:ui-monospace,Consolas,monospace;font-size:11px;color:#8fb7e0}
  .hud button{font:inherit;font-size:12px;padding:3px 9px;margin-right:4px;border-radius:4px;
       cursor:pointer;border:1px solid #343b46;background:#1d232b;color:#cfd6e2}
  .hud button.on{background:#1d3a5c;border-color:#3d6f9e;color:#cfe4ff}
  .cesium-viewer-bottom .cesium-widget-credits,.cesium-viewer-animationContainer,
  .cesium-viewer-timelineContainer{display:none!important}
</style>
</head>
<body>
<div id="c"></div>
<div class="hud">
  <div><b>运行统计</b></div>
  <div class="row">
    <div class="kv"><span>内置帧率</span><span id="fps">已开启</span></div>
    <div class="kv"><span>顶层图元</span><span id="prim">—</span></div>
    <div class="kv"><span>实体数量</span><span id="ent">—</span></div>
    <div class="kv"><span>后处理阶段</span><span id="stage">—</span></div>
    <div class="kv"><span>相机高度</span><span id="height">—</span></div>
  </div>
  <div class="row">
    <button id="fpsBtn" class="on">帧率</button>
    <button id="fogBtn" class="on">雾</button>
  </div>
</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;

  /* 打开内置帧率显示，会出现在画面右上角 */
  scene.debugShowFramesPerSecond = true;
  scene.fog.enabled = true;

  /* 一批箱体与一条贴地线，让统计数字有内容 */
  for (var i = 0; i < 8; i++) {
    viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(116.366 + i * 0.006, 39.904, 90),
      box: {
        dimensions: new Cesium.Cartesian3(140, 140, 180),
        material: Cesium.Color.fromCssColorString(i % 2 ? '#2f4a66' : '#3a5a72'),
        outline: true,
        outlineColor: Cesium.Color.fromCssColorString('#8fb7e0')
      }
    });
  }
  viewer.entities.add({
    polyline: {
      positions: Cesium.Cartesian3.fromDegreesArray([
        116.360, 39.896, 116.400, 39.896, 116.400, 39.912, 116.360, 39.912,
        116.360, 39.896
      ]),
      width: 2,
      material: new Cesium.PolylineDashMaterialProperty({
        color: Cesium.Color.fromCssColorString('#ffb13d'),
        dashLength: 18
      }),
      clampToGround: true
    }
  });

  var primEl = document.getElementById('prim');
  var entEl = document.getElementById('ent');
  var stageEl = document.getElementById('stage');
  var heightEl = document.getElementById('height');
  var frame = 0;
  var carto = new Cesium.Cartographic();

  scene.postRender.addEventListener(function () {
    if (++frame % 20 !== 0) return;
    primEl.textContent = scene.primitives.length;
    entEl.textContent = viewer.entities.values.length;
    stageEl.textContent = scene.postProcessStages.length;
    Cesium.Cartographic.fromCartesian(viewer.camera.positionWC, undefined, carto);
    heightEl.textContent = Math.round(carto.height) + ' 米';
  });

  document.getElementById('fpsBtn').addEventListener('click', function () {
    scene.debugShowFramesPerSecond = !scene.debugShowFramesPerSecond;
    this.className = scene.debugShowFramesPerSecond ? 'on' : '';
    document.getElementById('fps').textContent =
      scene.debugShowFramesPerSecond ? '已开启' : '已关闭';
  });

  document.getElementById('fogBtn').addEventListener('click', function () {
    scene.fog.enabled = !scene.fog.enabled;
    this.className = scene.fog.enabled ? 'on' : '';
  });

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.389, 39.876, 4200),
    orientation: {
      heading: 0,
      pitch: Cesium.Math.toRadians(-24),
      roll: 0
    },
    duration: 0
  });
})();
</script>
</body>
</html>