3D Tiles Performance Testing Dev

<!--
  示例：规模与帧率测试
  说明：六百栋建筑 + 实时帧率统计，展示实体规模对渲染性能的影响
  核心逻辑：伪随机生成 600 个盒体 → postRender 统计每秒帧数 → HUD 输出
  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>规模与帧率测试</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}
  .hud{position:absolute;left:12px;bottom:12px;z-index:5;background:rgba(23,28,35,.9);
       border:1px solid #2a313b;border-radius:6px;padding:6px 10px;font-size:12px;color:#a2a9b6}
</style>
</head>
<body>
<div id="c"></div>
<div class="tip">左下角是实时帧率。拖动视角时留意数值变化：实体越多，CPU 侧开销越大。</div>
<div id="hud" class="hud">FPS —</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 COUNT = 600;
  var seed = 99;
  function rnd() { seed = (seed * 9301 + 49297) % 233280; return seed / 233280; }

  for (var i = 0; i < COUNT; i++) {
    var lon = 116.3800 + rnd() * 0.0220;
    var lat = 39.9000 + rnd() * 0.0140;
    var h = 8 + rnd() * 52;
    var w = 8 + rnd() * 12;
    viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(lon, lat, h / 2),
      box: {
        dimensions: new Cesium.Cartesian3(w, w, h),
        material: Cesium.Color.fromHsl(0.58, 0.35, 0.35 + h / 60 * 0.25, 0.95)
      }
    });
  }

  var hud = document.getElementById('hud');
  var frames = 0, t0 = performance.now(), lastFps = 0;

  scene.postRender.addEventListener(function () {
    frames++;
    var now = performance.now();
    if (now - t0 >= 1000) {
      lastFps = frames * 1000 / (now - t0);
      frames = 0;
      t0 = now;
      hud.textContent = 'FPS ' + lastFps.toFixed(0) + ' · 实体 ' + COUNT;
    }
  });

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.3910, 39.8930, 2400),
    orientation: { heading: 0, pitch: Cesium.Math.toRadians(-38), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>