3D Tiles Gaussian Splatting Comparison

<!--
  示例：泼溅与点云的参数对比
  说明：左右两组点云分别使用大点低透明与小点高不透明的参数，并加文字标注
  核心逻辑：封装 cloud(lon, size, alpha, color) → 两组不同参数 → label 标注
  依赖：CesiumJS 1.121 · jsDelivr CDN
-->
<!DOCTYPE html>
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<head>
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<meta name="viewport" content="width=device-width, initial-scale=1">
<title>泼溅与点云的参数对比</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">左边点大而透明，像雾；右边点小而实，像砂砾。两组点数相同，只差两个参数。</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 cloud(lon, size, alpha, color) {
    var seed = 41 + lon * 1000 | 0;
    function rnd() { seed = (seed * 9301 + 49297) % 233280; return seed / 233280; }
    var pc = scene.primitives.add(new Cesium.PointPrimitiveCollection());
    for (var i = 0; i < 3500; i++) {
      var r = Math.pow(rnd(), 0.6) * 0.0012;
      var a = rnd() * Math.PI * 2;
      pc.add({
        position: Cesium.Cartesian3.fromDegrees(
          lon + Math.cos(a) * r, 39.907 + Math.sin(a) * r, Math.pow(rnd(), 1.5) * 26),
        pixelSize: size,
        color: Cesium.Color.fromCssColorString(color).withAlpha(alpha)
      });
    }
    return pc;
  }

  cloud(116.3894, 20, 0.16, '#4d9bff');   /* 左侧：大点低透明度 */
  cloud(116.3926, 3,  0.85, '#ffb44d');   /* 右侧：小点高不透明度 */

  function label(lon, text) {
    viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(lon, 39.9102, 0),
      label: {
        text: text,
        font: '600 14px sans-serif',
        fillColor: Cesium.Color.WHITE,
        showBackground: true,
        backgroundColor: Cesium.Color.fromCssColorString('#1b232e').withAlpha(0.85),
        pixelOffset: new Cesium.Cartesian2(0, -8)
      }
    });
  }
  label(116.3894, '大点 · 低透明');
  label(116.3926, '小点 · 高不透明');

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.391, 39.8998, 300),
    orientation: { heading: 0, pitch: Cesium.Math.toRadians(-14), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>