3D Tiles Gaussian Splatting

<!--
  示例：泼溅渲染的体积感
  说明：六千个 16 像素、透明度 0.18 的彩色点堆成云团，相机缓慢环绕
  核心逻辑：PointPrimitiveCollection 批量加点 → HSL 按高度取色 → postRender 环绕相机
  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>泼溅渲染的体积感</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">云团由六千个半透明点叠成，单点几乎看不见，叠起来却有体积。相机在缓慢环绕。</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 pc = scene.primitives.add(new Cesium.PointPrimitiveCollection());
  var seed = 11;
  function rnd() { seed = (seed * 9301 + 49297) % 233280; return seed / 233280; }

  for (var i = 0; i < 6000; i++) {
    var r = Math.pow(rnd(), 0.6) * 0.0016;
    var a = rnd() * Math.PI * 2;
    var lon = 116.391 + Math.cos(a) * r;
    var lat = 39.907 + Math.sin(a) * r * 0.8;
    var h = Math.pow(rnd(), 1.6) * 30;
    pc.add({
      position: Cesium.Cartesian3.fromDegrees(lon, lat, h),
      pixelSize: 16,
      color: Cesium.Color.fromHsl(0.56 + rnd() * 0.1, 0.6, 0.4 + h / 30 * 0.35, 0.18)
    });
  }

  var center = Cesium.Cartesian3.fromDegrees(116.391, 39.907, 0);
  var enu = Cesium.Transforms.eastNorthUpToFixedFrame(center);

  scene.postRender.addEventListener(function () {
    var a = performance.now() * 0.00008;
    var p = Cesium.Matrix4.multiplyByPoint(enu,
      new Cesium.Cartesian3(Math.cos(a) * 260, Math.sin(a) * 260, 90), new Cesium.Cartesian3());
    viewer.camera.setView({
      destination: p,
      orientation: { heading: a + Math.PI / 2, pitch: Cesium.Math.toRadians(-18), roll: 0 }
    });
  });
})();
</script>
</body>
</html>