Video

<!--
  示例：视频贴到球面
  说明：把一段现场生成的动画视频贴到球体上，随时间循环播放
  核心逻辑：canvas.captureStream → video 元素 → 直接作为实体材质
  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>视频贴到球面</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">球面上的画面来自一个 video 元素，视频由 canvas 实时绘制。</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;

  /* 用 canvas 实时画出视频帧 */
  var src = document.createElement('canvas');
  src.width = 640; src.height = 360;
  var ctx = src.getContext('2d');
  var t = 0;

  function drawFrame() {
    t += 0.02;
    var g = ctx.createLinearGradient(0, 0, 640, 360);
    g.addColorStop(0, 'hsl(' + (200 + Math.sin(t) * 40) + ',55%,25%)');
    g.addColorStop(1, 'hsl(' + (30 + Math.cos(t) * 30) + ',60%,45%)');
    ctx.fillStyle = g;
    ctx.fillRect(0, 0, 640, 360);
    for (var i = 0; i < 24; i++) {
      var x = (i * 37 + t * 90) % 680 - 20;
      ctx.fillStyle = 'rgba(255,255,255,' + (0.1 + (i % 5) * 0.05) + ')';
      ctx.fillRect(x, 40 + (i % 7) * 36, 80, 6);
    }
    ctx.fillStyle = 'rgba(10,14,20,0.75)';
    ctx.fillRect(0, 300, 640, 60);
    ctx.fillStyle = '#e6e8ec';
    ctx.font = '600 26px sans-serif';
    ctx.fillText('实时视频帧 ' + t.toFixed(1) + 's', 24, 338);
    requestAnimationFrame(drawFrame);
  }
  drawFrame();

  /* canvas 流交给 video 元素，video 不必放进 DOM */
  var video = document.createElement('video');
  video.muted = true;
  video.loop = true;
  video.srcObject = src.captureStream(25);
  video.play();

  viewer.entities.add({
    position: Cesium.Cartesian3.fromDegrees(116.3905, 39.9035, 300),
    ellipsoid: {
      radii: new Cesium.Cartesian3(260, 260, 260),
      material: video       /* 实体材质可以直接接收 video 元素 */
    }
  });

  /* 底座，避免球体看起来像贴纸 */
  viewer.entities.add({
    position: Cesium.Cartesian3.fromDegrees(116.3905, 39.9035, 0),
    ellipse: {
      semiMajorAxis: 420, semiMinorAxis: 420,
      material: Cesium.Color.fromCssColorString('#1d2836').withAlpha(0.85),
      height: 1
    }
  });
  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.3835, 39.8998, 200),
    orientation: { heading: Cesium.Math.toRadians(42), pitch: Cesium.Math.toRadians(-6), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>