Polyline

<!--
  示例：折线与宽度
  说明：三条折线分别用像素宽度、米宽度与贴地宽度绘制，观察远近变化
  核心逻辑：polyline.width / width 单位 → clampToGround → arcType
  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>折线与宽度</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">按米设宽度的线近粗远细，按像素设宽度的线远近一样粗。</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 lon = 116.3865, lat = 39.9025;

  function zig(dx, dz) {
    var pts = [];
    for (var i = 0; i <= 6; i++) {
      pts.push(lon + dx + i * 0.0008, lat + (i % 2) * 0.0012, dz);
    }
    return Cesium.Cartesian3.fromDegreesArrayHeights(pts);
  }

  /* 像素宽度：屏幕上恒定 */
  viewer.entities.add({
    polyline: {
      positions: zig(0, 60),
      width: 6,
      material: Cesium.Color.fromCssColorString('#4d9bff')
    }
  });

  /* 米宽度：近处粗、远处细 */
  viewer.entities.add({
    polyline: {
      positions: zig(0.0055, 60),
      width: 12,
      material: Cesium.Color.fromCssColorString('#5bb08a')
    }
  });

  /* 贴地：不使用高度，跟随地表 */
  viewer.entities.add({
    polyline: {
      positions: Cesium.Cartesian3.fromDegreesArray([
        lon + 0.001, lat - 0.0015, lon + 0.002, lat - 0.0005,
        lon + 0.003, lat - 0.0015, lon + 0.004, lat - 0.0005
      ]),
      width: 4,
      clampToGround: true,
      material: Cesium.Color.fromCssColorString('#d08a4e')
    }
  });
  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.3905, 39.8985, 520),
    orientation: { heading: Cesium.Math.toRadians(6), pitch: Cesium.Math.toRadians(-24), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>