Billboards

<!--
  示例：用 canvas 画图标并作为 billboard 标注城市
  说明：图标在内存中绘制成 dataURL，挂在 billboard 上，演示 scale、verticalOrigin 与贴地
  核心逻辑：canvas 画水滴标记 → dataURL → 每个城市一个 Entity(billboard + label)
  依赖：CesiumJS 1.121 · jsDelivr CDN，无外部图标文件
-->
<!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>公告板图标</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%}
  .hud{position:absolute;left:12px;top:12px;z-index:5;background:rgba(23,28,35,.9);
       border:1px solid #2a313b;border-radius:6px;padding:9px 12px;font-size:12px;
       color:#a2a9b6;max-width:250px}
  .hud b{color:#e6e8ec;font-weight:600}
  .hud .row{margin-top:7px}
  input[type=range]{width:100%}
  .cesium-viewer-bottom .cesium-widget-credits,.cesium-viewer-animationContainer,
  .cesium-viewer-timelineContainer{display:none!important}
</style>
</head>
<body>
<div id="c"></div>
<div class="hud">
  <div><b>公告板图标</b></div>
  <div class="row">图标缩放 <span id="sVal">1.0</span></div>
  <div class="row"><input id="s" type="range" min="0.4" max="2.4" step="0.1" value="1"></div>
  <div class="row"><label><input id="clamp" type="checkbox" checked> 底部贴地</label></div>
</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;

  /* ---------- 画一个水滴形标记 ---------- */
  function makeIcon(fill) {
    var w = 64, h = 84;
    var canvas = document.createElement('canvas');
    canvas.width = w;
    canvas.height = h;
    var g = canvas.getContext('2d');

    g.beginPath();
    g.arc(w / 2, 32, 22, Math.PI * 0.85, Math.PI * 2.15);
    g.lineTo(w / 2, h - 8);
    g.closePath();
    g.fillStyle = fill;
    g.fill();
    g.lineWidth = 4;
    g.strokeStyle = 'rgba(255,255,255,.92)';
    g.stroke();

    g.beginPath();
    g.arc(w / 2, 32, 9, 0, Math.PI * 2);
    g.fillStyle = 'rgba(255,255,255,.85)';
    g.fill();

    return canvas.toDataURL('image/png');
  }

  var ICONS = ['#4d9bff', '#39c0a0', '#f2a03d', '#e45c7a', '#8e7cf0', '#3fb6e8'];
  var cities = [
    [116.391263, 39.907359, '北京'],
    [121.473701, 31.230416, '上海'],
    [113.264385, 23.129112, '广州'],
    [104.066541, 30.572269, '成都'],
    [87.616848, 43.825592, '乌鲁木齐'],
    [126.642464, 45.756967, '哈尔滨']
  ];

  var billboards = [];

  cities.forEach(function (c, i) {
    var entity = viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(c[0], c[1], 0),
      billboard: {
        image: makeIcon(ICONS[i % ICONS.length]),
        scale: 1,
        verticalOrigin: Cesium.VerticalOrigin.BOTTOM,
        heightReference: Cesium.HeightReference.CLAMP_TO_GROUND,
        disableDepthTestDistance: Number.POSITIVE_INFINITY
      },
      label: {
        text: c[2],
        font: '500 13px "Microsoft YaHei", sans-serif',
        fillColor: Cesium.Color.WHITE,
        outlineColor: Cesium.Color.fromCssColorString('#0e1116'),
        outlineWidth: 3,
        style: Cesium.LabelStyle.FILL_AND_OUTLINE,
        verticalOrigin: Cesium.VerticalOrigin.TOP,
        pixelOffset: new Cesium.Cartesian2(0, 4),
        disableDepthTestDistance: Number.POSITIVE_INFINITY
      }
    });
    billboards.push(entity);
  });

  document.getElementById('s').addEventListener('input', function () {
    var v = parseFloat(this.value);
    document.getElementById('sVal').textContent = v.toFixed(1);
    billboards.forEach(function (e) { e.billboard.scale = v; });
  });

  document.getElementById('clamp').addEventListener('change', function () {
    var ref = this.checked
      ? Cesium.HeightReference.CLAMP_TO_GROUND
      : Cesium.HeightReference.NONE;
    billboards.forEach(function (e) { e.billboard.heightReference = ref; });
  });

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(110, 33, 6200000),
    orientation: {
      heading: 0,
      pitch: Cesium.Math.toRadians(-90),
      roll: 0
    },
    duration: 0
  });
})();
</script>
</body>
</html>