Mouse Pick

<!--
  示例：鼠标拾取经纬度并在地球上打点
  要点：ScreenSpaceEventHandler 监听移动与单击，pickEllipsoid 求交后转 Cartographic 输出
  依赖：CesiumJS 1.121 · jsDelivr CDN，无外部数据
-->
<!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>鼠标拾取坐标</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%}
  #c canvas{cursor:crosshair}
  .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:280px}
  .hud b{color:#e6e8ec;font-weight:600}
  .hud .row{margin-top:6px}
  .hud .val{color:#cfe4ff;font-family:Consolas,Menlo,monospace;font-size:12px}
  .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>拾取坐标</b></div>
  <div class="row">经度 <span class="val" id="lng">—</span></div>
  <div class="row">纬度 <span class="val" id="lat">—</span></div>
  <div class="row">高程 <span class="val" id="hgt">—</span></div>
  <div class="row">单击地球记录点位，最多保留 6 个</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;

  var lngEl = document.getElementById('lng');
  var latEl = document.getElementById('lat');
  var hgtEl = document.getElementById('hgt');

  function pickAt(windowPosition) {
    var cartesian = viewer.camera.pickEllipsoid(windowPosition, scene.globe.ellipsoid);
    if (!Cesium.defined(cartesian)) return null;
    return Cesium.Cartographic.fromCartesian(cartesian);
  }

  function show(carto) {
    if (!carto) {
      lngEl.textContent = '—';
      latEl.textContent = '—';
      hgtEl.textContent = '—';
      return;
    }
    lngEl.textContent = Cesium.Math.toDegrees(carto.longitude).toFixed(6);
    latEl.textContent = Cesium.Math.toDegrees(carto.latitude).toFixed(6);
    hgtEl.textContent = carto.height.toFixed(1) + ' m';
  }

  var marks = [];

  function addMark(carto) {
    var lng = Cesium.Math.toDegrees(carto.longitude);
    var lat = Cesium.Math.toDegrees(carto.latitude);
    var entity = viewer.entities.add({
      position: Cesium.Cartesian3.fromRadians(carto.longitude, carto.latitude, 0),
      point: {
        pixelSize: 8,
        color: Cesium.Color.fromCssColorString('#3fe0b0'),
        outlineColor: Cesium.Color.WHITE,
        outlineWidth: 1.5,
        disableDepthTestDistance: Number.POSITIVE_INFINITY
      },
      label: {
        text: lng.toFixed(4) + ', ' + lat.toFixed(4),
        font: '500 11px Consolas, monospace',
        fillColor: Cesium.Color.fromCssColorString('#3fe0b0'),
        pixelOffset: new Cesium.Cartesian2(0, -18),
        disableDepthTestDistance: Number.POSITIVE_INFINITY
      }
    });
    marks.push(entity);
    if (marks.length > 6) {
      viewer.entities.remove(marks.shift());
    }
  }

  var handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);

  handler.setInputAction(function (movement) {
    show(pickAt(movement.endPosition));
  }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);

  handler.setInputAction(function (click) {
    var carto = pickAt(click.position);
    if (!carto) return;
    show(carto);
    addMark(carto);
  }, Cesium.ScreenSpaceEventType.LEFT_CLICK);

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(108, 30, 9000000),
    orientation: { heading: 0, pitch: Cesium.Math.toRadians(-90), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>