Entity Drag

<!--
  示例：按住方块把它拖到新位置
  要点：LEFT_DOWN 拾取实体并锁住相机旋转，MOUSE_MOVE 改 position，LEFT_UP 解锁
  依赖：CesiumJS 1.121 · jsDelivr CDN，拖拽坐标来自射线与地表求交
-->
<!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>拖拽移动实体</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,.92);
       border:1px solid #2a313b;border-radius:6px;padding:9px 12px;font-size:12px;
       color:#a2a9b6;width:252px}
  .hud b{color:#e6e8ec;font-weight:600}
  .hud .row{margin-top:6px}
  .mono{font-family:ui-monospace,Consolas,monospace;font-size:11px;color:#8fb7e0}
  .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>拖动实体</b></div>
  <div class="row" id="state">按住方块拖动</div>
  <div class="row mono" id="pos">经度 — · 纬度 —</div>
  <div class="row">松开左键后相机恢复旋转</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;

  /* 三个可拖动的方块，各自带一个贴地投影点 */
  var BLOCKS = [
    { name: '甲', lng: 116.380, lat: 39.904, color: '#4d9bff' },
    { name: '乙', lng: 116.391, lat: 39.900, color: '#5fd0a8' },
    { name: '丙', lng: 116.401, lat: 39.907, color: '#ffb13d' }
  ];

  var boxes = [];

  BLOCKS.forEach(function (b) {
    var entity = viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(b.lng, b.lat, 130),
      box: {
        dimensions: new Cesium.Cartesian3(220, 220, 260),
        material: Cesium.Color.fromCssColorString(b.color).withAlpha(0.75),
        outline: true,
        outlineColor: Cesium.Color.fromCssColorString('#eaf2ff')
      },
      label: {
        text: b.name,
        font: '600 13px "Microsoft YaHei", sans-serif',
        fillColor: Cesium.Color.WHITE,
        pixelOffset: new Cesium.Cartesian2(0, -8),
        disableDepthTestDistance: Number.POSITIVE_INFINITY
      }
    });
    boxes.push(entity);
  });

  var handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);
  var dragging = null;
  var stateEl = document.getElementById('state');
  var posEl = document.getElementById('pos');

  function groundAt(windowPosition) {
    var ray = viewer.camera.getPickRay(windowPosition);
    return ray ? scene.globe.pick(ray, scene) : undefined;
  }

  handler.setInputAction(function (down) {
    var picked = scene.pick(down.position);
    if (!Cesium.defined(picked) || !Cesium.defined(picked.id) ||
        !Cesium.defined(picked.id.box)) {
      return;
    }
    dragging = picked.id;
    scene.screenSpaceCameraController.enableRotate = false;
    dragging.box.material = Cesium.Color.fromCssColorString('#ffd18a').withAlpha(0.35);
    stateEl.textContent = '正在拖动 ' + dragging.label.text.getValue(viewer.clock.currentTime);
  }, Cesium.ScreenSpaceEventType.LEFT_DOWN);

  handler.setInputAction(function (move) {
    if (!dragging) return;
    var p = groundAt(move.endPosition);
    if (!Cesium.defined(p)) return;

    var carto = Cesium.Cartographic.fromCartesian(p);
    /* 保持方块原本的离地高度，只改经纬度 */
    dragging.position = Cesium.Cartesian3.fromRadians(
      carto.longitude, carto.latitude, 130
    );
    posEl.textContent = '经度 ' + Cesium.Math.toDegrees(carto.longitude).toFixed(4) +
      ' · 纬度 ' + Cesium.Math.toDegrees(carto.latitude).toFixed(4);
  }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);

  handler.setInputAction(function () {
    if (!dragging) return;
    var idx = boxes.indexOf(dragging);
    dragging.box.material = Cesium.Color.fromCssColorString(
      BLOCKS[idx].color
    ).withAlpha(0.75);
    dragging = null;
    scene.screenSpaceCameraController.enableRotate = true;
    stateEl.textContent = '已放下，可继续拖动其他方块';
  }, Cesium.ScreenSpaceEventType.LEFT_UP);

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.372, 39.892, 2600),
    orientation: {
      heading: Cesium.Math.toRadians(22),
      pitch: Cesium.Math.toRadians(-36),
      roll: 0
    },
    duration: 0
  });
})();
</script>
</body>
</html>