Camera Set View

<!--
  示例：用 setView 与 lookAt 固定观察位置
  要点：setView 直接给相机位姿，lookAt 以目标点加距离与角度反推相机
  依赖：CesiumJS 1.121 · jsDelivr CDN，无外部资源
-->
<!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>定点视角</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:260px}
  .hud b{color:#e6e8ec;font-weight:600}
  .hud .row{margin-top:6px}
  .hud button{font:inherit;font-size:12px;padding:3px 9px;margin:0 4px 4px 0;border-radius:4px;
       cursor:pointer;border:1px solid #343b46;background:#1d232b;color:#cfd6e2}
  .hud button.on{background:#1d3a5c;border-color:#3d6f9e;color:#cfe4ff}
  .mono{font-family:ui-monospace,Consolas,monospace;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>setView 定点</b></div>
  <div class="row">
    <button id="p0" class="on">全球</button>
    <button id="p1">城市</button>
    <button id="p2">贴近</button>
  </div>
  <div class="row"><button id="p3">lookAt 目标点</button></div>
  <div class="row mono" id="cam">高 — · 航向 —</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 TARGET = Cesium.Cartesian3.fromDegrees(116.389, 39.906, 0);

  /* 一个方尖碑式的地标，作为观察对象 */
  viewer.entities.add({
    position: Cesium.Cartesian3.fromDegrees(116.389, 39.906, 150),
    cylinder: {
      length: 300, topRadius: 0, bottomRadius: 46,
      material: Cesium.Color.fromCssColorString('#4d9bff').withAlpha(0.85),
      outline: true,
      outlineColor: Cesium.Color.fromCssColorString('#cfe4ff')
    },
    label: {
      text: '目标点',
      font: '500 12px "Microsoft YaHei", sans-serif',
      fillColor: Cesium.Color.WHITE,
      pixelOffset: new Cesium.Cartesian2(0, -12),
      disableDepthTestDistance: Number.POSITIVE_INFINITY
    }
  });

  /* 三个位姿：全球、城市、贴近地平线 */
  var POSES = [
    {
      destination: Cesium.Cartesian3.fromDegrees(105, 35, 9000000),
      orientation: { heading: 0, pitch: Cesium.Math.toRadians(-90), roll: 0 }
    },
    {
      destination: Cesium.Cartesian3.fromDegrees(116.376, 39.895, 1600),
      orientation: { heading: Cesium.Math.toRadians(30), pitch: Cesium.Math.toRadians(-28), roll: 0 }
    },
    {
      destination: Cesium.Cartesian3.fromDegrees(116.389, 39.902, 60),
      orientation: { heading: Cesium.Math.toRadians(0), pitch: Cesium.Math.toRadians(2), roll: 0 }
    }
  ];

  var buttons = [
    document.getElementById('p0'),
    document.getElementById('p1'),
    document.getElementById('p2')
  ];

  function select(i) {
    viewer.camera.setView(POSES[i]);
    buttons.forEach(function (b, k) { b.className = k === i ? 'on' : ''; });
    document.getElementById('p3').className = '';
  }

  buttons.forEach(function (b, i) {
    b.addEventListener('click', function () { select(i); });
  });

  /* lookAt：给出目标点、航向俯仰与距离，相机自动落在球面外 */
  document.getElementById('p3').addEventListener('click', function () {
    buttons.forEach(function (b) { b.className = ''; });
    this.className = 'on';
    viewer.camera.lookAt(
      TARGET,
      new Cesium.HeadingPitchRange(
        Cesium.Math.toRadians(35),
        Cesium.Math.toRadians(-18),
        900
      )
    );
    viewer.camera.lookAtTransform(Cesium.Matrix4.IDENTITY);
  });

  var camEl = document.getElementById('cam');
  var carto = new Cesium.Cartographic();

  scene.postRender.addEventListener(function () {
    Cesium.Cartographic.fromCartesian(viewer.camera.positionWC, undefined, carto);
    camEl.textContent = '高 ' + Math.round(carto.height) + ' 米 · 航向 ' +
      Math.round(Cesium.Math.toDegrees(viewer.camera.heading)) + '°';
  });

  select(0);
})();
</script>
</body>
</html>