216 lines
7.9 KiB
TypeScript
216 lines
7.9 KiB
TypeScript
import * as Cesium from 'cesium';
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import { type Viewer } from 'cesium';
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import { eciToEcf, gstime, propagate, twoline2satrec } from 'satellite.js';
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/**
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* 未来2小时内每30秒的位置
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*/
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export async function demo_02_Track(viewer: Viewer) {
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const tle = `STARLINK-11371 [DTC]
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1 62879U 25024A 25062.93300820 .00003305 00000+0 21841-4 0 9995
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2 62879 42.9977 257.3937 0001725 269.2925 90.7748 15.77864921 5143`;
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// 解析TLE数据
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const lines = tle.split('\n') as [string, string, string];
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const satelliteName = lines[0]?.trim();
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const satrec = twoline2satrec(lines[1], lines[2]);
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// 创建卫星实体
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const satelliteEntity = viewer.entities.add({
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id: 'STARLINK-11371',
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label: {
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fillColor: Cesium.Color.WHITE,
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font: '14pt sans-serif',
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outlineColor: Cesium.Color.BLACK,
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outlineWidth: 2,
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pixelOffset: new Cesium.Cartesian2(0, -10),
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style: Cesium.LabelStyle.FILL_AND_OUTLINE,
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text: satelliteName,
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verticalOrigin: Cesium.VerticalOrigin.BOTTOM,
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},
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name: 'STARLINK-11371',
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// 卫星轨迹
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path: {
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material: new Cesium.PolylineGlowMaterialProperty({
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color: Cesium.Color.BLUE,
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glowPower: 0.2,
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}),
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resolution: 1,
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width: 2,
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},
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// 使用简单点图形表示卫星
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point: {
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color: Cesium.Color.YELLOW,
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outlineColor: Cesium.Color.WHITE,
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outlineWidth: 2,
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pixelSize: 10,
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},
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});
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// 计算并绘制卫星轨迹
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const totalSeconds = 60 * 60 * 2; // 2小时的轨迹
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const timeStepInSeconds = 30; // 每30秒一个点
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const startTime = Cesium.JulianDate.fromDate(new Date());
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const endTime = Cesium.JulianDate.addSeconds(startTime, totalSeconds, new Cesium.JulianDate());
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// 设置时钟范围
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viewer.clock.startTime = startTime.clone();
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viewer.clock.stopTime = endTime.clone();
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viewer.clock.currentTime = startTime.clone();
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viewer.clock.clockRange = Cesium.ClockRange.LOOP_STOP;
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viewer.clock.multiplier = 30; // 30倍速播放
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// 设置时间轴范围
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viewer.timeline.zoomTo(startTime, endTime);
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// 用于存储卫星位置的样本集合
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const positionProperty = new Cesium.SampledPositionProperty();
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// 用于存储轨道点的数组（用于显示完整轨道）
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const orbitPositions: Cesium.Cartesian3[] = [];
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// 保存卫星高度数据，用于覆盖范围计算
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// const satelliteAltitude = 550_000; // 默认高度为550公里
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// 计算轨道上的点
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for (let i = 0; i <= totalSeconds; i += timeStepInSeconds) {
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const time = Cesium.JulianDate.addSeconds(startTime, i, new Cesium.JulianDate());
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const jsDate = Cesium.JulianDate.toDate(time);
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// 计算卫星位置
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const positionAndVelocity = propagate(satrec, jsDate);
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if (typeof positionAndVelocity.position === 'boolean') {
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console.error('Error calculating satellite position');
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} else {
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const gmst = gstime(jsDate);
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const position = eciToEcf(positionAndVelocity.position, gmst);
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// 转换为Cesium坐标（单位：米）
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const cesiumPosition = new Cesium.Cartesian3(position.x * 1000, position.y * 1000, position.z * 1000);
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// 计算卫星高度
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// const cartographic = Cesium.Cartographic.fromCartesian(cesiumPosition);
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// satelliteAltitude = cartographic.height;
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// 保存位置用于绘制完整轨道
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orbitPositions.push(cesiumPosition);
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// 添加位置样本
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positionProperty.addSample(time, cesiumPosition);
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}
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}
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// 添加完整轨道线
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viewer.entities.add({
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id: 'STARLINK-11371-orbit',
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name: 'STARLINK-11371 Full Orbit',
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polyline: {
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clampToGround: false,
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material: new Cesium.PolylineDashMaterialProperty({
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color: Cesium.Color.CYAN,
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dashLength: 8,
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}),
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positions: orbitPositions,
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width: 1,
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},
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});
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// 设置卫星的位置
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satelliteEntity.position = positionProperty;
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satelliteEntity.orientation = new Cesium.VelocityOrientationProperty(positionProperty);
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// 添加卫星覆盖范围
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// Starlink 卫星通常覆盖范围以锥形方式向地面投射
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// 创建一个椭球体来表示卫星的覆盖范围
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const coverageAngle = 45; // 覆盖角度（度）
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// satelliteAltitude * Math.tan(Cesium.Math.toRadians(coverageAngle));
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// 创建覆盖范围实体
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viewer.entities.add({
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ellipsoid: {
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material: Cesium.Color.BLUE.withAlpha(0.2),
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outline: true,
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outlineColor: Cesium.Color.BLUE.withAlpha(0.8),
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radii: new Cesium.CallbackProperty(() => {
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const position = satelliteEntity.position?.getValue(viewer.clock.currentTime);
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if (!position) return new Cesium.Cartesian3(10_000, 10_000, 10_000);
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// 获取当前卫星高度
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const cartographic = Cesium.Cartographic.fromCartesian(position);
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const height = cartographic.height;
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// 计算覆盖范围半径 (基于锥角)
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const coverageRadius = height * Math.tan(Cesium.Math.toRadians(coverageAngle));
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// 椭球体形状: xy平面为圆形基底，z轴方向为高度
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return new Cesium.Cartesian3(coverageRadius, coverageRadius, height / 2);
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}, false),
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slicePartitions: 24,
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stackPartitions: 16,
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},
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id: 'STARLINK-11371-coverage',
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name: 'STARLINK-11371 Coverage',
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orientation: new Cesium.CallbackProperty(() => {
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// 确保椭球体始终指向地球中心
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const position = satelliteEntity.position?.getValue(viewer.clock.currentTime);
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if (!position) return Cesium.Transforms.eastNorthUpToFixedFrame(new Cesium.Cartesian3());
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// 计算从卫星到地球中心的方向
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Cesium.Cartesian3.normalize(Cesium.Cartesian3.negate(position, new Cesium.Cartesian3()), new Cesium.Cartesian3());
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return Cesium.Transforms.headingPitchRollQuaternion(position, new Cesium.HeadingPitchRoll(0, Math.PI, 0));
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}, false),
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position: positionProperty,
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});
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// 添加地面覆盖范围投影
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viewer.entities.add({
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ellipse: {
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granularity: Cesium.Math.toRadians(1),
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height: 0,
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material: Cesium.Color.BLUE.withAlpha(0.2),
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outline: true,
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outlineColor: Cesium.Color.BLUE.withAlpha(0.8),
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outlineWidth: 2,
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semiMajorAxis: new Cesium.CallbackProperty(() => {
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const satPosition = satelliteEntity.position?.getValue(viewer.clock.currentTime);
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if (!satPosition) return 10_000;
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// 计算卫星高度
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const cartographic = Cesium.Cartographic.fromCartesian(satPosition);
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// 根据高度和覆盖角度计算地面覆盖半径
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return cartographic.height * Math.tan(Cesium.Math.toRadians(coverageAngle));
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}, false),
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semiMinorAxis: new Cesium.CallbackProperty(() => {
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const satPosition = satelliteEntity.position?.getValue(viewer.clock.currentTime);
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if (!satPosition) return 10_000;
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// 计算卫星高度
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const cartographic = Cesium.Cartographic.fromCartesian(satPosition);
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// 根据高度和覆盖角度计算地面覆盖半径
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return cartographic.height * Math.tan(Cesium.Math.toRadians(coverageAngle));
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}, false),
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},
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id: 'STARLINK-11371-ground-coverage',
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name: 'STARLINK-11371 Ground Coverage',
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position: new Cesium.CallbackPositionProperty(() => {
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const satPosition = satelliteEntity.position?.getValue(viewer.clock.currentTime);
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if (!satPosition) return new Cesium.Cartesian3();
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// 计算卫星在地表的投影点
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const cartographic = Cesium.Cartographic.fromCartesian(satPosition);
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return Cesium.Cartesian3.fromRadians(cartographic.longitude, cartographic.latitude, 0);
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}, false),
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});
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// - https://community.cesium.com/t/entity-viewfrom-property-example/2299/3
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// - https://github.com/CesiumGS/cesium/issues/8900#issuecomment-638114149
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// - which is normal from a bird's eye view. But after setting it as the trackedEntity, it behaves abnormally.
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// 设置相机自动跟踪卫星
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viewer.trackedEntity = satelliteEntity;
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// 开始动画
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viewer.clock.shouldAnimate = true;
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}
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