基于Cesium实现卫星在轨绕行动画

timeline: true, //是否显示时间线控件

    viewer = new Cesium.Viewer('map', {
      baseLayerPicker: false,  // 影像切换
      animation: true,  //是否显示动画控件
      infoBox: false, //是否显示点击要素之后显示的信息
      geocoder: false, //是否显示地名查找控件
      timeline: true, //是否显示时间线控件
      fullscreenButton: false,
      shouldAnimate: false,
      navigationHelpButton: false, //是否显示帮助信息控件
      terrainProvider: new Cesium.createWorldTerrain({
        requestWaterMask: true,
        requestVertexNORMals: true
      }),
      imageryProvider: new Cesium.UrlTemplateImageryProvider({
        url: "Http://mt1.Google.cn/vt/lyrs=s&hl=zh-CN&x={x}&y={y}&z={z}&s=Gali"
      })
    })

  // 卫星
  function satellite() {
    start = new Cesium.JulianDate.fromDate(new Date());  // 获取当前时间 这不是国内的时间
    start = Cesium.JulianDate.addHours(start, 8, new Cesium.JulianDate());  // 添加八小时，得到我们东八区的北京时间
    stop = Cesium.JulianDate.addSeconds(start, 360, new Cesium.JulianDate());  // 设置一个结束时间，意思是360秒之后时间结束

     
    viewer.clock.startTime = start.clone();   // 给cesium时间轴设置开始的时间，也就是上边的东八区时间
    viewer.clock.stopTime = stop.clone();     // 设置cesium时间轴设置结束的时间
    viewer.clock.currentTime = start.clone(); // 设置cesium时间轴设置当前的时间
    viewer.clock.clockRange = Cesium.ClockRange.LOOP_STOP;  // 时间结束了，再继续重复来一遍
    //时间变化来控制速度 // 时间速率，数字越大时间过的越快
    viewer.clock.multiplier = 2;
    //给时间线设置边界
    viewer.timeline.zoomTo(start, stop);

    rrStates = [];
    getRandState(arrStates, 1);
    startFunc();
  }

function mySatePosition() {
    this.lon = 0;
    this.lat = 0;
    this.hei = 700000;          //卫星高度
    this.phei = 700000 / 2;     //轨道高度
    this.time = 0;
  }

  function computeCirclularFlight(source, panduan) {
    var property = new Cesium.SampledPositionProperty();
    if (panduan == 1) {         //卫星位置
      for (var i = 0; i < source.length; i++) {
        var time = Cesium.JulianDate.addSeconds(start, source[i].time, new Cesium.JulianDate);
        var position = Cesium.Cartesian3.fromDegrees(source[i].lon, source[i].lat, source[i].hei);
        // 添加位置，和时间对应
        property.addSample(time, position);
      }
    } else if (panduan == 2) {//轨道位置
      for (var i = 0; i < source.length; i++) {
        var time = Cesium.JulianDate.addSeconds(start, source[i].time, new Cesium.JulianDate);
        var position = Cesium.Cartesian3.fromDegrees(source[i].lon, source[i].lat, source[i].phei);
        // 添加位置，和时间对应
        property.addSample(time, position);
      }
    }
    return property;
  }

  function getRandState(brr, count) {
    for (var m = 0; m < count; m++) {
      var arr = [];
      var t1 = Math.floor(Math.random() * 360);
      var t2 = Math.floor(Math.random() * 360);
      for (var i = t1; i <= 360 + t1; i += 30) {
        var aaa = new mySatePosition();
        aaa.lon = t2;
        aaa.lat = i;
        aaa.time = i - t1;
        arr.push(aaa);
      }
      brr.push(arr);
    }
  }

  function getStatePath(aaa) {
    var entity_ty1p = computeCirclularFlight(aaa, 2);
    var entity_ty1 = viewer.entities.add({
      availability: new Cesium.TimeIntervalCollection([new Cesium.TimeInterval({
        start: start,
        stop: stop
      })]),
      position: entity_ty1p,   //轨道高度
      orientation: new Cesium.VelocityOrientationProperty(entity_ty1p),
      cylinder: {
        HeightReference: Cesium.HeightReference.CLAMP_TO_GROUND,
        length: 700000,
        topRadius: 0,
        bottomRadius: 900000 / 2,
        // material: Cesium.Color.RED.withAlpha(.4),
        // outline: !0,
        numberOfVerticalLines: 0,
        // outlineColor: Cesium.Color.RED.withAlpha(.8),
        material: Cesium.Color.fromBytes(35, 170, 242, 80)
      },
    });

    entity_ty1.position.setInterpolationOptions({
      interpolationDegree: 5,
      interpolationAlgorithm: Cesium.LagrangePolynomialApproximation
    });

    var entity1p = computeCirclularFlight(aaa, 1);
    //创建实体
    var entity1 = viewer.entities.add({
      // 将实体availability设置为与模拟时间相同的时间间隔。
      availability: new Cesium.TimeIntervalCollection([new Cesium.TimeInterval({
        start: start,
        stop: stop
      })]),
      position: entity1p,//计算实体位置属性
      //基于位置移动自动计算方向.
      orientation: new Cesium.VelocityOrientationProperty(entity1p),
      //加载飞机模型
      model: {
        uri: './models/weixing/scene.gltf',
        scale: 1000
      },
      //路径
      path: {
        resolution: 1,
        material: new Cesium.PolylineGlowMaterialProperty({
          glowPower: 0.1,
          color: Cesium.Color.PINK
        }),
        width: 5
      }
    });

    //差值器
    entity1.position.setInterpolationOptions({
      interpolationDegree: 5,
      interpolationAlgorithm: Cesium.LagrangePolynomialApproximation
    });
  }

  function startFunc() {
    for (var i = 0; i < arrStates.length; i++) {
      getStatePath(arrStates[i]);
    }
  }