超图平台cesium实现流动线

超图在cesium进行了二次开发，其中的流动线已经开发好了，可以拿过来直接使用

viewer.entities.add({
  // name:entity.name,
  polyline: {
    positions: Cesium.Cartesian3.fromDegreesArray([
      121.534575, 38.926131, 121.537579, 38.92543, 121.541784, 38.924578,
      121.543973, 38.924144, 121.545947, 38.923944,
    ]),
    width: 2,
    material: Cesium.Color.DARKORANGE.withAlpha(0.7),
    // clampToGround: true,
    // show: true,
  },
})

let polyLine = viewer.entities.add({
  // name:entity.name,
  polyline: {
    positions: Cesium.Cartesian3.fromDegreesArray([
      121.534575, 38.926131, 121.537579, 38.92543, 121.541784, 38.924578,
      121.543973, 38.924144, 121.545947, 38.923944,
    ]),
    width: 4, // 线的宽度，像素为单位
    material: new Cesium.PolylineTrailMaterialProperty({
      // 尾迹线材质
      color: Cesium.Color.GOLD,
      trailLength: 0.4,
      period: 3.0,
    }),
  },
})