// function drawLine(leftPoint, secPoint, color) {
// viewer.entities.add({
// polyline: {
// positions: [leftPoint, secPoint],
// arcType: Cesium.ArcType.NONE,
// width: 5,
// material: color,
// depthFailMaterial: color
// }
// })
// }
// pickFromRay.call(this);
// function pickFromRay() {
// for (var i = 0; i < destPoints.length; i++) {
// // 计算射线的方向,目标点left 视域点right
// var direction = Cesium.Cartesian3.normalize(Cesium.Cartesian3.subtract(destPoints[i], positions[0], new Cesium.Cartesian3()), new Cesium.Cartesian3());
// console.log(direction);
// // 建立射线
// var ray = new Cesium.Ray(positions[0], direction);
// var result = viewer.scene.pickFromRay(ray, objectsToExclude); // 计算交互点,返回第一个