I want to know how to judge the point on the back of the sphere.

CesiumJS
1

1. A concise explanation of the problem you're experiencing.

2. A minimal code example. If you've found a bug, this helps us reproduce and repair it.

3. Context. Why do you need to do this? We might know a better way to accomplish your goal.

4. The Cesium version you're using, your operating system and browser.

2

Not very good at English, all rely on google, thank you for your help

3

var projectedPoint = new Cesium.Cartesian3.fromDegrees(lon, lat, 0);
    var trans = Cesium.SceneTransforms.wgs84ToWindowCoordinates(mapApp.cesMap.scene_, projectedPoint);
    var ray = mapApp.cesMap.camera_.cam_.getPickRay(trans);
    var position = mapApp.cesMap.globe_.pick(ray, mapApp.cesMap.scene_);
    if (Cesium.defined(position)) {
        var cartographic = Cesium.Ellipsoid.WGS84.cartesianToCartographic(position);
        var lat2 = Cesium.Math.toDegrees(cartographic.latitude);
        var lon2 = Cesium.Math.toDegrees(cartographic.longitude);
//juge lat , lat2 lon,lon2
//low efficiency!!!!!!!!!
    }

4

Can you explain more what you’re trying to do? What kind of application are you working on?