how to export the Entitty to one gltf file

Many questions are below

1 For example, I draw one Enitity in web explore in cesiumJs and after that I want to export the Entitty to one gltf file. (I need simple sample that describe how to do and so I can catch key point )
2 If I create one gltf in memory in Js client , How can I load it .
The problem is memory load. (cesiumjs is file loading and Now it is memory loading)
3 How to separate different Object in the same gltf file?
var model = scene.primitives.add(Cesium.Model.fromGltf({
url : ‘SampleData/models/CesiumGround/Cesium_Ground.gltf’,
In this way, you make the whole gltf as one Entity, Now I think if this gltf file has 2 real Entity,
whether can we handle with it (we can’t always make one gltf as one Entity)

Hello,

This kind of functionality is not something that is built into Cesium. You would have to write your own glTF export.

Take a look at our build guide for information on cloning and building the source code: https://github.com/AnalyticalGraphicsInc/cesium/tree/master/Documentation/Contributors/BuildGuide

Best,

Hannah