How to generate featureId in gltf

in this example,every geometry have a featureId,how they are generated?

i read the document below and still don’t know how to use featureIdAttribute.schema.json

i notice the sample FeatureIdAttribute.gltf show it come from GitHub - javagl/JglTF: Java libraries related to glTF, but i can’t find the entrance to run the code


@sean_lilley can you give me some advice

also,i want to generate some geometry like sandcastle show for test,can you give me more information or detail document

@ptrgags @sanjeetsuhag @patrick can you give me some advice