As a long time Blender user, I have always been impressed with the babylon exporter created by @JCPalmer - his patience and persistence in getting it right. One of the features I was impressed with (pre-Blender 2.80) was the ability to assign lights to objects in specific layer and only that layer. by simply checking a box that said “this layer only”.The code generated by the exporter would then contain a parameter for the light like this for a simple street light:
“includedOnlyMeshesIds”:[“mitre_street.”,“mitre_door1”,“mitre_house_walls”,“mitre_pavement”,“mitre_walls1”,“mitre_windows1”]
But with Blender 2.8 layers were replaced by “Collections”, and while different lights can be assigned to different collections, I can find no equivalent to simply check a box that says" this collection only"
An example where I have found it useful - a house with 6 rooms each with its own light or a lighted street area where lights only illuminated parts of a neighbourhood.
Or have I missed something ?
cheers, gryff 
