when we provide a add_simulation_data to Vframe class instance, we provide a filename, where numerical data is stored ..
We can give that filename to the JSON..
It would be containing the stuff limited to that VFRame ..
for example ..
on calling vframe.generate_json() ...
we get something like ...

[vframe1: {name: ..., shape: ... , shape_related_numerics: ..., simulation_data: /filename.json , tranform_matrix:[ [],[],[]] ..]

and when we call 
Scene.gen_json ..
it recursively calls on all vframes which are children of Scene, and take all those json objects,and compile them into one ..

[Scene1:{width:800,heigth:800, ...
              vframes: { vfame1:data_got_from_vframe1.gen_json, vframe2:data_got_from_vframe2.gen_json ... }}]