gltf v2

[MaikKlein]

I have seen that you have started to support v2 in the incoming branch. Would you say that it is already in a usable state?

[alteous]

It's certainly usable if you just want to deserialise .gltf files. I plan to merge this code when the official 2.0 specification is released. Until then the data structures are subject to change as the specification is finalised.

There are a few upcoming changes that you should prepare for however:

• All data structures in v2 are to be moved into a sub module v2::raw to make way for the upcoming wrapper interface.
• The Extras trait will be removed in favour of untyped serde_json::Values.

[alteous]

Also, I forgot to mention, the Get and TryGet traits will probably be removed.