In a nutshell, the glTF module works like this:
structures/
folder contains glTF structures, the
small pieces that make up a glTF file, represented as C++ classes.extensions/
folder contains glTF extensions, which
are optional features that build on top of the base glTF spec.GLTFState
holds collections of structures and extensions.GLTFDocument
operates on GLTFState and its elements.editor/
folder uses GLTFDocument to import and export 3D models.