Handles FBX documents. The FBXDocument handles FBX documents. It provides methods to append data from buffers or files, generate scenes, and register/unregister document extensions. When exporting FBX from Blender, use the "FBX Units Scale" option. The "FBX Units Scale" option sets the correct scale factor and avoids manual adjustments when re-importing into Blender, such as through glTF export.