I am interested in writing an add on tool that could read and write certain types of asset directly for inclusion in UE4 projects. Is there any formal file specification for this file format?
I was aiming at an external tool for browsing blueprints / Materials.
There isn’t a file format specification for .uassets. Rather, the format is defined by the ULinker code in the engine together with all of the various serialization routines for objects and datatypes.
To read and write .uasset files, use the UE4 code. If you want to write a command-line to that reads/writes .uasset files, see the UCommandlet interface (UCommandlet | Unreal Engine Documentation).
Thanks for the answer, so as I understand it:
.uasset is a generic extension for a collection of individual serialised asset types without an overarching file format.
So to use them, I would need to use the existing serialisation / de-serialisation code in the UE4 full source to access it.