Storing normal map X, Y in UV for further use in Unreal Engine

Sup guys :slight_smile:

Im trying to wrap my head around that idea:
We store X and Y in U and V simply by placing vertices where we need.
After we append them and use DeriveNormalZ (reference: DeriveNormalZ and Compression Artifacts in Materials and Textures - YouTube)

Why i even try to do this? Because i cant work with custom split normal data, and baking any normal maps are absolutely not an option.
And only thing which i need is smooth normal transition between premaded geometry.

My problem is that im not that familiar with such cases and cant really get any valuable results.
I understand what normals should be by somehow thansform but cant really get - how exactly?

Maybe someone already try something like this?

Well, the answer was founded.
Simply because i dumb, i complitely ignore transformation from local to world space first, and only then, from world space to tangent space.
But debugging what VertexNormalWS are show me, i was able to find that mistake and get my normals (as best as it cant be taking into account that wierd methot to bring them to unreal :grimacing:)