What i tried was to separate the mask of the material. mask out the blue channel of the normal and then multiply that with the material normal to create a defined edge normal where the 2 or 3 materials overlap.
But this does not seem to work.
Your options are World Position Offset, Normal Maps, Bump Offset, POM, Tessellation. Those are roughly in order from cheapest to most expensive.
World position offset can offset vertexes on a mesh, but it requires there to be enough vertexes to add the detail you want. It’s great for vertex blending in sand and snow where you want it to pile up, and can be used for wind effects and a bunch of different uses.
It looks like you already have normal maps, but some larger details in it can add more depth.
Bump offset adds depth based off camera position, often used for bricks in game, it was notably used in The Elder Scrolls IV: Oblivion. There are some artifacts and swimming with the texture.
POM is a more advanced bump offset and it can effect the silhouette of a mesh. I wouldn’t blend multiple layers of POM together, but you could vertex paint moss onto rocks that use POM.
Tessellation. Expensive and a pain to mess with, but it works on meshes where POM wouldn’t
Experimented with the above.
My main challenge is / was that my mask comes from a material function. So i cannot use any of the cool functions like heightmap to normal.
POM gave terrible artifacts.
I eventually settled to tackle this way later down the line once i stumble across a propper cheap solution. I noticed Epics stuff didnt address this in UT4 so i so no need to go so advanced.
At least i learned a lot during the investigations.
I settled on a simple 3 layer vertex blend with a master normal.
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