I’m trying to achieve an outline over objects, but using a much computationally cheaper method than post-processing (I already have a post-processing outline shader). In Unity, I’d just do a two pass shader, in the first pass, just scale the vertices along their normals, flip them, and then color the result a matte black. In Unreal, it doesn’t seem to be nearly so straightforward. I already have a nice toon shader going, but this specific thing seems to be eluding me. I’ve messed around with WorldPositionOffset and layered materials, but I’m honestly just flailing around trying to figure it out. Any general directions to toss me in?
There’s no way to access the geometry shader in the Material Editor. Sorry 
two pass = duplicate mesh and make sure you keep them in sync. Not ideal but it does work.