I have a female character with long dress and long hair meshes that are made of planes facing both directions but, the lightning of those areas have some issues (high contrast, looks like harsh normals). I could try using double sided planes for her hair (although I couldn’t find how to do that on just one part of a skeletal mesh, only on a static mesh) but this wouldn’t work for her dress that have different textures on the inside and the outside.
I don’t think the issue is with my textures since the parts of her dress on the torso and her hair bangs don’t need this backfacing and have no issues even though use the same material. I think it’s some option for material rendering that I’m missing.
Sorry if this has been answered already, I looked around and found similar questions but with solutions that didn’t solved my problem.
Thanks for the answer but I managed to get it working.
I tried setting up with the two sided sign but I couldn’t make it work for my mesh because I needed a specific different uv for the backside.
Just in case someone has the same issue I think it was actually a bug that was already fixed on latest versions of UE4. Here’s how it went: I had version 4.16.3 installed and started importing my mesh there to see what it would look like on engine and got this issue, later I downloaded some paragon characters to see if they had similar geometry somewhere (two planes to make double sided different textures, btw couldn’t find anything like it) and for them to work I needed a newer version of the engine. I downloaded 4.21.1, updated my project and the issue persisted, then today I imported a new version of the model and it was working as it should, I got confused for a while then reimported the original still bugged one and it magically worked as well. I made some more tests on the 4.16 project and it works fine for static meshes but not for skeletal meshes, so I think the newer version of the engine just can handle overlapping geometry facing different directions better.