Working in Unreal Engine 5.6 is a constant struggle for me, especially while using Forward Rendering. After mitigating many problems i didn’t had while working in Unity i’m facing this:
As you can see, directional light, while viewing at most angles, looking higher is removes this light and lower is increases to the point that wall is lit up too, passes through solid roof mesh 0.5m thick.
Also, when moving camera closer, light does this, i tried near clip setting and it does nothing.
Don’t want to use Deffered rendering because same scene (same custom material, player model, most basic movement/looking scripts) in Unity gives me 1500+ frames and Unreal only 400-500 with buggy shadows and 25-30% CPU usage on 5800X3D and while using RT on my RTX4080s it shows 90-110 frames without profiler in editor with 66% scaling and epic settings, didn’t had this problem on 4.26 a while back.
This reminds of another thread a few days ago, with a similar problem. Have you checked for gaps between your geometry? The light could be leaking from one. As well, the wall look a bit thin from the screenshots, I would add more thickness to the wall, and disable Two Sided materials for the ceiling. You can also test out using light channels in your directional lights, to affect specific sections of your building (channel 0 could affect the columns, channel 1 for the ceiling, and so on).
Everything is made in Blender, i’m using 0.125 grid scale, units are 1:1 to UE and everything is assembled as whole by using multiple meshes on import. Every wall, roof etc. is 0.5m thick, i tried increasing it, but to no avail, moving roof higher/lower doesn’t help either..
Only Dynamic Inset Shadow affect this bug, by eliminating this light leak (but it seems, that’s more like a some strange clipping, rather than a light leak) but presents me with new problem - there’s a light band on whole perimeter where roof mesh contacts other meshes..
I’m trying to diagnose what causing these visuals, rather than fix it immediatly and forget.
From what you describing, it further pushes the possibility of a gap between parts of your mesh, specially if coming from Blender, which has a history of shenanigans when working with Unreal.
Since the building is assembled from different meshes, I would test merging the assets on the sections were you are seeing light leaks.
Please make sure that all transforms are applied from Blender before exporting, as well as any active modifiers. Also, look for non-manifold geometry, check your face normals, and clean up your geo.
I know how to export from Blender to UE, i checked absolutely everything, i found some examples from other games with same level geometry, that were built on 4.26..
Not only on that wall this bug occurs, but outside is affected too!
It feels like some strange camera glitch, panning down with MMB removes more of the shadow on the outside, left to right is no change and rotating camera with RMB removes these visuals at some angles.
Alright, i stretched roof mesh little bit lower problem still persists. Dynamic Shadow Distance set to 25000 instead of default 40000 removes this light from most angles, setting back to 40000 and turning on Dynamic Inset Shadow removes light completely and without light band on wall meshes. Jesus, is it really necesarry to be this hard for such simple task?..
