I have run into this problem many times before, but I’ve just tried to avoid it. Now I’m doing a project where the issue is affecting the main focus of my film: a small paper boat.
There is an issue with directional lights in UE5, where it is blocked and casts shadows properly with static meshes, landscapes, and other objects, but when a Single Layer Water material is used, as in this project with Fluid Flux, the sun is reflected with no occlusion whatsoever.
This makes for bright highlights and reflections on the dark sides of objects, as well as completely lighting up (unrealistically) the unlit side of my paper boat because there are highlights on the water from the incorrect reflections.
Anyone know of ANY way to make Single Layer Water behave correctly with directional lights?!
Also, any way to make Lumen stop lighting up the dark sides of objects just because there is a reflection on that side? It’s treating the appearance of a reflection as a light source going away from the camera because of screen traces. But if I turn off screen traces, other things look worse. I’m new at this, so maybe there’s a simple solution ya’ll know about already.
Specular occlusion doesn’t appear to work on certain materials when using ray traced shadows. Perhaps there is a CVAR to fix it, but the easiest thing is to simply switch to virtual shadow maps for your sun instead of ray traced shadows.
I’m having this same issue in my project. Disabling ray-traced shadows for the sun fixes the issue with the water, but causes light-leaking everywhere else in the world (I have a lot of interior spaces).
Is this a limitation of the thin water shader or just a bug? There doesn’t seem to be another way to simulate the surface of water effectively. A transparent plane doesn’t show objects in its reflections, for example.
But virtual shadows do not have proper area shadows. Even the sun, or a directional light can and should cast blurry shadows in certain conditions. Like when the objects are quite far from the ground. Like leaves of a tall tree.
For now only RT shadows can do that. Proper mixing of sharp shadows from close to the ground objects with soft shadows.
in a static level without day/night cycle you can to some degree cheese it, rather cheap. means… if you don’t rely on athmosphere and your horizon is covered.
you just gotta sync your visible skybox and a “custom” aka baked skylight hdri for the sun/sky reflection. just put the specular scale to 0, so… the directional will not contribute to water or any reflections. the whole sky reflection is replaced by the hdri. the visible sky can have any effect, but it will not show up in the reflections. it doesn’t do that either way, as i have set up my test level.
you just gotta bake a skybox for the desired light position in the sky in the level and maybe some clouds. the whole thing requires epic settings, afaik. unless you wanna customize it for your case.
thing on the right is a glass panel, btw. it can totally reflect anything.
