Transluscent surface insanely bright after building lighting.

I have a simple plane that has a broken window texture across it, and uses a translucent material. The problem I have, is when I build the lighting, these surfaces are insanely bright compared to their surroundings.

I have light mass coordinates set-up on the place (it’s part of a larger surrounding mesh as well), and also have two-sided lighting and two-sided material checked in the material editor/details panel. Do translucent surfaces not have lightmass textures baked over the top of them? The issue was never present in UE3, which applied shadowing just like a multiply layer on top as far as I know.

The material network is pretty simple. I also tried creating a two-sided plane in 3DS Max with separate lightmass UV’s, but still to no avail. I did just find this on the UE4 Documentation though, but I am using stationary lights.

So… any clues?

Yes, I am afraid that static shadows currently do not affect translucency. Trust me us in house developers bring up this issue often :slight_smile: I know it is “planned” but I cannot say how much longer it might be since I don’t know.

For now, I can tell you that it is possible to capture the lighting manually and apply it manually as a texture inside the material. I have had to do it a few times. Basically you set the material to be a white opaque material and then rebuild, take a lighting only screenshot and import that with sRGB unchecked. If its a mesh more complex than a simple window pane, you can actually unwrap a mesh usinga vertex shader by using an unwrap material function. There is one somewhere in engine. 4.3 will have a BP powered tool for unwraping meshes so that you can do custom baking operations more easily.

If the lighting on the mesh is fairly flat, I would just correct for it using a material instance. Sorry I know that is probably not the suggestion you were hoping for.

Ah I had a feeling that might be the case… that’ll have to be the current workaround then!

There is one case where this actually works, in the ES2 mobile rendering preview you can actually see correct lightmaps on simple translucency.

The mystery deepens!