The title is the question I have. The property name is vague as to how it affects lighting, or what lighting exactly it affects. I am studying Distance Field and I find them fascinating, but I don’t know exactly how they affect or impact lighting in a scene.
What I do see is that the character and the tank both have this option enabled in both pics. But the level itself has it turned off in the first and turned on in the second. In the second, the character has a square area around it that when the tank is in, the part of the tank that is in the square area becomes way too dark.
BTW, my GPU is old, but still smokes for the games I like to play: GTX 770 w/ DX11.
Notice in this second pic the back of the tank is outside the square area and is not darkened by the character. Also notice the darkened lines on the ground running forward and lateral from the tank. Those are simply on the ground when the level has its option Affect Distance Field Lighting enabled. And, like the square area around the character, they also darken the tank when the tank crosses over them, and the darkness is only as wide as those lines.
It basically determines whether or not the mesh will be added to the distance field representation of the scene, if it is disabled then it will not be represented in the Lumen scene (but will still be picked up by screen traces)
It’s also used for other features like distance field ao, SDF particle collision, distance field shadows, indirect distance field shadows… maybe other things. The mesh won’t affect any of those if “affect distance field lighting” is disabled.
Hard to know whats going on with your scene but this looks like a self-shadowing artifact from distance field AO. Distance fields can’t deform and they don’t respect vertex animation so this kind of issue is common on meshes that use WPO.
