I noticed a strange behavior - when I have a directional light in a scene, it always illuminates objects in the terrain layer, unless the culling mask is set to Nothing (or the light is turned off). But if only one layer is selected (that isn’t Terrain) it still lights up stuff on the Terrain layer.
If the Terrain layer is unselected from the mask, then shadows cast by objects on that layer dont’ show up, so the setting IS doing something. But it seems to be ignored as far as illumination goes, specifically for the Terrain layer
I’m looking for a solution to this issue too. Run into the exact same thing except using point lights.
Using Unity version 5.6.1f1. Trying to get a point light to only light up an object in a particular layer, but no matter what layer I isolate via culling, the terrain is always receiving light, regardless of what layer I put the terrain in.
Just ran into this as well, any solutions out there?
Edit: Not a fix, but I found a workaround. At least for me, if the terrain has a non-built-in layer (e.g. a user layer named Terrain), it was hit by all non-off lights regardless of the mask applied to the lights. But when I switched the terrain’s layer to a built-in layer like Default or Water, it works as intended and the light source’s culling mask determines what it actually lights up. Weird stuff, seems like a persistent Unity bug.