Per-pixel translucent lighting not using light falloff distance
I've recently started using the new per-pixel translucent lighting engine in 4.8, and I believe I've discovered a bug. It looks as though the specular reflections are not considering the falloff distance of point lights. In my scene I have a water plane, which, as you can see in the image, is reflecting a red light. The only red light in my scene (and I verified it was caused by this light by changing the colour) is more than 20,000 units above the surface of the water - but only has a 1000 unit falloff radius.
This is very inconvenient, as fine control over the range of lights is absolutely critical for my use case. Am I just doing something wrong, or is this a bug that needs fixing?
EDIT: After a bit more testing, it seems this bug only occurs if a light is given a source radius. If the light is left as a regular point light, it seems to work as expected.
I believe you will be interested in this post from the release notes.
As it is still flagged as experimental there are still some features that are not supported with this Lighting mode. This is from our 4.8 release notes and the light mode does not supported shadows within our latest version of UE4.
There are a couple of workarounds that include putting a plane with the same material set to Volumetric light mode.
Thanks for reporting this to us, however, this is expected behavior with the SurfacePerPixelLighting.
answered Dec 29 '15 at 08:16 PM
Interestingly, the problem seems to have arbitrarily solved itself. I'm not sure what the problem was originally, but I've just reset everything to how it was when I took that screenshot, and there's no red specular component on the water any more. How odd.
EDIT: I'll reopen this question if the problem reoccurs at any point.
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