Point light causes black void (Source length)

Increasing the source length of a point light regardless of the source radius causes this cool, but certainly odd “Black hole” effect.

Hi Sythen,

This has already been reported and has recently been fixed internally. Look for this to be resolved in 4.13

If you want to fix this yourself you can do so in the DeferredLightingCommon.usf file. This DOES NOT need to be recompiled or use a source build. This can be simply done on the Binary version if needed.

Located the .usf file in /Engine/Shaders/DeferredLightingCommon.usf

If you’re using Notepad ++ look for line 318 and change it to be

float Length1 = LengthSqr1 * rLength1;

There was a typo where it was looking at LenthSqr0 * rLength0 instead of length1.

Once you make the changes you can simply restart the editor and allow the shaders to recompile and it should work correctly now.

I hope this helps.


If the solution is “float Length1 = LengthSqr1 * rLength1;” can someone explain me why if is fixed in 4.12 Epic Games revert the fix before the 4.12.1 ? https://github.com/EpicGames/UnrealEngine/commit/20d6594777fc17a949db34f2bf439a52aa102fbd to wait until the 4.13 ?

The fix in 4.12 in 2998541, but pulled back out in 2999636 because it would cause the DDC to be invalidated. Since we did not want that to happen it has been decided to push the fix in 4.13. You can easily fix the issue using the above steps.

Thank you Tim, the above fix works wonders! :slight_smile: