Getting an odd artifact when source length is used in 4.12 Preview
Have to admit, this looks just amazing!
Hi Kneebasher,
This is a known issue that has been reported with UE-29543. Thank you for the report!
Tim
And still it is in 4.12.0 release…
BTW it is only visible with Use Inverse Squared Falloff - enabled.
Yep noticed that 
Hopefully it’ll be patched in in 4.12.1 or so… Unfortunately I lose the effect I am going for when I disable Inverse Squared Falloff and reduce the brightness, plus it makes some weird sparkles (like a photo flash) on some of my masked metallic materials. I’ll just have to wait till they figure it out.
Thanks though 
Unfortunately this will not be fixed in 4.12. since it’ll invalidate the DDC. This will be resolved once 4.13 release.
You can follow the steps here to fix this yourself. It doesn’t require any source code changes or recompiling of the engine with Visual Studio. You just need to adjust a single line in the .usf file and it will recompile the shaders for the engine.
I hope this helps until it’s fixed in the next major release.
Tim
Thank You! Works like a charm.
Why this can’t be fixed in 4.12 patch? Rebuilding DDC isn’t a big deal IMO.
Thank You Tim! That typo has been wrecking some of my stuff since 4.11 was released, your fix worked perfectly.
And thank you S-ed for stirring the pot a little after the 4.12 patch, otherwise I might not have a solution now
Unfortunately, not all things that have been fixed internally will be pushed to the hotfixes. The decision was made to not include this one and since this one has a fairly easy workaround that the user can fix it’s been decided to wait until 4.13 for the fix to be integrated. Sorry for any inconvenience it may cause.
This was re-evaluated and the fix for UE-29543 was included in today’s 4.12.2 Hotfix. This will require shaders on all projects to be recompiled.
Cheers