[Closed] FXAA without tonemapper
I would like to use FXAA without tonemapping. If I either replace the tonemapper with a custom one (as a blendable in a global post process volume), or disable it completely using FEngineShowFlags, FXAA does not seem to work anymore. Is this expected behaviour ?
Note : temporal AA still works in this case, but I would prefer FXAA since I am capturing a preview scene (previous frames information would not be available for TAA).
The question has been closed Oct 27 '16 at 09:20 PM by AndrewHurley for the following reason:
The question is answered, right answer was accepted
Hi Nicolas, Thanks for reporting this. It looks like this is a bug. FXAA requires luminance in the alpha channel in order to work, and that's not generated if you're using a custom tonemapper.
You could workaround (albeit with some loss of quality) by defining FXAA_GREEN_AS_LUMA 1 in FXAAShader.usf.
The proper fix would probably involve modifying the pixel shader in PostProcessMaterialShaders.usf like this (from PostProcessTonemap.usf):
You'd probably want to only do that for materials with BL_ReplacingTonemapper.
I think also you'd need to make the BL_ReplacingTonemapper PostProcessMaterial output to a R8G8B8A8 texture, because it uses an R11G11B10 buffer currently.
I'll get this bugged at our end so we fix it in a future release.
answered Oct 27 '16 at 09:19 PM
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