This documentation describes light function atlas, a way to optimize rendering time of light using light function materials.
https://dev.epicgames.com/community/learning/tutorials/7JVy/unreal-engine-light-function-atlas
Seriously awesome work, I’m shocked this wasn’t highlighted in the release notes for 5.4, I had no idea this was even added til I spotted this tutorial on the learning hub.
I was hoping you could elaborate on what you mean by this statement?
UVs should not be manipulated in order to sample a texture. Or the UV manipulation has to be aligned to the texture space edges of the light function. Otherwise, the atlas slot will not be repeatable.
I did some quick tests with panning/rotating coordinates and they all worked fine. I’m not sure what kind of sampling would produce issues (and what those may be?)
Also noticed that Lumen’s surface cache only renders the red channel. I assume this is by design, just curious if there are any plans to add surface cache support for RGB light functions in the future:
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Thanks!
It was coming in hot for 5.4, unsure it would make it even. It will be highlighted in 5.5 officially.
The UV manipulation is a problem only for rect and dir lights which will tile the UV space in the world. And if the UV are not multiples of integer, the tiling will not work (texel missmatch at edges). Same if you use the tiling method on the light itself, that for all the light type I believe. I will clarify that in the documentation, good remark!
As for lumen, thanks for the bug report! I will fix it for 5.5.
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