Is it possible to improve additive translucency in fog/fade?

[Gez]

Levels made for GZDoom typically abuse fog or fade effects. (A good recent example is Unloved.) A side effect is that sprites with additive translucency lose their vibrancy and brightness in such conditions.
Here's a couple of screenshots to illustrate what I mean.

Normal display:


With idbeholdl cheat to cancel the fog:


Without the fog, the fireball is bright and easy to see. With it, it loses its brightness and would probably be better off just being fullbright like in Doom.

So, would it be possible to tweak additive light in fog to give them their radiance back?

(Not a bug report or feature suggestion because at the moment I am more interested in an answer to the question than in an actual change in the code.)

[NeuralStunner]

Also note that even non-additive fullbright sprites are not actually fully bright in non-zero fog.

I have to ask: How are the fades made by Transfer_Heights done? They don't seem to have these problems. Also, I think 3D Floor interior fades ignore the sector fog altogether, much like sector light colors are ignored. (Which looks bad for gunflashes that light up part of the actual gun, but oh well...)

Also, I wouldn't say that Unloves really abuses colored fog... Just uses them a lot, and they happen to have issues.

Assuming this were possible to change, maybe a RespectFullBrights flag or some such would help? Since some users of fade colors (like Hexen!) are using it for actual fog, which realistically should obscure everything.

[Graf Zahl]

This just mimics the software renderer which can't mix fullbright with fog.

[Gez]

So, it would be possible to mix fullbright/additive light with fog, but it's not done so as to emulate the software renderer?

Would making it an option be reasonable?

[Gez]

I ended up making myself a hack to re-establish bright sprites and brightmaps in faded/foggy conditions. (On this screenshot, testcolor black has been used to exaggerate the contrast.)


De gustibus et coloribus, etc. Personally, I like it better that way.

[NeuralStunner]

Personally, I like it better that way.

As do I! Now we need a non-hacky way, so we can have a MapInfo option or some such for it.

[Gez]

APNG animation to compare with and without the hack:

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And the hack for anyone who wants it (and can compile GZDoom), using a new CVAR (gl_sprite_brightfog):

brightfoghack.zip