color bugs

ant1991331 · Post by **ant1991331** » Sun Jun 26, 2005 9:39 pm

i am having problems with color here, when you walk away from something purple it comes out grey, is there a way i can stop this?

Post by **Kirby** » Sun Jun 26, 2005 10:38 pm

Purple? Such as a custom texture or sprite? (As far as I know, there is no purple in the Doom resources) If so, it probably wont come out correctly because Doom's pallette can't handle blue colors correctly

Arcane · Post by **Arcane** » Mon Jun 27, 2005 12:38 am

It's Doom's lighting engine, I think.

For example, look at Romero's head from a distance and then get close.

ant1991331 · Post by **ant1991331** » Mon Jun 27, 2005 1:28 am

its funny how doom legacy dosent do that...

Arcane · Post by **Arcane** » Mon Jun 27, 2005 1:34 am

Well, being as how it was in the original engine, it's funny how Legacy doesn't work.

Post by **Graf Zahl** » Mon Jun 27, 2005 1:55 am

Legacy in software mode shows the same problems (not surprisingly!) Only in OpenGL mode with True Color it does not. As (probably not) everybody knows, ZDoom is software rendering only.

Post by **TheDarkArchon** » Mon Jun 27, 2005 7:31 am

Kirby wrote:Purple? Such as a custom texture or sprite? (As far as I know, there is no purple in the Doom resources)

Of course Id used purple, else it wouldn't be in the palette: However, the only cases of purple are the Nazi (On the firing frame at his crotch) and the Cacodemon's ball (Outer rim).

Cutmanmike · Post by **Cutmanmike** » Mon Jun 27, 2005 7:51 am

On the firing frame at his crotch

Why ID WHY!!

Arcane · Post by **Arcane** » Mon Jun 27, 2005 7:59 am

It's STILL not a problem.

It's LIGHTING.

Light-Amp gets rid of this, and so do bright lights. So I'm assuming it's lighting.

Post by **Enjay** » Mon Jun 27, 2005 8:44 am

cutmanmike wrote:Why ID WHY!!

Dunno, but I'm pretty sure it's there on the original Wolfenstein sprites too.

Arcane wrote:It's STILL not a problem.

It's LIGHTING.

Light-Amp gets rid of this, and so do bright lights. So I'm assuming it's lighting.

Yeah, it's lighting. I'm not sure exactly how it works, but I think what basically happens is that colours are mapped to other colours in the palette depending on how visible they are. So, in a dull room, as you walk away from a coloured wall, it gets displayed using progressively darker colours from the palette. I'm pretty sure that's one of the main functions of the colormap lump - it maps colours to other palette indices for different lighting/visibility conditions. Whether Zdoom actually still uses the colormap for that I'm not sure - I know some of the colormap functions are now done on the fly by Zdoom.

Anyway, with a colour like purple, where there are very few purple colours in the palette, as you move away from the wall (or whatever) it has to be mapped to something else to make it appear darker. If there is no suitable darker purple, it will be mapped to another colour that gives the closest possible match from the colours available in the Doom palette.

As has been said, this is not an issue with opengl because the port is no longer restricted to only the Doom palette colours.

Another good example of limited colour mapping is to set a room to have a pale-ish blue lighting effect, then go and view it in Zdoom versus ZdoomGL. In Zdoom, loads of things will appear grey with occasional patches of too bright blue. In ZdoomGL it will all appear a nice blue colour.

Post by **Graf Zahl** » Mon Jun 27, 2005 8:44 am

cutmanmike wrote:
On the firing frame at his crotch
Why ID WHY!!

Palette conversion error...

Phobus · Post by **Phobus** » Mon Jun 27, 2005 10:09 am

I know that colours are redone as you move away from them in low light levels (say 128, for the sake of my example). I've seen this sort of change (though not quite as drastic, or obvious) many a time both playing and making, so it's not really an error.

LK873 · Post by **LK873** » Mon Jun 27, 2005 11:25 am

That's what I love about GL ports, none-a that light mess-up stuff.

Killo Zapit · Post by **Killo Zapit** » Mon Jun 27, 2005 8:21 pm

If you wanted, you could just replace the COLORMAP with one that avoids that kind of thing. Say one that is calculated so each color gradient will only fade into colors of it's own gradient. It's entirely possible to make a colormap that helps this, though it won't be perfect by any means.

ant1991331 · Post by **ant1991331** » Wed Jun 29, 2005 2:58 am

eg. the Heretic colormap?