Things about Doom you just found out

[scifista42]

3 things about Doom I've just found out:

1. This wall in Doom2 MAP08 is lower-unpegged. When the staircase for demons raises, you can notice how the entire wall goes up.

2. This blood pool in Doom2 MAP25 is damaging on the periphery, but the top of the revenant's pillar (actually a descendable lift when you press it) is non-damaging, despite also consisting of blood.

3. If you use "freeze" cheat in ZDoom to halt movement of all things, and then use it again to unfreeze things back to normal, Revenant's missiles (those currently in the air) might change their status of being homing or not - either they will stop tracing their target even if they previously did, or vice versa. It's because their A_Tracer function only works in odd tics, which I knew, it just never occured to me that the "freeze" command would have such an interesting effect on them.

[joe-ilya]

SavageCorona said:

WHO WOULDA THUNK IT?????

Please read the whole replie instead of pulling a sentence from a paragraph.

[VGamingJunkie]

I didn't realize this until I read the wiki since I had never played Doom II for GBA but the spectres appear to have an effect that refracts everything behind them. That's pretty impressive for GBA standards, the only source port of Doom I know of that has anything similar is the refracted reflections in the liquids in DoomGLES.

[Marnetmar]

<snip, wrong thread>

[Linguica]

MetroidJunkie said:

I didn't realize this until I read the wiki since I had never played Doom II for GBA but the spectres appear to have an effect that refracts everything behind them. That's pretty impressive for GBA standards, the only source port of Doom I know of that has anything similar is the refracted reflections in the liquids in DoomGLES.

Actually the refraction effect has been present since the original Doom, but it's always been very difficult to notice: https://www.doomworld.com/vb/post/1335541

[VGamingJunkie]

So the effect in the GBA version of Doom 2 was what ID was originally going for with the spectre but botched it due to the effect darkening the shifted pixels? It's certainly much more noticeable in the GBA version, at least, maybe because it's of a lower resolution.

http://v8.tinypic.com/player.swf?file=nw08ja&s=8

Only a shame this effect can't be replicated in GZDoom or some other OpenGL source port, it'd make a great pseudo refraction effect since none seem to exist outside the aforementioned DoomGLES.

[RestlessRodent]

MetroidJunkie said:

Only a shame this effect can't be replicated in GZDoom or some other OpenGL source port, it'd make a great pseudo refraction effect since none seem to exist outside the aforementioned DoomGLES.

It can be replicated in any version of OpenGL, however this does not mean it will be fast.

[VGamingJunkie]

Fast as in the time it would take to implement or in how fast the method shifts the pixels around?

[SavageCorona]

joe-ilya said:

Please read the whole replie instead of pulling a sentence from a paragraph.

I did read it all but you still see my point, right?

[Alfonzo]

Typing IDBEHOLDS while dead in chocolate doom will alert monsters to your presence. They'll cycle through their walking animation without moving anywhere. Wowzer!

[fraggle]

Alfonzo said:

Typing IDBEHOLDS while dead in chocolate doom will alert monsters to your presence. They'll cycle through their walking animation without moving anywhere. Wowzer!

This is Vanilla behavior.

[VGamingJunkie]

Typing IDDQD while dead in Vanilla makes the status bar seem to be alive even though the player remains dead and monsters that can see the player are alerted. Kind of funny that the status bar is stuck in the angry face if you do. I guess I'd be upset too if I was stuck in limbo like that, thanks player. XD

[LigH]

GhostlyDeath said:

It can be replicated in any version of OpenGL, however this does not mean it will be fast.

It would probably be implemented best as pixel shader effect...

[VGamingJunkie]

GZDoom has a texture warping effect, I wonder if that could be tweaked to warp surfaces behind it.

[Antroid]

I just found out that the doom 2 map I always remembered as "Tenements" is actually "The inmost dens" and vice versa. What the hell.

[Avoozl]

For some reason I have remembered The Spirit World as being named The Living End.

[Antroid]

Now that's just silly.

[Maes]

MetroidJunkie said:

GBA refraction effect

It looks just like the one in vanilla Doom, only that it lightens pixels instead of darkening them. The higher the resolution however, the less impressive the effect is, and the more it starts looking like a wavy interference pattern instead.

To keep it looking as intended at higher-than-vanilla resolutions, it should be applied at an artificially lower resolution/increased blockiness, otherwise it looks completely wrong.

[VGamingJunkie]

Linguica already corrected me on that, I didn't know that the spectre effect was actually a "refraction" effect. It's kind of a missed opportunity on ID's part since the pixels are so dark that you wouldn't know the environment is being twisted behind them and such an effect would probably blow our minds back then.

[Avoozl]

The music track in Doom 2 titled "Waiting for Romero to Play" was originally in Doom 1 while John Romero showed off the game to a few ID members in the video A Visit to id Software (1993) and the very track was in E1M3 while he did that, so that's probably why it was titled "Waiting for Romero to Play" in the first place I would guess.

[Linguica]

I just noticed that Doom had a bug in its gamma correction code that has been carried over to most modern software Doom ports.

Doom never displays the palette directly, but instead first runs it through the gamma correction code before using the resulting palette values. To do its "gamma correction", Doom has an internal lookup table (LUT) for the 5 gamma levels. For each one it defines, given an input color level, what the final color level should be. So for instance, for a color with a red level of 64, it will look at the 64th value in the appropriate gamma level LUT, and return the value it finds.

The only problem is that the "normal" gamma level of 0 is slightly wrong for half the values. The component colors can (obviously) range in value from 0 to 255. However, the table goes from 1 to 255, with 128 being repeated twice in the middle of the range.

You can see this in a modern port like Eternity or PrBoom-plus (in software obv) - go to a dark place and take a printscreen, and then use the eyedropper tool to look at a "pitch black" area. On gamma 0, the darkest you will find is (1,1,1) instead of the expected (0,0,0).



This has been noted before, but I had never noticed.

[FireFish]

Linguica said:

Turns out when things don't fade into darkness in the distance the game looks a lot worse, who knew??

This reminds me of what happens when you yank the shadows out of DooM 3 and force it to be bright... ugly things, ugly things.

Never_Again said:

Simply amazing. That means you could disconnect all streetlights in Manhattan and hoist just one to the top of the Empire State building, The streets at night would be just as bright as with thousands of the current streetlights, but think of all the electricity this would save.

There just might be a Nobel Prize in this for you, Linguica.

Haha, nice one.

[Memfis]

"Light blinks" type sectors seem to blink in order from the highest numbered sector to the lowest numbered sector. Might be useful for arranging neat lighting effects.

[dobu gabu maru]

Memfis said:

"Light blinks" type sectors seem to blink in order from the highest numbered sector to the lowest numbered sector. Might be useful for arranging neat lighting effects.

Oh man I was trying to figure out the logic to this for a while! Glad to know that's how it works

[Linguica]

You could always look at the source code...

[Jaws In Space]

Not everyone knows what to look for when looking at the source code

[Doomkid]

SavageCorona said:

Mapping in Vanilla makes you realise how little vision they had when making their presets.

Well for a game with a sorta brief development time, it makes sense that there weren't as many as with Boom for example. And hey, I think all those built in lighting effects alone, show how much vision they had

joe-ilya said:

The engine roots between Ultimate doom and doom 2 are so close.
[..]
The lost souls in ultimate doom don't count as kills in the intermission screen even through ultimate doom countains no pain elementals, making ultimate doom(or the before doom2 game called "doom") predict pain elementals.

I think this was revised somewhere along the way, but maybe it has to do with that "wall lost soul spawner" that Romero posted about in that thread of goodies?

riki2321 said:

You can rape imps

wut

[scifista42]

Doomkid said:

And hey, I think all those built in lighting effects alone, show how much vision they had

That may be imagination, not vision. Imagination means having good ideas and implementing them. Vision means efficient planning things ahead. Their lack of vision is apparent due to many linedef actions and other features lacking flexibility. They only come in 1 or several variants, because those were what the designers needed back then at the moment. They didn't care what other variants of the same feature would come in handy for mappers in the future.

[Doomkid]

I wasn't aware that vision was synonymous with foresight, I thought it would be applied in a different sense, for example "ID software made their vision of DOOM come to life". I didn't realize that it necessarily meant vision into the future but I guess that sorta makes sense.

[scifista42]

Well, the "different sense" you mentioned above kind of is a foresight, too - foresight of appearance of their finished game, envisioned while the game was still in development. I described foresight as taking future needs into account, but now I'm doubtful if this "sense" was the more or the less fitting one in this case. Maybe it's actually one and the same thing in principle, after all.