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Zed

What we don't know about Doom

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When I read threads like "Things about Doom you just found out" and "The Doom confessional boot" for example, I see a lot of things that I wasn't aware of (after several years of playing the game), and I'm sure that even a lot of "veterans" (from source port developers to speedrunners) didn't know about, so basically my question is, is there anything we don't know yet about the Doom engine? Are there still unanswered questions? How complete is our knowledge about Doom?

Basically, that's it. I don't have a lot more to say, I would like to know your opinion.

Good day.

EDIT: Another example I just remembered: the linguortals.

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To this day nobody knows what causes visplane overflows..... or atleast me. I don't even know what visplanes themselves are..

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I've read this article before, but still don't quite get it. Does it mean 128 unique flat textures, or also different heights/sectors, not only textures?

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ChekaAgent said:

I've read this article before, but still don't quite get it. Does it mean 128 unique flat textures, or also different heights/sectors, not only textures?


Two sectors against each other with floors that have the same flat (floor texture), height, and light level count as one visplane. Change any one of those three qualities and the floors become two visplanes. The ceiling counts as another visplane. If the floors are the same but the ceilings are two different heights, then you'll have 3 visplanes, one for the two floors, and one for each of the different height ceilings, if that makes sense. This all depends on what is present in the players field of view.

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This isn't related to the engine at all, but I believe there's a lot of people that still want to know the source, or rather the origin of the rocket launcher sprite.

Now, what about what's been left to be confirmed by the original members of id software?

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Items on the Doom Wiki hitlist of facts we don't know. Most are about the console versions, since the PC development history and details are almost exhaustively known.

  • Who edited the levels for the console versions of Doom?
  • Who created extramap.wad and what was it for?
  • What exact day was the 32X version released on in the US?
  • The exact date Tom Hall was fired (it was near July 4 but nobody knows exactly)
  • Were nightmare imps in the PSX press beta accidental or intentional, and if intentional, why were they removed before release?
  • Why didn't Williams finish TWM01.wad for Final Doom PSX?
  • Who authored the series of exclusive deathmatch maps for GBA Doom?
  • Who did all the additional coding work for Ultimate and Final Doom? (Likely Dave Taylor, but nobody's either attributed him, nor has he ever claimed doing it)
  • The original source code has references to an Episode 5 for Ultimate Doom, and maps 33 and 34 for Doom II. Were these ever actual considerations or just detritus of development?

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Does anyone know what lead to Doom II on the GBA being developed on the Southpaw engine? Did they simply decide it would function better on GBA hardware than whatever modified console port they used for the first one?

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Why did id Software remove the unused gore assets?

Why did id Software remove the assault rifle?

Does Episode IV take place on Mars or on the Moon? Or is it on Earth?

Why did id Software not design a new boss for Episode IV?

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DoomzRules said:

Why did id Software not design a new boss for Episode IV?


It's an obvious one: they were busy with Quake, so they didn't want to spend much time on Ultimate Doom.

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ChekaAgent said:

It's an obvious one: they were busy with Quake, so they didn't want to spend much time on Ultimate Doom.


Still... it wouldn't have hurt to make a new boss ya know. Just saying.... I mean it would have made Ultimate Doom more memorable IMHO.

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With 99% certainty I can say the reason for the bounding boxes on Tom's maps was because he wanted the layouts to be consistent with the planned overworld map for Tei Tenga that you see in COMPSTA2 and Alpha 5's placeholder intermission screen.

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Marnetmar said:

With 99% certainty I can say the reason for the bounding boxes on Tom's maps was because he wanted the layouts to be consistent with the planned overworld map for Tei Tenga that you see in COMPSTA2 and Alpha 5's placeholder intermission screen.

Yeah I'd say that's 100% confirmed really. CSG matched the shapes up and everything, and besides that Tom's vision was to have a continuous world concept, more like Strife, so locations would need to be consistent with their "overworld" depictions to assist and enable that.

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Linguica said:

You have also mentioned a timer running at 140hz, pushing sound to the sound card four times per tic. Was that a DMX thing, or what?


Yes, see I_StartupTimer in I_SOUND.C from Heretic or Hexen sources (still looks the same in Doom v1.9 binaries). It does TSM_Install(SND_TICRATE) and SND_TICRATE is 140Hz. It is commented: "installs master timer. Must be done before StartupTimer()". After that it uses TSM_NewService to instruct DMX to call I_TimerISR (which increments the tick count) from I_IBM.C at the perhaps more familiar 35Hz rate.

I_StartupSound also passes SND_TICRATE to DMX_Init as the first parameter (this happens after I_StartupTimer has already been called a few lines earlier from the same function).

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As Ling's questions make clear, most of the things we don't know at this stage are on the "human" side - why were things designed this way? Why was this done? There's very little left now in terms of technical things we don't know - we've had the Doom source code almost 20 years now. Most of the stuff not covered by that has been independently figured out.

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But the source isn't the DOS binary's source. So stuff like the VGA mode used aren't available, right?

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fraggle said:

we've had the Doom source code almost 20 years now.


I struggle with conceiving of the passage of time. 20 years!

VGA said:

But the source isn't the DOS binary's source. So stuff like the VGA mode used aren't available, right?


Not from the source, but it's pretty easy to figure out from the binary itself. I didn't think there was any controversy about what mode it used.

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fraggle said:

There's very little left now in terms of technical things we don't know - we've had the Doom source code almost 20 years now. Most of the stuff not covered by that has been independently figured out.


Well, we still don't have Doom 2016's source code, so there are still a lot of unanswered questions about Doom 2016.

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Linguica said:

What was your process for adding new line actions to the game? Was it ad hoc as you came across a situation where you wanted them, or did you ever draw up a list of a bunch of things you knew you wanted to put it?
Why a line special for scrolling walls in only one direction?


I'd venture a guess that the question about scrolling in one direction points to an answer to the first question. They likely only added new line actions as needed, or at least there were a few very basic ones thought of ahead of time and then all these more specific ones were just added as needed.

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WHO THE HELL THOUGHT OF ALL THOSE MIND SCREWING MAPS, FOR HACX, WOULD BE A GOOD THING?

Really, its like Romero's abstract design x50.

Edit- Wait, this is about Doom... Still, it runs on the id Tech 1, so it should count.

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Voros said:

WHO THE HELL THOUGHT OF ALL THOSE MIND SCREWING MAPS, FOR HACX, WOULD BE A GOOD THING?

Really, its like Romero's abstract design x50.

Edit- Wait, this is about Doom... Still, it runs on the id Tech 1, so it should count.

The HacX developers are totally other people dude. Plus it's basically just a total conversion with a dehacked executable.

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Marnetmar said:

With 99% certainty I can say the reason for the bounding boxes on Tom's maps was because he wanted the layouts to be consistent with the planned overworld map for Tei Tenga that you see in COMPSTA2 and Alpha 5's placeholder intermission screen.

Oddly, despite Tom Hall's plans for more realism in Doom (based on his "Doom bible"), it's John Romero's E1 maps which look more realistic. Maybe Sandy Petersen's psychedelic texturing also damaged the potential realism from Hall's maps.

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The origin of Super Shotgun.

We know the every original models of Doom arsenals, except SSG (and a knuckle from fist). I do believe that the sprites of SSG were created with same methods; photographing toy weapon. I mean, It doesn't look like a drawn one for me.

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antares031 said:

I do believe that the sprites of SSG were created with same methods; photographing toy weapon. I mean, It doesn't look like a drawn one for me.


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DoomzRules said:

Does Episode IV take place on Mars or on the Moon? Or is it on Earth?


I'm pretty sure it's on Earth because the ending of Episode 3 seems to suggest it's on Earth and it's the tie-in between Doom and Doom 2, the latter of which obviously took place on Earth. He got out of hell, the Earth is suddenly swarming with hell, he fights his way through, and then at the end of Episode 4 really sees the extent of the damage while also finding Daisy's head. After that, during the course of Doom 2, he fights his way through to have the citizens safely evacuated before turning his sights to the portal he originally came out of so he can go back into hell to finish things, hence the latter half of Doom 2 taking place in hell levels.

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MetroidJunkie said:

I'm pretty sure it's on Earth because the ending of Episode 3 seems to suggest it's on Earth and it's the tie-in between Doom and Doom 2, the latter of which obviously took place on Earth. He got out of hell, the Earth is suddenly swarming with hell, he fights his way through, and then at the end of Episode 4 really sees the extent of the damage while also finding Daisy's head. After that, during the course of Doom 2, he fights his way through to have the citizens safely evacuated before turning his sights to the portal he originally came out of so he can go back into hell to finish things, hence the latter half of Doom 2 taking place in hell levels.


I always used to think it was the Moon, because I thought he got teleported to the Moon instead of Earth, received a distress call, and fought his way through the Moon to get to the Earth portal which is why he appears as is at the beginning of Entryway in Doom II.

Then again just my personal theory....

P.S Why doesn't MatPat ever do a Doom theory? Seriously, I mean it's Game Theory! Not FNAF Theory or any other theory... seriously, I feel like he doesn't cover Doom at all... or just any other games except for fucking Five Nights at Freddie's or some other bullshit.

P.P.S That was a bit off-topic, but I totally wish MatPat would make a Doom theory. Would make for an interesting watch to say the least.

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