Things about Doom you just found out

[Spectre01]

The soldiers walking along this top ledge in e1m4 don't attack or shoot back if you stay in the tunnel and do not enter the room. Not really sure what causes it.

[wallabra]

Just now, Spectre01 said:

Not really sure what causes it.

 

Might be a REJECTS bug?

[Salt-Man Z]

On 7/17/2021 at 6:36 AM, Gez said:

It's a "sound tunnel", which lets the noise of the player attacks reach the monster closet so that the monsters wake up and start wandering into the teleport lines.

 

I always wondered why the visible holes were never covered up with a midtex or something, or is it just that no one thought of that back in the day?

[Albertoni]

3 hours ago, Salt-Man Z said:

I always wondered why the visible holes were never covered up with a midtex or something, or is it just that no one thought of that back in the day?

 

They were nearly invisible at 320x200

[spd7693]

On 8/17/2021 at 7:23 PM, HAK3180 said:

When you telefrag something , apparently how much overlap there is between the two hitboxes matters, such that the corpse can go flying, similarly to when rocketed or barreled, when telefragged "at an angle." However, this only seems to be in effect in less advanced ports.

 

Happened in @Altima's 24-hour stream on Doom's 20th anniversary. In TNT map 7 he telefragged a shotgunner, the shotgunner flew off and teleported onto the (bigger) platform where the teleporter to the red key is. It was one of the funniest highlights. 

[RjY]

On 8/22/2021 at 4:27 AM, Spectre01 said:

The soldiers walking along this top ledge in e1m4 don't attack or shoot back if you stay in the tunnel and do not enter the room. Not really sure what causes it.

 

On 8/22/2021 at 4:29 AM, Gustavo6046 said:

Might be a REJECTS bug?

 

It is. Sectors 81 and 93 are mutually blind to each other in both directions.

There are a few other places where sight is blocked. The most interesting being that sectors 97,119,121 are mutually blind with sectors 113,116,117. That is, the room by the nukage river with quarter circle of barrels, and its continuation to the west, are invisible to the stairs beyond (those that lead up to the hub containing the blue key). If you run through to said stairs, the monsters that follow won't attack until they reach the bottom stair itself.

 

The full list of sector pairs which were mutually blind in the original but which ZenNode's reject builder found a direct line of sight: 1,32; 6,120; 12,19; 16,37; 33,42; 37,48; 49,57; 77,129; 81,93; 85,120; 97,113; 97,116; 97,117; 103,111; 103,120; 113,119; 113,121; 116,119; 116,121; 117,119; and 117,121.

[El Juancho]

The reloading sounds of the super shotgun in final doom has a lower sample rate than the sounds found in doom and doom2 wads

[sincity2100]

On 7/26/2021 at 7:26 AM, SiFi270 said:

Three of Tom Mustaine's maps were rejected, but none of those seem to be because of poor quality. One was too short (and became TNT Map01), one was too similar to a Doom II map, and with the last I don't think it's been officially stated, but it seems it was already avaiable as Map06 of #1dwango, and id didn't want any of the Master Levels to be something already available online. It still became Map17 of TNT.

 

Then there are Christen Klie's maps. While I don't like a single map he's made, (and keep in mind, I'm okay with pretty much everything else in the Master Levels) I think it's more likely some of his submissions were rejected because otherwise almost half the project would just be his maps, which wouldn't be fair to the other contributors.

And yet he got 6 map slots for some reason.... -_-

[Sergeant G]

I only recently learned about the existence of tics (realtics and gametics).

I had no idea those were running in the background. 

[Okej5722]

Infinitely tall monsters always existed.

[HAK3180]

Except in GZDoom, the TNTEM cheat kills pain elementals in such a way that they spawn lost souls as normal, which are also immediately killed. This has major implications for the number displayed after using this cheat. If you have a map with nothing but 10 pain elementals and you immediately type TNTEM upon starting the map, it will say "40 monsters killed," and your kill count will say 10/10.

 

Also, precisely where the pain elemental is matters. If it's in a corner and can't spawn three lost souls upon its death, TNTEM may only credit you with two phantom kills. 

 

So it seems GZDoom is best for determining actual initial monster count.

[Edward850]

7 hours ago, Okej5722 said:

Infinitely tall monsters always existed.

No infinitely tall monsters exist. No entity in Doom is infinitely tall.

[kevansevans]

18 minutes ago, Edward850 said:

No infinitely tall monsters exist. No entity in Doom is infinitely tall.

 

I actually had a chance to VC with John Romero recently and took the opportunity to ask him why enemies had infinitely tall collision boxes. The short answer of it is that they didn't have enough time to program in the code necessary to handle the player landing on top of enemies, and that otherwise it wasn't impacting the players experience in any meaningful manner. This is why this feature exists in Heretic, as it granted another several months to refine the source code.

[Edward850]

15 minutes ago, Kevansevans said:

I actually had a chance to VC with John Romero recently and took the opportunity to ask him why enemies had infinitely tall collision boxes.

I'm going to be nitpicky and point out again that they don't have an infinitely tall collision box.

Remember, all projectiles and hitscans can pass over or under objects, and moving enemies can be blocked by low ceilings, both elements that require a height to be defined.

What's missing is solid objects never check Z heights for collision. They basically only do half the check. The height is still there and still part of the collision, it's just not used in that particular routine (indeed for the reason you got from Romero). It's used everywhere else however.

[slugger]

You can "dance" with revenants by baiting them into a punch and then backstepping it, just like pinkies. If you're fast you can completely seal one off from firing missiles altogether. I used to think you couldn't reliably win boxing matches with revenants, but you can.

[tescari]

I wasn't crazy! Map2 in Doom 2 had bars on the left switch! But that was a different version of the game.

[MemeMind]

5 hours ago, tescari said:

I wasn't crazy! Map2 in Doom 2 had bars on the left switch! But that was a different version of the game.

Yep

[axdoomer]

I liked the 1.666 version of MAP02 better. 

[DaAndroid614]

i decided to buy masters of doom a while ago, and it describes imps as "a red-eyed Bigfoot-like beast with brown fur covering his muscles and metal spikes protruding from his shoulders and arms", so i guess even if we didn't get fuzzy shamblers, we do at least get fuzzy imps

[SaladBadger]

Decino did a vid recently about mancubus fireballs going through walls, which is pretty well known but something interesting I learned recently is that this wasn't always a problem. In the old press release beta, things were separated into distinct classes, with only players going through what would become the normal movement code that the release game uses. Projectiles used a much simpler physics model where they performed a line trace based on their velocity, and if that was unobstructed, they did a full move. So, excepting any bugs in the line trace code, of which there are many, projectiles should never be able to go through walls, and they also have the interesting trait of being infinitely thin.

 

When every thing type was merged into the mobj type, I guess they decided it wasn't worth having special physics for projectiles and made them use the now normal movement code.

[DynamiteKaitorn]

Funnily enough I never realised projectiles could fly through walls in DooM. Now I know why I sometimes die in a D2 map and I'm behind cover.

[tescari]

On 8/27/2021 at 7:39 PM, Theperson said:

Yep

haha yea, that's the video that showed me! I thought I was going crazy

[Maximum Matt]

On 8/22/2021 at 1:27 PM, Spectre01 said:

The soldiers walking along this top ledge in e1m4 don't attack or shoot back if you stay in the tunnel and do not enter the room. Not really sure what causes it.

 

On 8/26/2021 at 9:08 AM, RjY said:

There are a few other places where sight is blocked. The most interesting being that sectors 97,119,121 are mutually blind with sectors 113,116,117. That is, the room by the nukage river with quarter circle of barrels, and its continuation to the west, are invisible to the stairs beyond (those that lead up to the hub containing the blue key). If you run through to said stairs, the monsters that follow won't attack until they reach the bottom stair itself.

 

Can't believe I'm still learning so much about this level - reject table anomalies, the area that could trap players in MP (early version), missing textures, that strafejump that bypasses the maze section, the SR50 jump to the exit, Sandy's assertation that HE has his fingerprints on this level (and apparently EVERY MAP in E1)... I think that this is now my favorite E1 map now...

[BladeWolf]

The skybox backdrop of Doom 2's city levels were of the Columbia shuttle taking off.

[Gez]

20 minutes ago, BladeWolf said:

The skybox backdrop of Doom 2's city levels were of the Columbia shuttle taking off.

A lot of Doom's original assets have been sourced over the year. There's more trivia like this on the wiki, if that interest you:

• Sky
• Artwork of Doom
• Musical inspirations
• Origins of Doom sounds

 

[RjY]

Baron Warning

In the original game, if you are about to face a baron of hell you get a large but sometimes subtle warning in the form of a MARBFAC3 texture.

This applies in episodes 2 and 3, on regular (non-secret, non-boss) maps. Obviously E1 is an exception where they wanted the bosses to be a surprise, and it doesn't work in E4 which was designed long afterwards. Finally, it only works on hurt me plenty: more evidence the maps were designed around that. There are many more barons on ultra-violence.

Otherwise this design motif seems remarkably consistent: there is enough of a correlation to claim it is deliberate.



Although annoyingly there are exceptions, aren't there always..? On E2M5, this poor fellow in a cage must have done something terribly wrong to be left a sitting duck by hell's management. I think he's there so you have something on which to test the powerful weapon you retrieve from the well-hidden test chamber beyond. (I like to think this would have been where you found your first BFG, if they hadn't decided to swap the episode order at the last minute, but that's speculation.) Then on E3M4, there's another baron behind the wrong type of marbface. I can think of no obvious explanation for that one.



Inspiration: I looked into this after replaying E2M7 and being struck by the sheer random out-of-place-ness of the MARBFAC3 by the blue door. It looks like, well, a texturing error, a misclick that left the wrong texture on the wall. It was enough to make me curious to go off and search for all occurrences of MARBFAC3. The pattern revealed itself from there. I assume the DTWID people have a huge dossier of observations like this. I do wish they would publish it. Although I suppose it's more fun to discover things yourself.

[The_MártonJános]

I looked at E4M3 in Doom Builder to see what that skull switch in the alcove near the red skull did (re-lowered the thick metal column at the entrance of said alcove that would rise if you shot through one of its lines.) While fiddling around to see if there are any hidden triggers, I noticed an amusing detail:

Each and every single instance when there's an upper or lower texture applied to a linedef, the same texture is set to be both the upper and lower texture on both sides.

Shawn Green sure wanted to make sure no missing textures were present. I mean, this was still preceding the implementation of Visual Mode, so kinda understandable.

[DeathWalkerGT]

Yesterday I played the Fortress Of Mystery level for the first time without accesing it from the console...it was just by luck...

Nice hard map with the spartan detail very apparent

[Uni]

@RjYThat's a really interesting find! Your thoughts about the texturing error on E2M7 were my thoughts exactly. I never understood why there was a random marble texture besides that door but now reading your observation it makes perfect sense. Thinking about this motif, it really feels like something Sandy would do to warn the player about powerful foes, take advantage of the texture set and adds lore to the levels.

 

 

Edited September 13, 2021 by Uni

[RjY]

@Uni Thank you for reading all the way to the end. ;) You mention Sandy's penchant for adding lore: I wonder about all the other subtle "visual narrative" I miss because I'm running around at 20+ miles per hour shooting at demons. Some things I've read about, and been surprised to learn, in the past few years:

• Dead marines in episode 1. Starting from E1M5 there are no more marine corpses. Implying you are the first one who has made it that far. Did you pay attention to the placement of player corpses? Or did your brain, like mine, quickly learn to tune out decorative objects that have no obvious gameplay effect, to avoid distraction from the main goal of not getting killed.
• The altar scene in E3M6. Are those demons worshipping human technology, in awe of its destructive power? I don't know, I didn't even stop to look. I just jumped down off a ledge to grab some weapons off a pedestal -- and unsurprisingly, got ambushed. Supposedly there, it is also shown how lost souls are created, from the ritual sacrifice of imps. Would you notice this when the monsters all wake up on sight and immediately move out of position? Would you notice afterwards that the imp corpses are specifically placed, they are not just regular monsters that happened to fall there in combat? I didn't. Fun fact: they are the only placed imp corpses (thing type 20) in all of Doom and Doom2.
• The Remorseless Eatin' Machine of E2M4. You walk in the room -- the floor drops -- you're surrounded by monsters -- you can't back out. You dive for cover through an odd-looking machine -- argh! The ceiling! Too late you realise what all those blood pools were telling you. But do you notice, in your haste, that the machine has two eyes and you just ran into its mouth? You can even "kill" it if you shoot at the right spot. I paid no mind to the placement of the eyes for nearly 20 years, because again, the brain tunes out decorative objects with no gameplay effect. Nowadays, I wonder if the evil eye sprites were created specifically for this construct.