MS-DOS Doom II Freak Scrolling Walls Trippy Glitch

As I was testing out one of my WADs in the MS-DOS Doom II executable in DOSBox, I found this freaky glitch. It involves all of the walls scrolling for some reason due to some error. I've encountered this error in MAP29 of my megawad Illuminatus.
List of various Doom error messages:
doomwiki.org/w...
Illuminatus:
www.doomworld....

[@Aquarius199]

As I stated before in a community post, I've been working on a new 32 map vanilla megawad, as more information about it can be found here: www.doomworld.com/forum/topic/133235-eternity-32-level-megawad-for-tnt-evilution/

[@DoomHydra]

A megawad, that's awesome man! It's a good outlet to put your doom time into if you're cooling it on the videos. I'll keep a close eye on that, I'd love to play it on my channel when it comes out

[@blackmendosa]

I've recently started to learn how to map for Doom. Your videos are partly to blame hah.... that and my love of Doom 2 (Honestly surprised it took me this long to finally learn how its done). Maybe one day I'll have a map pack to show you Aquarius!

[@christopherthibeault7502]

Nice to stop by this channel again. Someone downstairs in the comments suggested that MAP29's block-map exceeds 65536 bytes as the Vanilla code uses a 16-bit (65536-digit) integer for its register. This means the game's memory corrupts, preventing you from saving data or experiencing proper level geometry. It's akin to the Block Overflow Glitch where a single hit check exceeds a certain number and all collision detection dependent on said grid stops functioning. In that case, Melee attacks still work, but hit-scans and projectiles do not. Everything clips through the walls, too--never a pretty sight. If I recall, Illuminatus was either tested solely on or perhaps tailored to a source port--ZDoom if I recall correctly. I can only recommend you reduce the playing field of MAP29, not only to freshen its pace but also to dodge the many, many bullets of Vanilla limitations. Snipping down excess geometry allowed for PS1 Doom and that philosophy shaped Doom 64's unique style for the better. At the very least, hit up Vinny of Vinesauce. EDIT: The error message about searching for a named file in the WAD might be further evidence that MAP29 itself might be the culprit. Also, since it managed to wreck DOSBox and corrupt your Doom II executable, should you ask Doomworld for help, make them privy of that fact in case someone wishes to test and replicate the glitch as part of a diagnosis.

[@minscandboo1213]

Bro found the farlands in doom

[@CyberSZ]

LMAO

[@matheusjardim2378]

01:12 The textures: "Scrolling" Me: *A G O N Y !*

[@eljaminlatour6633]

Someone call Decino.

[@Saver310]

Better Call Decino!

[@noctis_fella]

I better call Decino!

[@funsizeskittles4223]

“Oh wow, that is not supposed to happen. Let’s take a look at the code and see the files for the game’s textures”

[@idogaming3532]

Memory Corruption.

[@Flesh_Wizard]

ShrooM II: Tripping on Earth

[@ItzAmirnite]

Aquarius199 is the perfect youtuber to binge watch and eat chicken bites, also happy new year!

[@aliengenie8896]

Something in that area of the map is causing memory corruption somehow. I can't really prove it, but I think it may be related to the Blockmap (maybe the blockmap is too big for Vanilla Doom to handle?) I'm not just throwing darts at a wall, here. You have a map with a very large area, and I noticed that what seems to be triggering it is: 1) You enter that area of the map, or 2) You fired your SSG near that area of the map with monsters on, causing monsters in that area of the map to move around. Both of these would cause writes to the Blockmap in certain areas, and if there's something about it the game didn't like, it's possible that it's overwriting important memory related to rendering instead. Apparently, it's also overwriting the map number, too, hence the strange error you got when trying to respawn.

[@Titanic4]

Given that blockmap is used for both collision and intercept checks, shooting tracer based weapon after going through teleport in starting area of MAP29 with -nomonsters launch parameter specified may also cause game's instability. Firing projectile based weapons will most likely cause instability as well. Even moving around is enough to cause memory corruption in affected areas.

[@atlas_287]

its called the all ghosts effect- it happens when a hitscan attack intercepts at least 147 linedefs (things) and so, memory associated with the blockmap gets gets illegally overwritten

[@aliengenie8896]

@@atlas_287 No. This is not the classic all ghosts effect. The effects are completely different and the intercepts overflow can only happen when shooting hitscan weapons. This one is even occurring when an actor moves around in a certain area of the map. On top of that, the all ghosts effect disables all collision completely. But you can see the player getting stuck on invisible walls here.

[@maggieberray5021]

This map is so cursed and demonic, even the Game Glitch Gremlin is like, NO NO NO, YOU'RE NOT DOING THIS 🤣

[@Saver310]

He shit all over the level with his glitches, out of fear.

[@usernameak]

Neat. Some memory corruption.

[@mysticalacer94]

Have a happy new year 2023, Aquarius, nonetheless.

[@maxlefou]

that would make good materials for a doom creepypasta

[@AlexeiVoronin]

Curious. The vanilla engine still has a bunch of weird bugs that are discovered nowadays (plus a number of old ones that were fixed in various patches, like the moire effect). Maybe related (or not) - in vanilla Doom 1 / Ultimate Doom, in E1M8, go into one of the northern corners of the big yard before the level end (i.e. the northeast or northwest one). Turn around to face the pentagram building (or the platform with the teleporter) and shoot a hitscan weapon in that direction (chaingun works best). You should observe your bullets hitting some kind of "invisible wall", though projectile weapons are not affected, and nothing stops your movement. The effect can be observed even if you move away from the corner a little bit. Bonus: If you're using a very old version of the engine (1.0 or 1.1), the pentagram building would also start glitching out when looking at it - I think this was due to a hardcoded drawing limit, which was raised in later versions.

[@Titanic4]

What you've just described is the all-ghost effect. Doom's engine has intercept array, which is 127 elements long. If there's enough intercepts in the array, the blockmap will get corrupted. Such effect can occur if the bullet gets stuck due to rounding error, or when there's more than 127 different actors in the ray trace. Back when the game was originally released, floating point operations were very expensive in terms of performance. PlayStation version of Doom could also behave strangely if a monster happens to be out of bounds. Eventually, memory corruption will occur, causing major visual glitches, which will lead to game crash. Memory layout can be different from version to version and such memory corruption will give different results.

[@andrewkruchoski7757]

Lilith strikes back...

[@papasrod]

it's even more creepy without monsters

[@GreatFox42]

Isn't the tutti-frutti effect something that only happens with walls? It's unheard of for it to corrupt flats AFAIK. I echo the suggestion of another commenter and trying this in Chocolate Doom. If it breaks too, then that means the problem is with your map...somehow. If it runs it fine, then the issue is either with your DOSBox or your Doom II exe. Also where'd you get that sky texture?

[@Titanic4]

The tutti-frutti effect could also occur due to game bug, which just so happens to cause memory corruption in location, where the textures are stored.

[@Titanic4]

Interestingly, I've tested this on VMware emulator and the game crashed too. There's very high chance that the game can't properly handle the MAP29 as I've managed to reproduce the issue on real hardware. Also, when I tried to access the affected area on my Devils Canyon powered PC(i5-4690K, GTX 970, 32 GB DDR3), the game quit with Machine Check error message shortly before rebooting. Also, forget about saving the game on MAP29. The game crashes if you try to do that due to buffer overflow. I've checked the map with DeePsea editor's statistics feature and according to it, the blockmap is unusually large, which could explain game's major instability. Vanilla MAP15 doesn't even come close to that. The statistics feature is also able to determine approximate save file's size, should one be created successfully, along with game's save function buffer size, for comparison purposes.

[@aliengenie8896]

Other evidence also points to the same conclusion (the memory corruption occurs when a solid mobj_t starts moving around in that area of the map) so I think you're 100% right. The maximum allowed Blockmap size is 65536 bytes, probably because the code that deals with the Blockmap it uses 16-bit pointers.

[@Saver310]

Please continue this nerdy conversation, I love them

[@battleonfan1]

This is giving me flashbacks to my bad THC edible trip

[@KayX291]

Have you checked if it happens in other DOSBox forks as well, especially DOSBox Staging? That one has a lot of QOL features and fixes while being more modern PC friendly by using modern libraries unlike the normal DOSBox.

[@wadmodderschalton5763]

This is the cursed doom images thread brought to life in the Doom engine.

[@JoLiKMC]

Gonna ask the obvious question: does it work under _Doom2-plus_ or _Boom?_ If so, then the map is probably just too big for vanilla _Doom_ to handle. Check the _Doom Wiki_ for a list of static limits. It might help.

[@zaphael0]

Wondering if it has something to do with the sectors being too large.

[@alobowithadhd6191]

My thoughts exactly. But now that you mention it, why doesn’t NUTS.WAD have this effect?

[@lethalbroccoli01]

@@alobowithadhd6191 does nuts split the sectors up?

[@Titanic4]

​@@alobowithadhd6191 MAP01 from NUTS.WAD has blockmap, size of which doesn't exceed the static limitation of 65534 bytes. You can load this WAD in original Doom 2 just fine, however the game will lag horribly, unless you specify -nomonsters launch parameter.

[@Titanic4]

​@@alobowithadhd6191 MAP01 of NUTS.WAD is huge, all though its blockmap isn't large enough to cause memory corruption. Initially there's not much slowdown due to fact that all the monsters in main room are in idle state. Once the shot is made, the sound propagates through entire room, waking up all the monsters, causing massive slowdown, especially if projectiles are involved.

[@alobowithadhd6191]

@@Titanic4 Not sure why I used the words “my thoughts exactly.” I can’t say I’m very informed on what is going on here.

[@atlas_287]

This is called the all-ghosts effect

[@dragonaut8382]

DooM II : psilocybin version

[@AkumuVids]

We're gonna need a few turbo nerds to explain this one. I can't say I've ever seen the game bug like this before.

[@TheDamonGant]

When’s the next time you’ll play and review more wads? Because I sent you links to ones I made a few months back

[@Arkl1te]

6:04 "Illegal read from ..." also known as the game being like: "What's this? I don't think this isn't even remotely Doom related data but I'm processing it anyway, let the player sort it out!" Player: "dafuq is happening?!"

[@spcellAI]

Hi Aquarius. Could you please tell me if you accept WADs made with Obsidian Level Generator? It's a tool which generates WADs by the settings you set.

[@lod4246]

If you''ve messed around with it enough, you'll be able to notice various prefabs and patterns with how it generates levels. But here, not only is it way too big and expansive, there's a lack of signs and stuff that would indicate it was procedurally generated. Level generators are generally pretty looked down upon anyways, so it'd be pretty embarrasing for him to blatantly release something like that, since it takes significantly less effort to do than actually making the levels by hand.

[@szymon6207]

Have new year 2023 ?

[@DesertFerret7]

Never had I experienced this playing Doom back in the DOS Era with certain wads. Seems the DOS version of Doom 2 isn't compatible with that wad. I could be wrong though. Good thing for GZDoom!

[@Titanic4]

Modern sourceports are able to handle insanely large blockmaps just fine. Vanilla DOOM 2 has static limitation related to blockmap size, exceeding which will lead to memory corruption.

[@shirohimayumikira234]

This is probably a DOSBOX error, DOOM2.EXE's shit, or probably just the map causing these shenanigans. Either way, it's ridiculous! EDIT 1: Added the game EXE. I feel like it might be part of the issue.

[@Titanic4]

It's the map's blockmap that causes the issue. Blockmap is used for collision and intercept checks. If you happen to get the "All ghost effect" bug, you won't be able to damage enemies in any way due to blockmap corruption.

[@dilat]

Good map for LSD

[@samuelhamuel4689]

Doom but in 4D

[@InCompet4nt]

and this, is why chocolate doom is better

[@Titanic4]

Chocolate Doom wouldn't handle this map either. The creator of the video made some adjustments to layout in order to reduce blockmap size in order to prevent corruption from happening in the first place.

[@MeatySpag]

does this occur in chocolate doom?

[@KkarYTBoi]

tried playing it with Chocolate Doom, and when I went to the part where he noclips to the area and once, Chocolate Doom (game) crashed. so yes it occurs in Chocolate Doom.

[@KkarYTBoi]

either, it's probably only me who saw it occur.

[@cloud_s_97]

Have you tried increasing the ram on DOSBox?

[@Titanic4]

I don't think that will help in any way. Game's static limitations cannot be solved by increasing the memory amount.

[@alobowithadhd6191]

This might be an issue with how open it is. If this part of the map also is far away from the origin, that might have something to do with it too. Are you certain the map isn’t leaking and the sanity check didn’t fail?

[@mrcowboyzombie]

Pixels

[@yuricosta6354]

why the quality is only 360p?

[@Spartan122S]

Probably because it’s on MS-DOS

[@eljaminlatour6633]

That's how Doom is on vanilla.

[@yuricosta6354]

@@eljaminlatour6633 oh, so the poor quality is to give us spectators the hardcore vanilla experience ?? Come on, are you serious ?? (Btw Aquarius199 just fixed the vídeo quality)

[@GreatFox42]

@@yuricosta6354 It's just youtube taking a while to process the video, dude.

[@AlexeiVoronin]

@@yuricosta6354 Vanilla Doom runs on 320x200 - you can raise the quality on KZbin, but it will still be blurry :P

[@fatesquadron2332]

AI Generated Doom WAD video

[@lordterra1377]

Is this a raycasting glitch?

[@seankelly1047]

Oh

[@DerIntensiv]

Is this official lvl28 from doom2 ?

[@Titanic4]

This is MAP29 from custom megawad made by the creator of this video.

[@DerIntensiv]

@@Titanic4 oh ok

[@silverchain92channel]

Bro... Your files are corrupted.

[@AlexeiVoronin]

If that were the case, the symptoms would have occurred from the moment he started the game (saying this as someone who has seen corrupted copies of Doom before).