PSX Doom Glitching

[Lowerdark]

This glitch doesnt seem to be well known, so i made another video about it.

 

 

Things i learned about this

- When the map corrupts, vertex/vertices are moved usually to the x 0 y 0 coordinates. 4:00

 

- Linedefs with actions on them such as doors and buttons seem to only work on the original place of the linedef, 21:56,

other places they dont seem to work at all 19:20

 

- Sector heights can be moved too and change sector heights to a different value, probably from a sector in the map already. 20:20

 

 

 

Original video i made many years ago

 

Edited November 29, 2019 by Lowerdark

[Dexiaz]

18 minutes ago, Lowerdark said:

Original video i made many years ago

OH, SO THAT WAS YOU.

[Eurisko]

Was this touched upon again in that recent vid about the void?

[Lowerdark]

4 hours ago, Deⓧiaz said:

OH, SO THAT WAS YOU.

do i know you? :D

 

 

3 hours ago, Eurisko said:

Was this touched upon again in that recent vid about the void?

you name seems familier, what u mean about the void? the void i would say is the area of the map where no one should be, so probably outside the 23k mark according to what i can find on wiki's but i have no idea about the psx versions limits.

[Dexiaz]

2 minutes ago, Lowerdark said:

do i know you? :D

 

 

Not really. But I do know your old video. It was pretty interesting

[Dark Pulse]

I know Erick mentioned some of the limits in the GEC Master Edition project, but he hasn't mentioned any specific finite limits on map size. (If anything, we're probably more limited by RAM than the theoretical map size limit.)

 

If anyone knew that, though, it'd be him, since he's reversed the entire game.

[Eurisko]

1 hour ago, Lowerdark said:

 

 

 

you name seems familier, what u mean about the void? the void i would say is the area of the map where no one should be, so probably outside the 23k mark according to what i can find on wiki's but i have no idea about the psx versions limits.

 

Just had a dig around and it was this video I was thinking of. Another one from the brilliant Karl Jobst. 

This was definitely a topic on the boards recently. 

Its not about the PSX port but he does talk about the distorted textures etc....

 

Edited November 29, 2019 by Eurisko

[Lowerdark]

32 minutes ago, Eurisko said:

 

Just had a dig around and it was this video I was thinking of. Another one from the brilliant Karl Jobst. 

This was definitely a topic on the boards recently. 

Its not about the PSX port but he does talk about the distorted textures etc....

 

 

psx doom's wall are very sticky and i dont even think its possible to get such speed boosts, maybe a rocket boost could do it

[HeadshotTAS]

This glitch is actually decently well known at this point, and is also utilized in both speedruns of Doom 64 and Doom GBA. https://doomwiki.org/wiki/Linedef_deletion

In short, versions of Doom based on the Jaguar codebase don't track objects outside boundaries of the map properly, and the result is that parts of the memory get zeroed out (hence why the vertices go to 0,0 on the map.) Each piece of the blockmap that is out of bounds corresponds with a specific memory address, and walking over these pieces of the blockmap is what zeroes them out. Most of these addresses correspond to different parts of the map's memory, but I've also observed texture corruption when testing the glitch to its extremes on emulator. It isn't related to the all ghosts effect, but you can get similar results by playing around with it. Of course, you are able to exit the map as long as you don't corrupt too much of the memory beforehand. The game crashes on exiting if too much of the map gets corrupted.

[Lowerdark]

1 hour ago, HeadshotTAS said:

This glitch is actually decently well known at this point, and is also utilized in both speedruns of Doom 64 and Doom GBA. https://doomwiki.org/wiki/Linedef_deletion

In short, versions of Doom based on the Jaguar codebase don't track objects outside boundaries of the map properly, and the result is that parts of the memory get zeroed out (hence why the vertices go to 0,0 on the map.) Each piece of the blockmap that is out of bounds corresponds with a specific memory address, and walking over these pieces of the blockmap is what zeroes them out. Most of these addresses correspond to different parts of the map's memory, but I've also observed texture corruption when testing the glitch to its extremes on emulator. It isn't related to the all ghosts effect, but you can get similar results by playing around with it. Of course, you are able to exit the map as long as you don't corrupt too much of the memory beforehand. The game crashes on exiting if too much of the map gets corrupted.

 

that wiki actually got some decent information on the whole thing, seems like some code was changed/deleted in the process while making console versions that prevents linedefs/vertices to be moved to a new position.

[tsunstealer]

Does this exist on the Final Doom PSX game as well?

[Dark Pulse]

2 hours ago, tsunstealer said:

Does this exist on the Final Doom PSX game as well?

Might be trickier in Final Doom - the engine is definitely improved some and can handle some more complex maps in some ways.

 

But I'd say the fundamental flaw is still there, so the only difference may be that it's somewhat harder to trigger.

[Lollie]

 

Tmestamp 1:12:40 is a good example of the Linedef Deletion glitch being deliberately executed in a Doom 64 speedrun, and an explanation of how it's used in this specific case.

 

I'd say the hardest part of executing the glitch is really just getting the player out of bounds in the first place. Otherwise, it seems that all you have to do is run into the correct part of the out-of-bounds area. I'm guessing the same can be said for Final Doom — going by the wiki article that HeadshotTAS linked, Final Doom was when they added checks for Pain Elementals, preventing Lost Souls from spawning out of bounds where they can wander freely into memory.

[Erick194]

That yes that is a curious glitch, when I arrive in the part of the render maybe I will discover something, at the moment I have already compiled and tested a large part of the game's menu system in this new compilation.

 

[Lowerdark]

6 hours ago, tsunstealer said:

Does this exist on the Final Doom PSX game as well?

wiki says that theres a fix for pain elementals spawning souls outside map on final doom and doom 64, but the linedef glitch should still appear

 

1 hour ago, Lollie said:

 

Tmestamp 1:12:40 is a good example of the Linedef Deletion glitch being deliberately executed in a Doom 64 speedrun, and an explanation of how it's used in this specific case.

 

I'd say the hardest part of executing the glitch is really just getting the player out of bounds in the first place. Otherwise, it seems that all you have to do is run into the correct part of the out-of-bounds area. I'm guessing the same can be said for Final Doom — going by the wiki article that HeadshotTAS linked, Final Doom was when they added checks for Pain Elementals, preventing Lost Souls from spawning out of bounds where they can wander freely into memory.

 

hard to remake the lagg clipping glitch on an emulator, maybe with the right graphic settings its possible.

 

also had this message today while playing around in a corrupted map

[Jrmhd91]

I've been experimenting with the linedef deletion using some maps with a pain elemental and can see it has to do with the lost soul exiting the map from the top or right out of view. Here I have it done on Hangar, Threshold of Pain, failed on Command Center (as it was leaving the map from the bottom and left) and Military Base, ending with the cache miss on lump 0 error handle at the end of the vod. I am testing this out on a phat ps2 and original longbox copy of the game. 9:30 for the first clip - 

 

Edited December 6, 2019 by Jrmhd91
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