Things about Doom you just found out

[SaladBadger]

ah, in this case, it's voodoo doll fuckery. part of that particular encounter, if you back up enough, causes a crusher to come down and crush a voodoo doll. That voodoo doll dies before the spiderdemon kills the body your controlling, causing the oddities.

[The_MártonJános]

Aside from the blood stain, the textures MARBLE1 (patch MWALL1_1) and MARBLOD1 (patch MWALL1_2) also differ a bit in the marble pattern at the top.

[elend]

Haha nice, never noticed before. Odd change..

[KVELLER]

 

They weren't even trying to hide the gun's acronym, huh?

[Alfonzo]

A quote from Myk in 2010, exactly one day before I joined the forum:

 

On 1/28/2010 at 9:40 AM, myk said:

In the original game, all 8th levels have less sound attenuation. This didn't survive into source ports because Paul Radek's sound code was excluded from the source release due to copyright reasons. Chocolate Doom reincorporated the phenomenon, as it aims to closely imitate the DOS executable.

 

Some off-map monster batteries I have made for a certain E4M8 are teeming with bad guys, and their mosh pit moans can be heard all over the map in Chocolate Doom. Knowing that sound terminates at around 1200 units I was confused and went digging into the past for answers. This interesting find appears to be the culprit.

 

I wonder how far out I'd have to push the batteries to get those barons and cacodemons to shut the hell up.

[zokum]

That piece of code is there to make the boss monster audible no matter where you are. I think this tweak makes the most sense on e2m8, where there's a high chance you will wakup up the cyber by first attacking the lost souls and the boss will be far away. On the other maps it isn't all that important. It got carried over into Doom 2, so map08 has that slightly different audio model as well. The game just checks if it's map 8, regardless of what episode, and Doom 2 has one episode internally.

[KVELLER]

The enemies seem to have an autoaiming system like that of the player. You see, I was playing a map and encountered a Spider Mastermind, which of course wanted to turn me into swiss cheese, so I quickly took cover behind a tall pillar that had a Baron at its top. Lo and behold, the Baron got hit and they started infighting!

[kb1]

28 minutes ago, KVELLER said:

The enemies seem to have an autoaiming system like that of the player. You see, I was playing a map and encountered a Spider Mastermind, which of course wanted to turn me into swiss cheese, so I quickly took cover behind a tall pillar that had a Baron at its top. Lo and behold, the Baron got hit and they started infighting!

Yeah, you can direct them like that. The AI movement system is almost like Pac-Man - run map 30 in IDDQD mode while watching the automap, for about 30 minutes, then noclip around the outside of the map, and watch the monsters follow you around without being able to see you! They're like ants!

 

And, yeah they have no qualms about trying to shoot you "through" other monsters, which gets the party started!

[KVELLER]

10 hours ago, kb1 said:

Yeah, you can direct them like that. The AI movement system is almost like Pac-Man - run map 30 in IDDQD mode while watching the automap, for about 30 minutes, then noclip around the outside of the map, and watch the monsters follow you around without being able to see you! They're like ants!

 

And, yeah they have no qualms about trying to shoot you "through" other monsters, which gets the party started!

 

Yeah, but what I'm getting at is that this Baron was pretty high up, while the spider was at the same Z-coordinates as me. It aimed up for no apparent reason.

[kb1]

11 hours ago, KVELLER said:

 

Yeah, but what I'm getting at is that this Baron was pretty high up, while the spider was at the same Z-coordinates as me. It aimed up for no apparent reason.

Maybe it had already been hit by the baron, so it was retaliating?

[KVELLER]

2 hours ago, kb1 said:

Maybe it had already been hit by the baron, so it was retaliating?

 

Nope, not at all. I literally triple-checked to make sure.

 

It was in one of the maps in Ultimate Doom the Way id Did, can't remember which one exactly but it was the first appearance of a SM.

[TakenStew22]

3 minutes ago, KVELLER said:

can't remember which one exactly but it was the first appearance of a SM.

E3M8: Dis.

[KVELLER]

1 hour ago, TakenStew22 said:

E3M8: Dis.

 

I'm talking about UDTWiD though, not the base game :P

[TakenStew22]

1 minute ago, KVELLER said:

 

I'm talking about UDTWiD though, not the base game :P

Oh, sorry. XD

[Aquila Chrysaetos]

E4M4, possibly.

 

I've noticed this, too, but only with hitscan enemies, never projectile throwers. I've seen a particular situation in which a Mastermind attempted to infight a baron above it, but it seemed to be too close to the wall, and all of its shots landed straight ahead, as if the Mastermind needed to use autoaim to hit the target.

[Loud Silence]

In Doom e1m4 is a four-door room with blue keycard. One time i ran out of that room just in that moment when doors were closing, that door opened back and got stuck. I watched for couple minutes - that door didn't close. It got fixed when i activated all doors again.

[kb1]

There is a bug in Doom with targeting that occurs when a monster and its target are a different heights. I've been on a ledge watching imps below on a platform try to shoot me, and the missiles end up always hitting the wall below me, over and over again. I haven't researched the cause. Might be the inaccurate sine/cosine/tan tables, the fixed-point math, or an honest-to-goodness bug. It's probably a consequence of adding a small offset to the missile's Z-coordinate each tic, causing a compound round-off error.

 

That's my guess. But I don't think that solves your issue. From what you describe, my money is on the spider targeting the baron out of retaliation. @KVELLER I know you say you checked, and I believe you: But, how did you check, exactly? You'd have to debug the game, and check the Spider's .target field at the proper game tic, to know for sure. If this isn't the opening room of the level, can you say for sure that the baron (or something behind him) didn't hit the spider? Why else would the spider fire up there, if you were down below? It doesn't make sense - that just doesn't happen in Doom, as far as I've seen.

[Fonze]

All hitscans have autoaim applied to them; don't you people play doom?

 

https://i.imgur.com/VOlShbD.gifv

Edited December 5, 2018 by Fonze

[ketmar]

yeah. hitscan attacks all use `Aim` call to calculate a direction. for monsters it has slightly smaller range than for player, but otherwise it is the same. so you can use some monsters as meatshields even if you aren't perfectly hidden behind them.

[Gez]

On mardi 4 décembre 2018 at 4:18 AM, KVELLER said:

The enemies seem to have an autoaiming system like that of the player. You see, I was playing a map and encountered a Spider Mastermind, which of course wanted to turn me into swiss cheese, so I quickly took cover behind a tall pillar that had a Baron at its top. Lo and behold, the Baron got hit and they started infighting!

Yeah, all hitscans work that way. That's one of the cases where Doom is truly 2.5D: the monster aim at you, then the game runs a 2D trace in the monster-you line to see what is in the way, and then the trace's slope is computed from the vertical position of the first thing met.

[Lollie]

3 hours ago, kb1 said:

@KVELLERThere is a bug in Doom with targeting that occurs when a monster and its target are a different heights. I've been on a ledge watching imps below on a platform try to shoot me, and the missiles end up always hitting the wall below me, over and over again.

Just saw two video examples of this bug a couple weeks ago, it's funny just how easy it is to reproduce it.

 

 

[Linguica]

Fireball targeting has an inaccurate vertical component. The game attempts to calculate what vertical angle to launch the fireball at by determining the distance between the monster and the player. Unfortunately it uses P_AproxDistance which works by taking the X and Y differences, but instead of taking the hypotenuse of the triangle, it just takes the larger of the two plus half the shorter. This number is invariably a little bigger than the "real" distance and so the fireball is pitched at a less extreme angle, since the game assumes the fireball will be traveling further than it really is and will have more time for its vertical position to change. The ultimate effect of all of this is that any time a monster shoots a fireball on a vertical angle, it always underestimates the angle, and if the monster is approximately on a diagonal from you (so the X and Y values are about the same), the magnitude of this error will be magnified.

 

If a monster is at a sufficiently great angle above you, its fireballs will always pass over your head. You rarely notice this, though, because the monster must be at a nearly 45 degree angle above you, and in Doom you don't look up.

 

[Linguica]

Has anyone ever made a WAD exploiting this with Cyberdemons? I wonder if you could have a map where a bunch of Cyberdemons made a field of death with you ensconced safely at the center of it so long as you don't dare to move.

[Rathori]

35 minutes ago, Linguica said:

Has anyone ever made a WAD exploiting this with Cyberdemons? I wonder if you could have a map where a bunch of Cyberdemons made a field of death with you ensconced safely at the center of it so long as you don't dare to move.

 

That sounds cool, though I bet explosion radius on the rockets would make that pretty tricky.

[Dragonfly]

Elevate the player on a walkway so when the rocket misses it travels further, perhaps.

[KVELLER]

@Fonze @ketmar @Gez Glad to know I'm not insane!

 

@kb1 I guess you also learned something new today :) Just for the record, I checked by restarting the map and noclipping to the area of interest.

[DynamiteKaitorn]

So I know that the PC version and the PS1/PSX versions of DooM had slime trails but I was not aware this was the case for DooM 2 GBA. This is taken from MAP05: The Waste Tunnels.

 

[kb1]

10 hours ago, Linguica said:

Fireball targeting has an inaccurate vertical component. The game attempts to calculate what vertical angle to launch the fireball at by determining the distance between the monster and the player. Unfortunately it uses P_AproxDistance which works by taking the X and Y differences, but instead of taking the hypotenuse of the triangle, it just takes the larger of the two plus half the shorter. This number is invariably a little bigger than the "real" distance and so the fireball is pitched at a less extreme angle, since the game assumes the fireball will be traveling further than it really is and will have more time for its vertical position to change. The ultimate effect of all of this is that any time a monster shoots a fireball on a vertical angle, it always underestimates the angle, and if the monster is approximately on a diagonal from you (so the X and Y values are about the same), the magnitude of this error will be magnified.

 

If a monster is at a sufficiently great angle above you, its fireballs will always pass over your head. You rarely notice this, though, because the monster must be at a nearly 45 degree angle above you, and in Doom you don't look up.

 

Thanks for the concrete explanation. I think this is another engine bug, for which it would be nice to provide an optional fix for, but the fix would alter gameplay. I'd like to see the vertical component have a random component applied, so the monsters would have a chance vs. having perfect aim.

 

9 hours ago, KVELLER said:

@Fonze @ketmar @Gez Glad to know I'm not insane!

 

@kb1 I guess you also learned something new today :) Just for the record, I checked by restarting the map and noclipping to the area of interest.

I sure did!

 

[peach freak]

TNT Map16 (Deepest Reaches):

 

I learned while playing through TNT that the Blue Key is not required for finishing this level. You can go right to the Yellow Key from the start of the level. When you get past the first door, jump into the pit below and go left. There's a floor near where the stairs build to get out of the pit. When you step on this floor, it will rise and bring you up to a hidden area. At the top, go through the hidden door in front of you and then ride the lift down. While the lift is going down, there will be a window on the right near the bottom that you can run into. Once you run through it, you can work your way to the Yellow Key from here. Afterwards, you can go back the way you came from and go to the exit without needing to get the Blue Key and the Blue Door to get to the Yellow Key area.

[The_MártonJános]

In E3M3, the water is damaging.

But I am not only speaking about the "heavy water" around the bridge leading to the secret "furnace" area with the Berserk, the Backpack and the raising floor with the Pinky(ies). The "sink" just before the Invulsphere in the "cellar" (Sector 51) also does a good number on you if you decide to bathe a little. In fact, it's more damaging than any blood or nukage in the same map.

Also, the inaccessible parts of the nukage in the southeastern room (Sectors 12 and 15) are harmless - justified as they cannot be reached via nonlegitimate play -, and a small portion of the outside part of the "fenced balcony" next to the bloody pipe room with the BFG (Linedef 919) is (not set im)passable.
^{Okay, okay, I checked the map in DBuilder to be convinced that the Invul-water is indeed damaging and found more than I was inclined to.}