Things about Doom you just found out

39 minutes ago, Spectre01 said:

Apparently sprites disappear after very long distances in Software mode. Recently played Epic map05, and some of the dudes on the platforms became invisible when looking at them from near the starting area. Never noticed this in GL.

The limit is 8192 units, caused by the following in R_ProjectSprite

// too far off the side?
if (abs(tx)>(tz<<2))
  return;

tz is the projected distance of the sprite from the camera along the view vector. 8192=2^13 units in fixed_t is 2^13*2^16=2^29 as an int. So the shift up by two (i.e. multiply by four) takes it to 2^31, and you get integer wrap. So when tz > 8192*FRACUNIT, (tz<<2) is negative, and a negative can't be greater than a positive (abs(x) is absolute value, always positive)

>Gez has replied (show reply)

Without clicking on the notification I expect I've been beaten to the explanation, but submitting anyway.

39 minutes ago, galileo31dos01 said:

Could you post a picture please? I always use software mode and that's something I've never noticed.

Sure! Here's the spot where the Pinkies are visible:

Take a few steps back, and they're gone!

Edit: Interestingly enough, checking the builder shows a distance of around 5.5k units where this happens.

@Spectre01 I do not seem to be able to reproduce this in latest pr+ svn. I'm further away here and the demons are still visible

I'm using version 2.5.1.4 and definitely can't see them from the railway tracks on my end. Interesting.

Purposefully ignoring the drawing of far away sprites can improve performance massively, especially when there's tons of corpses to render. Even though it only needs to render a small handful of pixels, the setup time for each sprite adds up. So, maybe there's a setting that allows you to turn off distant sprites?

What I do know is that, if you look to the far right of that last picture, you can see an imp on a high ledge, and some fireballs, which look much further away than the pinkies, to me.

Dunno if this is related, but I used to be able to get screenshots with most (all?) of the monsters removed when playing really highly populated maps (e.g. Nuts). Meanwhile, in the game I never saw them disappear.

2 hours ago, Memfis said:

Dunno if this is related, but I used to be able to get screenshots with most (all?) of the monsters removed when playing really highly populated maps (e.g. Nuts). Meanwhile, in the game I never saw them disappear.

with prt-scr or the engine's built in screenshot thing?

The engine's.

Icon of Sin's attack rate is halved on skills 1 and 2.

3 hours ago, Alfonzo said:

Icon of Sin's attack rate is halved on skills 1 and 2.

Also on UV there are two spawn cube launchers (iirc).

^ No, there are not.

On 07/12/2017 at 0:33 AM, Spectre01 said:

I'm using version 2.5.1.4 and definitely can't see them from the railway tracks on my end. Interesting.

Mystery solved! Turns out since 2.5.1.4 there was a fix applied relevant to sprite drawing in r4516/r4518. Going back to before that point reproduced your observation.

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r4516 | entryway | 2017-03-04 15:53:52 +0000 (Sat, 04 Mar 2017) | 6 lines

Fixed sprites dissapering on ludicrm.wad map03 because of integer overwlow in clipping code (floor height is 31656).

Replaced with ZDoom code which is more coorrect I hope

https://www.doomworld.com/vb/post/1723386

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r4517 | entryway | 2017-03-04 16:33:12 +0000 (Sat, 04 Mar 2017) | 2 lines

rever r4516

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r4518 | entryway | 2017-03-04 18:44:16 +0000 (Sat, 04 Mar 2017) | 6 lines

Another try to fix sprites dissapearing on ludicrm.wad map03 in software mode.

r4516 failed at non 4x3 aspects

Also I noticed that old code don't draw many tall red firesticks on start position on sunder.wad map10 (240 sprites instead of 400+)

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2 hours ago, scifista42 said:

^ No, there are not.

Heh I guess I didn't recall correctly. Maybe it was one of the Final Doom episodes. I distinctly remember seeing two of them in a map30 somewhere.

Hell Revealed 2 had 3 or 4 of them, I believe.

From wads I have to hand, boss spawners (type 89) which appear in single player on UV:

1   doom2.wad      MAP30
1   plutonia.wad   MAP30
1   tnt.wad        MAP30
1   300minvr.wad   MAP30
1   av.wad         MAP30
1   epic2.wad      MAP30
1   freedoom2.wad  MAP30
1   hr.wad         MAP32
1   mm.wad         MAP30
2   d2ino.wad      MAP30
2   jenesis.wad    MAP28
2   mm2.wad        MAP30
2   perdgate.wad   MAP30
2   pl2.wad        MAP30
2   requiem.wad    MAP23
2   requiem.wad    MAP30
3   cchest3.wad    MAP29
4   200minvr.wad   MAP30
4   cchest3.wad    MAP30
4   hr.wad         MAP30
4   jenesis.wad    MAP30
4   ksutra.wad     MAP30
5   1994tu.wad     MAP30
6   pl2.wad        MAP32
9   cchest2.wad    MAP30
9   hr2final.wad   MAP30
40  sodfinal.wad   MAP30

@Megalyth Despite the above count, you are correct: plutonia has two, but the second is flagged absent in single player.

Wow, 40 in SoD. That must be insane. I never finished that set, I think I made it to map19.

sod30 is actually my favourite spawner map ever; its fantastic

The best spawner map is clearly Experiencing Nirvana's. 

8 hours ago, RjY said:

Mystery solved! Turns out since 2.5.1.4 there was a fix applied relevant to sprite drawing in r4516/r4518. Going back to before that point reproduced your observation.

Wow - good to know. That's for finding that. It's yet another Doom renderer bug caused by integer overflow!

7 hours ago, RjY said:

From wads I have to hand, boss spawners (type 89) which appear in single player on UV:

what, no mock 2

Icon of Sin's cube shooter uses the SS soldier's sprites, it's just invisible. Doom was secretly antifascist all along.

DSPDIEHI, the sound the player make when he's brought to -50 health by the killing blow(super death) was not featured in Doom. I guess it was added to Doom II after the introduction of the new bestiary of mid-tier monsters, which could more easily trigger that death scream.

13 hours ago, Uni said:

DSPDIEHI, the sound the player make when he's brought to -50 health by the killing blow(super death) was not featured in Doom. I guess it was added to Doom II after the introduction of the new bestiary of mid-tier monsters, which could more easily trigger that death scream.

Actually as far as I'm aware it's only the shareware version that is missing it.

DooM is epic!

All the SNES DOOM Oddities in CacodemonTube's channel. https://www.youtube.com/user/Cacodemontube/videos

in the doom press release beta, the earth in the one sky is different on the flat compared to the texture itself. adding it onto the texture itself:

going to assume this was to make the earth more visible on the flat so you knew what you were grabbing, but i kind of like it this way. seems a little more reasonable

MAP01 of 1monster.wad has a small nook on the west wall in the starting room (the metal wall with the yellow light to the left of you when you first start the level), holding a shotgun in a skybox. Never noticed until now.

I was watching the Evolution of the WAD series on YT and found out, for the first time in my 21 years of playing Doom, that the "leaky" rad suit is a thing.

Doom 3DO, this guy just jumped over that window, where you are supposed to flip the hidden switch to open a wall nearby.

At exactly 8:15 https://www.youtube.com/watch?v=wdTc0u565RE&t=495s

I confirmed it on a 3DO emulator. It took only a few tries. Not sure if it's because of the skippy framerate or player speed being different. Forward running, no strafe.

I'd think if it was a mistake, it would be impossible to get out and the player is stuck outside. But the other side opens like a normal door. Did they predicted the player could do that?

Then I tried on PC in GZDoom. Can't do it! Normal, strafe, even idkfa to try some rocket wall jumping. But if you idclip outside, the outside is opened like a door again.

I really flipped my senses, watching casually these guys playing Doom 3DO, and that guy just doing that. I am wondering if this also happens with Jaguar Doom or any other ports.