More Doom oddities

[General Rainbow Bacon]

@printz: I remember that I usually got stuck in an infinite downward platform in Doom 2 map 17, at this platform:



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*The one to the right of the Pain Elemental*

[Maes]

Regarding Doom's map coord system, I never realized it can actually wrap around.

@GoatLord: what you saw looked anything like that?



I made a test level where you start off in a small room placed as south and as far to the left as DoomBuilder will let me, and has identical, unconnected rooms placed to the far north and to the far right. The decoration serves to orient the player on the direction to take (one pole = east, three poles = west, corpse hanging from one leg = south etc.)

If you idspispopd or idclip and go further south or west, you will discover that you just wrap around and re-enter the map from the top or far east, eventually entering one of the "northern" or "eastern" rooms (unfortunately, the automap is almost useless on a map with this extension, that's why it's important to "set a course" from the starting room).

Unfortunately, I discovered that even placing THINGS near tha map extremes causes weird overflow and crashes (e.g. adding some armor bonuses to the north of the map caused a status bar DrawNum crash :-S)

The visuals with such distances get weird, including screen-wide visplanes and ultra-stretched walls.

In making it, I also discovered that DoomBuilder will overflow and crash if there's more than 40K or so diffence between the map's extremes (if I try placing single lines or vertexes) or will refuse to paste a copied sector under these conditions.

I wonder if, with manipulating the map's structures, it wouldn't be possible to build a level that infinitely loops onto itself without the use of teleporters in vanilla Doom.

[Koko Ricky]

Maes, ah yes, this is very much like what I saw! I remember thinking it was really something back in the day.

[General Rainbow Bacon]

A wrapping level would be really cool if possible. Seeing as when you noclip you just go out into uncreated mass, someone could create a whole world if they used zdoom, and have other levels be inside areas.

[Maes]

The only way to test that would be with a specially generated level, and also determine if it's possible to have actual linedefs that can cross the map boundaries and join with vertexes "from the other side".

From my understanding, Doom inteprets linedefs as vertex pairs, and the direction vector is always considered to be from the smallest coordinate to the largest, and never viceversa, or else pairs would be ambiguous, so it would not be possible to have linedefs getting connected "over the boundaries".

[neubejiita]

The blockmap is screwed up with a infinite wrapping level, I made one for Zdoom ages ago that had a 32768 long corridor that was wrapping, but the monsters and player could walk through the walls without any problems. You would need to create a modification to the Doom engine to handle such a large world. And I had to create the corridor in many sections joined together rather than one long sector.

http://bejiitaswrath.com/maps/e3m5bug.jpeg

And here is a screenshot of the E3M5 lindedef. Pretty destructive when activated.

My Zdoom infinite wrap wad. Doom2 MAP32. Enjoy.

http://bejiitaswrath.com/maps/wrap.rar

[Devalaous]

neubejiita said:

The blockmap is screwed up with a infinite wrapping level, I made one for Zdoom ages ago that had a 32768 long corridor that was wrapping, but the monsters and player could walk through the walls without any problems. You would need to create a modification to the Doom engine to handle such a large world. And I had to create the corridor in many sections joined together rather than one long sector.

http://bejiitaswrath.com/maps/e3m5bug.jpeg

And here is a screenshot of the E3M5 lindedef. Pretty destructive when activated.

I guess whatever bug it causes is fixed in ZDoom? I was looking for this stuff earlier and found nothing out of the ordinary...aside from being able to activate those walls. Unless it does something else.

[neubejiita]

Ragnor said:

I guess whatever bug it causes is fixed in ZDoom? I was looking for this stuff earlier and found nothing out of the ordinary...aside from being able to activate those walls. Unless it does something else.

Works perfectly with Prboom+ in -complevel 2, but not with normal complevel.

[neubejiita]

GoatLord said:

Now, I'm no expert on linedefs and whatnot, but here's a couple things I noticed:

- In PSX Final Doom, the level Ballistix has a secret exit which is impossible to reach. I obsessed with it for awhile because the game claimed there were over 30 maps, although if you perform a level select cheat there are indeed only 30 maps. I'm not familiar with PC Final Doom, so I imagine there was originally a secret exit whose path was removed for the Playstation version, but you can still see the exit.

That is an exit for deathmatch multiplayer modes.

[Grazza]

neubejiita said:

Can anyone please tell me where the E3M5 linedef is? I am looking with Doom Builder 2 and I cannot find it.

Doom Builder never detected invalid tags as far as I know (and even encouraged people to make this error), which was partly responsible for the number of maps made with this Zdoomism. Use Wad Author's error checking and you'll find them easily.

Ragnor said:

I guess whatever bug it causes is fixed in ZDoom?

It's not an engine bug - it's a map error.

Certain linedef actions require a tag for both the linedef that triggers it and the sector to which it applies. This tells the engine what activates what. If there is no tag, then the engine doesn't know what to apply it to.

In vanilla, it applies it to all sectors with no tag. Presumably id's programmers didn't anticipate anyone would make this error, and so didn't make any provision for it.

In Boom, it applies it to no sectors at all.

In Zdoom, it applies it an adjacent sector, if this makes sense.

Obviously, in Prboom(+), the way it behaves depends on what you've asked it to behave like. If you've asked it to behave like vanilla, that's how it will work, etc. In Prboom+, there is a "compatibility with common mapping errors" option, which will cause it to behave like Zdoom. This only applies if the complevel is Boom or greater, and you are not recording and playing back a demo.