Extra content in Vanilla Doom?

[Ani]

I'm not working on anything exactly, this is just something that popped into my mind out of curiosity. Is it possible to add extra monsters or other entities in vanilla Doom? I'm well aware you can add a whole library of things in GZDoom based wads but since I found out about what was different between GZDoom and Vanilla Doom wads and how they're different from one another, it made me wonder if there's some sort of limit on how much content you can add. One time I looked into Doom 64 for Doom 2 and I discovered the Wolf SS, Commander Keen and Spider-Mastermind were all replaced with the two nightmare monsters and the MotherDemon. I was disappoint neither of the 3 got to share the spotlight in a really good megawad. 

 

Another time, I looked into TNT and Plutonia and discovered the only things that were added were new textures. So is adding new things just exclusive to textures? Is there some complex process to go through in your wad besides making decorate and script coding? Feel free to answer. I'd love some insight.

[Doomy__Doom]

16 minutes ago, Ani said:

I'd love some insight.

https://doomwiki.org/wiki/DeHackEd

[ViolentBeetle]

Vanilla doom would only let you replace stuff, so you can sacrfice some decorations to add new monsters. New procedures also can't be created, so you can't really create new attacks, but you remix existing ones (Like, for example, make an enemy that fires all 3 mancubus patterns and a stream of imp fireballs all at once) and alter existing projectiles stats.

[Ani]

6 hours ago, ViolentBeetle said:

 

What about extra textures? Or do you gotta sacrifice that too?

[ViolentBeetle]

3 minutes ago, Ani said:

What about extra textures? Or do you gotta sacrifice that too?

No, you can add them freely. There's probably a limit related to acceptable size, I'm sure. It's probably high.

However switch pairs and animation loops (Specifically first and last frame names) are both hardcoded, so you can only replace.

[Foxpup]

1 hour ago, ViolentBeetle said:

However switch pairs and animation loops (Specifically first and last frame names) are both hardcoded, so you can only replace.

For switches, you can just make the existing textures wider, put new switches in the resulting space so that the altered texture looks like a horizontal row of different switches, then use texture offsets to select which switch actually appears in the map.

 

Animations are harder, but you can exploit the fact that the engine defines a few animations that aren't used in all games. For example, the wall animations BLODGR1-BLODGR4 and SLADRIP1-SLADRIP3 are only used in Doom 1, not Doom 2, but will work in Doom 2 if you add textures for them, thus they can be used for custom animations.

 

Final Doom used both of these tricks to add its new switches and animations; the executable wasn't modified to accommodate this.

[Doomkid]

Just to add onto what Foxpup is saying, the 4 flats SWATER1 - SWATER4 were planned, but never included, however these names can be used to add a new animating FLAT as well as the ones mentioned above for new animated textures. So handy!

[Individualised]

22 minutes ago, Doomkid said:

Just to add onto what Foxpup is saying, the 4 flats SWATER1 - SWATER4 were planned, but never included, however these names can be used to add a new animating FLAT as well as the ones mentioned above for new animated textures. So handy!

Speaking of - do the animated "horizontal" doors still exist in the retail Doom 2 executables or were they only in one of the prototypes?

[Ani]

3 hours ago, ViolentBeetle said:

 

I wonder what those texture limits are to make sure you don't exceed that boundary and create some problems.