New to editing: Possible to use ACS and DECORATE support to Doom2 iwad?

Simply put: I love modifying games and I would like to go back and re-play Doom2 using custom DECORATE monsters and ACS scripts. How do I best achieve this?

I was able to load an ACS script using Slade3 and using a LOADACS lump, but what about DECORATE support? Can I jam some other kind of lump into the iwad so that DECORATE does start working? I also read that if you name a text file "DECORATE.WAD" (or behavior.wad, etc.) and add it to zdoom's launch parameters, it will interpret that text file as that kind of corresponding lump. Does this work even when using it for doom-format maps?

As a last resort I'm absolutely willing to convert the original doom2 iwad to UDMF, but I does such a converter exist? I found a few links to beta software from '09, but anything more recent?

Thanks!

Okay, first thing first: you should not modify the IWADs directly. You should load mods that are independent files.

If you just want to change monsters and stuff, look at gameplay mods. If you also want to change the levels themselves, you can copy them in a PWAD and edit them.

I guess I wasn't clear enough:

How can I add only gameplay mods to doom2 without changing the levels (decorate and acs support only)?

Thanks!

Generally, it is done by defining new content that replaces existing content. You have several mechanisms for that. Here is a good example. Here is another. A third, and a fourth.

Replacing players or weapons requires more work than replacing monsters. Adding ACS stuff also requires more work.

For documentation, read up on DECORATE, MAPINFO, and ACS libraries. Without knowing more precisely the kind of things you want to do, I can't help you more than tossing a bunch of links in your direction.
http://zdoom.org/wiki/MAPINFO
http://zdoom.org/wiki/DECORATE
http://zdoom.org/wiki/Creating_new_player_classes
http://zdoom.org/wiki/Creating_new_weapons
http://zdoom.org/wiki/Weapon_slots
http://zdoom.org/wiki/Creating_new_monsters_or_other_complex_items
http://zdoom.org/wiki/Improving_original_monsters_with_DECORATE
http://zdoom.org/wiki/RandomSpawner
http://zdoom.org/wiki/ACS
http://zdoom.org/wiki/Libraries
http://zdoom.org/wiki/Using_ACS_in_Doom-format_maps

Thank you for that very detailed reply.

I've got a compiled .o ACS file which I compiled and wrote myself (tested working). How can I run that ACS script in vanilla doom2, without adding additional levels? The way I've currently done it is to modify the original iwad (making a backup) and then inserting A_START, A_END, and import the .o file between (useing Slade3). Then I call the library name using LOADACS. And it works fine this way.

But how do I do it without modifying the maps of the original iwad (or the main iwad itself)?

Also how would I pull the same feature for using DECORATE? Say I wanted to add a DECORATE monster (not overriding an original monster?)

The only thing I've figured out so far is what I just described in order to get ACS working without changing any maps.

Also, I've not gone through the source of some of those links yet, so forgive me if the answer is there. Also, I'm quite well versed in the ACS wiki, I just couldn't find an answer there.

Also, if it makes a difference, I've got a lot of programming background, so the "difficulty" of decorate or acs doesn't scare me. I've made slopes, sideways opening doors, my own custom monsters, friendly bots, but all of this was using UDMF format, I don't know how to add these things to original doom levels.

Rephrase of question:
How can I get the _most_ extra modding support out of the original doom2 maps?

MALON said:

Rephrase of question:
How can I get the _most_ extra modding support out of the original doom2 maps?

If you had looked at those mods linked to by Gez, then you would have found out, that none of them have maps in them or modify the original DOOM2 maps.

Okay, strictly speaking, that is not quite correct.
Terror does introduce a titlemap, but the rest holds true.

As to modifying the DOOM2.IWAD, of course, that is up to you. You are the master of your own domain. Do yourself a favour though, have the original at least set to 'Read Only'. And a couple of copies stashed away somewhere safe.

MALON said:

I've got a compiled .o ACS file which I compiled and wrote myself (tested working). How can I run that ACS script in vanilla doom2, without adding additional levels? The way I've currently done it is to modify the original iwad (making a backup) and then inserting A_START, A_END, and import the .o file between (useing Slade3). Then I call the library name using LOADACS. And it works fine this way.

But how do I do it without modifying the maps of the original iwad (or the main iwad itself)?

See, here, you didn't actually modify the maps, did you? All you did was add some lumps to the IWAD, without changing the maps. In fact, you changed nothing from the original resources in the IWAD, you only added some extra stuff.

If, instead, you put the A_START, library, A_END, and LOADACS lumps in a PWAD that contains nothing else, and load that as a mod with an unmodified IWAD, you'd get exactly the same result. It would work just as well.