Modding

From modwiki

General information that is helpful on getting started with, producing and distributing Doom 3 engine mods.

Contents 1 What is a mod? 2 Game basics 2.1 Installing the Game 2.2 Where to place what 2.3 Starting it up 3 Changing the game 3.1 Categories of Game Design 3.2 Getting started already 3.3 Got questions 4 Distribution 4.1 Putting it all Together 4.1.1 Creating compressed media files 4.2 Addon paks 4.2.1 Packing your assets 4.3 Creating Install Files 4.4 Uploading your Creation

What is a mod?

Mods (short for modification) are made by the general public by building on and expanding the assets and mechanics of an existing game. They can include new items, weapons, characters, enemies, models, modes, textures, levels, and story lines. They can be used for the single-player or multiplayer part. Mods are generally seperated into three categories:

Paks 

Basicly a simple addon to the existing game, these mostly come in the form of level-, skin- and soundpacks.

Mods 

These are all the hybrid forms where only aspects of the game are modified, ranging from modified game mechanics to the addition of a new set of levels and skins.

Total conversions 

These aim at totally replacing the assets and mechanics of the source to create an entirely new game.

Game basics

Installing the Game

Before you start any editing, you should install the Doom 3 engine game of your choice into a directory with no spaces. (Eg: For Doom 3, the folder could be "d:\doom3" compared to "c:\program files\doom 3\) This avoids a few technical problems you would encounter otherwise. Also make sure to update it to the newest version available.

Where to place what

There are 3 types of folders in the game directory to place assets in:

base 

The game assets folder. All the PK4's of the retail game are in this folder. Only game updates and paks should be placed there, mods need their own folder.

expansion 

A folder reserved for expansion packs containing additional asssets.

mod 

Folders with various names containing everything needed to run the mod. Every modfolder is isolated so that no assets of one mod influence another. Mods can use the assets from the base or expansion folder.

The base folders can use a different name then just 'base'. Here is how they are called in different games:

Quake 4: 

/q4base

Prey: 

/base

Expansion folders for different games:

Doom 3: ROE: 

/d3xp

Starting it up

To start your mod, you could either start the game and use the "mods" selection in the main menu. (If present) However, you will often need start your mod to playtest it. Therefore it is easier to create a simple shortcut with a modified command line. Eg:

d:\doom3\doom3.exe +set fs_game mymod 

This starts Doom 3, with the mod folder set to "mymod". For further information, see Startup parameters.

Doom 3: ROE: 

If you are modding for the Doom 3: Resurrection of Evil expansion, add "+set fs_game_base d3xp" to the shortcut

Quake 4: 

Since there has been no announcement for expansion packs, the "expansion folder" feature can be used to use assets from the base folder and another mod folder.

Changing the game

Categories of Game Design

There are lots of aspects to game design, listed below with links to their own pages where you may find more information, tools, tips and tricks. They are basicly listed in order of difficulty.

Texturing 

Modifying the looks of the game by adding/changing materials

Audio design 

The creation of musical tracks and sound effects

Mapping 

Making new levels

Modelling 

Modelling and file format information

Declarations 

Changing the game's behaviour and content

Scripting 

Changing the game's actions

Coding 

Modification of the game's source code

Of course, modding a specific things (Eg. modifying weapons) needs experience from multiple categories. Use your common sense to find what you need, or go trough the game's assets to see what is used to make something. (See the Got Questions section below)

Getting started already

Once you read this, you should have made up your mind on what you want to do with the Doom 3 engine of your choice.

• If you want to make a mod, (Not a pak) you need to create a mod folder. It will serve as a place for all your assets and will make sure that your work stays seperate from mods. The folder's name will define the name of the mod. Allthough you can use your imagination for a mod's name, there are a few recommendations when making the mod folder:
  • It should not contain any spaces in the folder's name.
  • Try to keep the name lowercase. (Because Linux cares when using the fs_game parameter.)
  • Try a length of 4-10 characters.

Got questions

In case you get stuck somewhere or have some questions, it is a good idea to look at the content of the original game. To do this, you need to unpack the PK4 files contained in the base game directory. It is best to extract them to a seperate folder (eg: Doom3\basextract\ in case of Doom 3) so the resulting files do not conflict with the orignal content. (Called 'vanilla' content) Also note that you should extract them in alphanumeric order, starting with the lowest number to allow for more recently updated files to overwrite their older counterparts.

Beware that the unpacked assets of the game will be worth multiple gigabytes of diskspace. Make sure that you have enough free space or only extract parts.

If you still got questions after some research, try to search for help at specific forums like Doom3World.

Distribution

Once you have finished your mod you will want to distribute it. This section covers a few approaches to this. Also keep in mind that your means of distribution is usually the first thing the player sees of your game. Be sure to invest ample time into this as not to annoy the user with broken or overly complicated installs.

Putting it all Together

First you need to make sure that everything is in one place. If you are working in a mod-team, http://developer.valvesoftware.com/wiki/Making_a_MOD might be a good read on how to deal with the packaging.

Creating compressed media files

After you have all your assets in one place you will want to compress your media files so they take up less space. You can automatically generate a batch file to create compressed versions of TGA and WAV files. To do so you must follow these steps:

• Start the game, open the console.
• com_makingBuild 1
• image_useOfflineCompression 1
• startBuild
• map <mapname>
• finishBuild

You should now have two batch files present: makedds.bat and makeogg.bat. Start these from your mod containing the assets. Note: They must be left unpackaged untill after the compression. The compression step will not scan PK4 files.

Addon paks

Auto downloading is a feature of the Doom 3 engine where certain PK4 files don't need to be downloaded untill they are needed. These are called addon paks, and they need an extra configuration step.

See

• http://zerowing.idsoftware.com/linux/doom/AddonPaks
• http://www.iddevnet.com/quake4/AutoDownload

Packing your assets

You should pack all your custom files into PK4 files. It is important that you have an intact folder hierarchy within your PK4 files. As usual it helps to look at the original game assets if you have any questions. When you distribute your PK4 file with your mod or map you should make sure that the root directory in the pak file only contains the following files:

• addon.conf - See addon packs above
• description.txt - Optional text file for mod folder description (only needed for mods in seperate folders).
• binary.conf - This must be included if the PK4 contains compiled game code. Without binary.conf the Doom 3 engine will not load your modified binaries.
• mapname_readme.txt - Your readme file, if you choose to add one. It's generally a bad idea to just call this readme.txt as anyone extracting the pack contents may overwrite an already existing readme.txt file.

Creating Install Files

Short rundown of what an Install file does, list of free-, share- and payware software

Uploading your Creation

Short rundown of the upload process, links to a few free gaming file-storage areas