Introduction to modding

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Introduction to modding

Creating or modding a game is like writing a theater play: in both cases, you have stages, actors, scripts, and music. A level is built so that when the player performs certain actions or reaches certain locations, further events are set in motion. The player is told what to do through various textual instructions, voice acting, and cinematics (cutscenes).

Modding can be an intimidating field to get into, but taking things one step at a time, you can learn a lot about how to make games. Like learning a second language, modding your first game is always the hardest, and then you learn the common points that games share and you can more easily pick up new ones. Additionally, there are lots of different ways for someone to mod; whether your talent is art, sound, modeling or design in general, there's something for you to do, and collaborating with others to divide the work according to your abilities can lead to a memorable, rewarding creative experience. Because of the DIY nature of our work here, it's recommended that you have an interest in, or at least a high tolerance for, technical details. We do not yet have any modding solutions with a big red button that says "easy".

Introduction to the engine

Oni runs on an engine that was custom-written for the game. At the time development started, Bungie did not yet have a true 3D engine, and it appears that the lead coders intended their work to be reused in future Bungie titles. In the course of events, this never happened. However, as a result of this advance planning, the Oni engine (which does not have a name per se) is built in an industrial, abstracted way in two major layers: (1) the BungieFrameWork (BFW), which contains general code for things like 3D graphics and scripting, and (2) the code for Oni itself, which adds stuff like the AI and the combat system.

Due the non-existence of modding tools at the time of Oni’s release, fans had to tame the wild jungle of raw game data and create modding tools on their own. It took over seven years to unlock most possibilities –- and the work is still ongoing. Read the full story HERE. The short version is that we can now mod almost all types of data effectively, meaning we can create entirely new levels with new characters, new scripts, new voice acting, and new music. Now we're turning our focus to making tools that are user-friendly so artists can work unimpeded.

Altogether, we have identified 124 types of resources in the game data, however only about 88 (and a half) are used. It may sound intimidating at first, but many of the data types (often called "file types" on this wiki, and "tags" in many other game modding communities) fold into each other, such that you only need to know a few file types well, and the rest are created for you. Depending on the kind of modding you want to do, you might be able to start modding with only a little knowledge of the engine.

Kinds of modding

Scripting

The easiest kind of modding is scripting. Scripts are written in the BungieFrameWork Scripting Language and stored as plain-text files with the suffix .bsl, so we often refer to scripts as "BSL mods". Scripts take a lifeless level and spawn characters in it (the AI-driven NPCs and Konoko), give the level a logical flow of events, make the AIs play certain roles, drive cutscenes, and alter the level's appearance.

Scripting is the easiest way to mod because you can work with existing game data, and only have to modify BSL files using a text editor. It's quick and easy to see the results of your work (just reload the level), and you have lots of accessible examples to learn from (14 levels' worth!). That being said, scripts constantly reference game resources in sometimes technical ways, so you will have to learn how certain data types work in order to script effectively.

Go HERE to start learning about scripting.

Binary modding

This is where those 88 data types come into play that we mentioned earlier. Broadly speaking, the kinds of data we're talking about are: level geometry (architecture, triggers, and furniture), characters (class data, models), text (diary, objectives, subtitles, etc.), music, voice-overs, and sound effects. However, new levels do not require all this data to be made from scratch. You might decide to re-use a level or some of its resources, or make a new level populated with existing characters, etc.

The game data is called "binary data" because it's made of raw 0s and 1s until our tools make it into something more modder-friendly. The basic process of modding game data involves breaking the level data (a .dat file supplemented by a .raw file and also a .sep file on the Mac) into its component resources (.oni files), then converting those resources into something editable. What that editable format is depends on the kind of data you're editing. It might be plain text, XML, PNG, DAE, WAV, etc.

Thus, besides our community modding tools, the program(s) you need in order to mod will vary according to your modding task; you might need nothing more than a text editor, you might need a free bitmap editor, or you might need a full 3D modeling package. Thankfully, since Oni is graphically primitive, you won't need to know as much about modeling as with a modern game, and there are free modelers available (but not as good as the commercial ones).

In any case, make sure you download the Anniversary Edition, which provides a modding framework and installs modding tools. Go HERE to start learning about the binary data or continue reading to learn a little more about specific types of binary modding.

Characters

Characters in Oni are built with a simple 19-part skeleton. Talk about ONCCs and related data here. Mention Mod Tool, Blender, Gimp, Paint.NET.

Animations

An "appetizer screenshot".

Talk about OBANs and TRAMs here. Mention Mod Tool and Blender.

Levels

Script commands are useless when their addressed resources don't exist. Talk about AKEVs and related data here. Mention Mod Tool, SketchUp, and Blender.

Tools, documentations and tutorials

BSL

• introduction and database links HERE
• tutorials: BSL:Tutorial/Scratch

OBD

file converting in general

• tool download: OniSplit
  • tool download: AETools - GUI for Macintosh
  • tool download: OniSplit GUI for Windows
  • tutorial: basics

3D

• tool tutorial: Blender
• tool download: (formerly "XSI") Mod Tool
  • more information about Mod Tool
  • obj export requires an addon
• tool tutorial: OCF's XSI thread
• tool download: SketchUp
• tutorial: Importing character models TRBS
• tutorial: AE:Importing_weapon_models
• tutorial: SketchUp

Animation

• tool download: (formerly "XSI") Mod Tool

You need to add some stuff to that file to make it actually work as an animation. In particular the animation type, from/to states and varient needs to be set.

For all I know this works with animations exported from Oni and modified in Softimage. If you come up with a completly new animation it should work as long as the skeleton is similar to the one used in Oni.

Note that the geometry that is present inside the Collada file is used to compute the "vertical extents" so it better be the same or close to the one the animation is intended for.

The biggest problem are the attacks. While it's not difficult to add attacks to the xml file, computing the necessary "extents" is not going to be easy. I guess in the end I'll have to add some command to OniSplit to do it.

Edit: attack extents becomes automatically calculated with onisplit v0.9.55.0 and newer

• tutorial: AE:Authoring_custom_camera_animations

HEX

• any hex editor
• tool download: OniUnPacker
  • tutorial: tweak animation
• tutorial: Adding spawnable characters to a level CHAR
• tutorial: Adding character classes ONCC

Sound

• Instructions how to import sounds and links to conversion tools can be found HERE.

Textures

• tool download: gimp
• tutorial: Modifying textures TXMP

Need some inspiration?

Play some existing mods to get ideas (which you can install with the AE), or look at the pages below.

• Modding Brainstorms
• Review criticisms
• AE:Requests