Programming Unreal Tournament

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Programming Unreal Tournament

• Joe Manojlovich (josephm_at_sis.pitt.edu)
• University of Pittsburgh
• School of Information Sciences

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Points of Contact

• Usability Study Lab, 2nd floor, Information
  Sciences Building
• Meetings every Tuesday, Thursday 3pm to 7pm (all
  are welcome)
• (Unofficial) Pittsburgh Unreal Research Group
• There is a surprisingly large amount of UT
  hacking for research purposes going on in the
  Pittsburgh area
• University of Pittsburgh (several schools)
• Carnegie Mellon University (several schools)

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What is Unreal Tournament?

• UT is a multiplayer video game
• Produced by Epic games (http//www.epicgames.com)
• Runs on Windows, Linux, Macintosh, PlayStation,
  and soon Xbox
• http//www.unrealtournament.com

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Old/Current Versions of Unreal

• Unreal I
• The original Unreal game
• Single player
• Obsolete and unsold now (?)
• Unreal Tournament
• Multiplayer Unreal game
• Obsolete and unsold as of a month or 2 ago

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New Versions of Unreal

• Unreal 2
• Single player
• Due 2003
• Unreal Tournament 2003
• Multiplayer
• Due summer 2002 (any day now)
• Unreal Forever
• Xbox
• Due 2003

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Why Program UT?

• By using UT as a basis for other research, you
  can avoid needless reinventing while benefiting
  from a proven development platform
• UT is designed for programming, and many tools
  and resources are available to assist you

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Research Being Done with UT

• Gamebots
• This is a modification to UT that allows one to
  control UT bots remotely over a standard network
  connection (www.gamebots.org)
• CaveUT
• This project uses multiple UT clients to create
• el-cheapo 3D visualization (http//www2.sis.pitt.
  edu/jacobson/ut/CaveUT.html)
• Many others

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How to Program Unreal Tournament

• UnrealScript
• Source code level
• Level Programming
• Graphics level
• Scenes
• People
• Weapons

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UT Source Code

• Since UT is based on a virtual machine model like
  Java, most of the game is actually written in
  UnrealScript
• You can read the source code to most of the game,
  except the low level graphics rendering
  components and a few other bits
• UnrealEd will let you browse and edit the game
  source code
• Also available online http//usl.sis.pitt.edu/tru
  rl/unrealdocs

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Common Terms

• Bots Players in game under human or AI control
• Level self-contained environment containing
  bots and their surroundings
• Maps a level, without the bots
• Game a level, with active bots, running on a UT
  server

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Types of Games

• DeathMatch
• Free for all

• TeamGame
• Team free for all

• Domination
• Control of
• level points

• Assault
• Task-oriented

• Capture the Flag
• Goal of returning
• enemy flag to
• home base

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The Unreal Virtual Machine

• UT is divided up into several components
• Server
• Client
• Rendering engine
• Engine support code

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The Unreal Virtual Machine
Actor(s)
Tournament Male
Level
DM-Tutorial
Game Type
Death Match
Client(s)
Game Code
Engine
Network
OpenGL, DirectX, etc.
Underlying Hardware/Operating System
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Unreal Network Architecture
UT is a client/server based game
Client
Server

• Currently supports 32 players on a server
• This may increase with the new version of UT

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Java/C vs. UT

• If you have some knowledge of any object-oriented
  language, then learning UnrealScript itself is
  easy
• UnrealScript is much simpler than real
  object-oriented languages which are burdened with
  complex features unnecessary for game development

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Object-Oriented Programming

• Objects
• Function code and data combined in one unit
• Classes
• Templates for production of objects
• Inheritance
• Classes arranged in a hierarchy, where children
  classes start with properties of its parents

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Inheritance

• Animal
• Reproduces
• Consumes

• Bird
• Has Wings
• Flies

• Fish
• Has Fins
• Swims
• Gills to Breath

• Robin
• Small
• Red Chest

• Ostrich
• Large
• Doesnt Fly

• Great White
• Large

• Goldfish
• Small

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Class Structure in UT

• Objects/Actors
• Pawns
• Info

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Object/Actor Classes

• Object is the basic superclass for every Unreal
  class
• Actor class, subclass of Object, defines basic
  game functionality
• Players
• Weapons
• AI
• Most of the UT game itself

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Pawn Class

• Subclass of Actor
• Defines the living entities of a level
• PlayerPawn, a subclass of Pawn, is used for all
  players in the game
• ScriptedPawn, another subclass of Pawn, is used
  to drive the built-in game players

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Info Class

• Info classes maintain game data
• GameInfo manages game related information
• ZoneInfo handles the composition of spaces in
  levels, such as water, lava, etc.
• PlayerReplicationInfo is used for network games,
  to minimize network traffic between Unreal
  clients and the server

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UnrealScript Syntax

• UnrealScript is a full programming language
  solely used for the Unreal series of video games
• Most of its syntax is very similar to other
  high-level programming languages such as Java or
  C

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Variables

• byte A single-byte value ranging from 0 to 255.
• int A 32-bit integer value
• bool A boolean value either "true" or "false"
• float A 32-bit floating point number
• string A string of characters
• name The name of an item in Unreal (such as the
  name of a function, state, class, etc)

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Variables (cont.)

• Enumeration A variable that can take on one of
  several predefined name values
• Object and actor references A variable that
  refers to another object or actor in the world
• Structs Similar to C structures, UnrealScript
  structs let you create new variable types that
  contain sub-variables

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Variables (cont.)

• To declare a variable
• var int a
• var byte Table64
• var string32 PlayerName
• var actor Other

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Language Constructs

• UT supports all the standard loops, like those in
  Java or C
• If
• For
• While
• Do-While

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UnrealScript States

• States are unique to game programming languages
  like UnrealScript
• Allow one to define functionality based time and
  state of a bot
• For example, a bot could have a Running state
  that will cause the bot to flip while jumping,
  but only while running, and not while standing
  still or walking

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An Example State
auto state Idle Begin log( "I am idle!"
) sleep( 10 ) goto 'Begin'
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An Example State (cont.)

• All this state does is override a built-in
  inherited state that is active when a bot isnt
  doing anything, i.e., idle
• Every 10 seconds of idle time, this code will
  print to the log I am idle!

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Modifications

• Mutators
• Used to make slight changes to the game
• Subclass parts of the game, and redefine game
  code
• Can be mixed with other mutators at run-time
• Gametypes
• Used to change large parts of the game
• Cannot combine with other gametypes

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Using the Command Line Tools
Start-gtPrograms-gtAccessories-gtCommand Prompt
cd C\UnrealTournament\System
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An Example Mutator

• Remember that mutators simply take some built-in
  functionality of UT and modify it slightly
• Mutators subclass the UT Mutator class
• For this example, well create a low gravity
  mutator. The game already has one built in, but
  it makes a good example, as its very simple.

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The Low Grav Mutator

• In the UnrealTournament directory, create a
  directory named MyPackage and inside that a
  directory named Classes
• Create a text file named LowGrav.uc in the
  Classes directory
• Edit the UnrealTournament.ini file, in the System
  directory, and add your package name to the
  EditPackages list

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The Low Grav Mutator (cont.)

• class LowGrav expands Mutator
• Each source file will have this class
  declaration, and only one class can be in each
  source file

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The Low Grav Mutator (cont.)

• function bool CheckReplacement(Actor Other, out
  byte bSuperRelevant)
• if( Other.IsA('ZoneInfo'))
• ZoneInfo(Other).ZoneGravity
  vect(0,0,-200)
• return true
• An inherited function, used to replace or modify
  actors in a level

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The Low Grav Mutator (cont.)

• In the command prompt, enter the
  UnrealTournament/System directory
• Type ucc make all
• Create a text file named MyPackage.int in this
  directory, with the contents (one line)
  Object(NameMyPackage.LowGrav,ClassClass,
• MetaClassEngine.Mutator,DescriptionMy Low
  Gravity, My Low Gravity")
• This will make your mutator show up in the game
  menus

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The Low Grav Mutator (cont.)

• To run your mutator, start UT
• Start a new practice session
• Click on the Mutators button
• Scroll down to My Low Gravity and double click
  on it
• Close the window, and start the practice session

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UnrealEd

• UT comes with a dedicated 3D level modeling and
  source code editing program
• Most do actual coding outside of UnrealEd, since
  many prefer to use other source code development
  tools such as Microsoft Developer Studio
• Most source code work done by UnrealEd can also
  be done from the command line

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Using UnrealEd

• Start program UnrealEd.exe in the
  UnrealTournament/System directory
• Most people design maps in more mature 3D
  modeling program, such as Maya or 3D Studio Max
• UnrealEd is fine for doing pure UT design that is
  not too complex

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An Example Level

• I was planning to show an example of creating a
  level here, using UnrealEd, but its not
  something that lends itself well to a
  presentation
• This is also a cheap way for me to get out of
  admitting that I dont know much about level
  programming

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Unreal Graphics

• Meshes
• These are the skeletons that form the bodies of
  UT creatures
• Have no defined surface
• Textures
• Applied to meshes to provide a surfaces

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Resources

• http//unreal.epicgames.com
• http//www.planetunreal.com
• http//www.unrealscript.com

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Questions

• Questions, concerns, comments, sarcasm, insults?
• Please email or come to the group meetings on
  Tuesdays and Thursdays there are just so many
  little tips and tricks that are best learned in
  person