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Games Programming with Java
240-492, Special Topics in Comp. Eng. II
Semester 1, 2002-2003
1. Motivation and
Background
 Objective
– to motivate this course by giving some
background on games programming in Java
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Overview
1.
2.
3.
4.
5.
The Games Market
Wrong Ideas about Java for Games
Some Commercial Games Using Java
Why use Java for Games?
Java Compared to C
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6.
7.
8.
Evaluating Java for Game
Development
The Java Games Profile
Game Engines
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1. The Games Market
 US
video game sales increased by 43% from
$6.6 billion in 2000, to $9.4 billion in 2001.
 “Grand
Theft Auto 3” for the Playstation 2
sold 2 million units between October 2001
and January 2002.
 The
online gaming market will probably be
worth $1.1 billion by 2003.
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1.1. Game Types
These types are used at
http://www.arcadepod.com/java/
for available Java Games (~700)
 3D
Games
 Multi-Player
 Action
– Fighting, Scroller, Shooting
 Classic
– Arkanoid, Asteroids, Invaders, Lander,
MineSweeper, Pacman, Pinball, Pipeline, Pong,
Tetris, Worms
 Adventure
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 Indoor
Sports
– Billiards, Bowling, Darts
 Board
– Backgammon, Battleship, Checker, Chess,
Connect 4, Crosswords, Go, Mahjong, Othello,
Tic Tac Toe, Yahtzee
 Outdoor
Sports
– Baseball, Basketball, Football, Golf, Hockey,
Racing, Soccer, Tennis, Water Sports, Winter
Sports, Street Sports
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 Card
I’ve excluded
the General and
Miscellaneous
subcategories
– Solitaire, Spade
 Mind
– Concentration, Mazes, Puzzle, Strategy, Trivia
 Casino
– Baccarat, BlackJack, Craps, Poker, Roulette,
Slots
 Educational
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1.2. Which Games to Build?
 You
should read:
How do I Make Games? A Path to Game
Development
Geoff Howland
http://www.lupinegames.com/articles/
path_to_dev.html
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 He
identifies four games that programmers
should implement in order to learn games
techniques:
– Tetris, Breakout, Pacman, and a side scroller
such as Super Mario Brothers
I
have included links to examples of these
games with source code in:
/Java Games/Background/learnGames.txt
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 In
this part of the course, we will be
learning techniques based around:
–
–
–
–
an arcade-style game (“Alien Attack”)
an isometric arcade-style game (“Alien Tiles”)
a networked Chat system
a networked Tic-Tac-Toe
 So
looking at these other games would be
very useful to you.
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2. Wrong Ideas about Java for Games
 No
one writes serious games in Java.
 The
Java platform is too big/slow for
games.
 Sun
isn’t doing anything about the games
market.
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3. Some Commercial Games Using Java
 Vampire
– scripted in Java
 Shadow
Watch – pure Java
 Who
Wants to be a Millionaire and
You Don’t Know Jack – all logic in Java
 Majestic
– back-end is pure Java
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 Star
Wars Galaxies – scripted in Java
 Skies
of Arcadia and Daytona USA
– Sega Dreamcast games containing a JVM
 Jamid
(a Quake clone) and
F1 Gran Prix – both use Java3D
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 RoboForge
– robot fighting tournament game
– almost pure Java
– received an “Excellent 87%” rating from
PC Gamer Magazine
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4. Why use Java for Games?
 The
usual reasons:
– cross platform support, code reuse, ease of
development, availability of tools
 Less
well known reasons:
– efficient implementations for small devices
– developer interest
– platform maturity
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5. Java Compared to C
 Common
–
–
–
–
wrong ideas:
C is compiled, Java is interpreted
build-time compilers produce faster programs
C is faster then Java
Java programs require no porting
 A correct
idea:
– Java programs are faster to write and less buggy
than equivalent C programs
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5.1. C is compiled, Java interpreted
is false
 Both
C and modern Java Virtual Machines
(JVMs) compile code.
C
compiles at build-time.
 The
JVM compiles at run-time.
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5.2. Build-time Compilers Produce
is false
Faster Programs
 Run-time
compilers can optimize much
better then build-time compilers
– they know the actual hardware being used
– they know how the code is being used/executed
– they can perform “dangerous” optimizations
because they can recover
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5.3. C is Faster than Java
C
is false
is faster at some things
– array access
 Java
is faster at some things
– much faster memory allocation
– better recursion and inlining
 Over-all
performance is roughly equivalent
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5.4. Java Programs Require No Porting
is false
 Pure
Java programs will run on any JVM,
but may need ‘tweaking’ to improve system
specific performance.
– 85% - 90% of a game will probably require no
changes
 Still
a big winner over trying to port C/C++
programs.
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5.5. Java Programs are Faster to
is true
Write and Less Buggy
 Many
C/C++ programmers who have
moved to Java have reported 2 to 10 times
productivity increase.
 The
design of Java prevents whole classes
of “late detection” bugs
– no uninitialized variables
– no wild pointers
– no array over-runs or under-runs
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6. Evaluating Java for Game Development
 “Evaluating
Java for Game Development”
Jacob Marner
Univ. of Copenhagen, Denmark
March 2002
– a 320 page report (90 page text, the rest code)
– http://www.rolemaker.dk/articles/
evaljava/
 I have also placed it in
– Java Games/Background/
JavaForGames.pdf
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Main Conclusions
 Java
is a bit slower than C++ for executing
games (1.2 - 1.5 times slower)
– but the slowdown depends on the coding style,
the JVM version, the application
– real limits are 3D hardware, networking
 Productivity
with Java is higher than with C++
– about 1.3 times better in some studies
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 Java
is a good choice for simpler games
– e.g. 2D, smaller, less complex graphics
 Java
combined with C++ is a good choice
for more complex games
– Java can use C++ / C via its Java Native
Interface (JNI)
– C++ is suited to low-level functionality,
Java is better for the top level
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 Java
games can be speeded up by using JNI
to directly access DirectX, OpenGL,
Windows SDK, etc.
 Java
has not been ported to any of the
popular game consoles yet
– console games make up ~70% of the market
 PC
games are most of the rest
– at JavaOne 2001, Sony and Sun announced that
they would port a JVM to the PlayStation 2
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7. The Java Games Profile
 The
Java Games Profile is a gaming API
being developed at the moment
– aimed at game consoles and PCs
 target
consoles will have 32-64 MB of RAM, fast
3D graphics hardware, large hard disk space
– based on the Java Micro Edition
– partners include Sony, Sega, Sun, GameSpy
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– started June 2001; still under development
– some details at
http://jcp.org/jsr/detail/134.jsp
– also known as Java Specification Request 134
(JSR-134)
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Specification Scope
 Areas
–
–
–
–
–
–
–
–
being considered:
3D Modeling and Rendering
3D Physics Modeling
3D Character Animation
2D Rendering
Game Marshalling and Networking
Streaming Media, Sound
Game Controllers
Hardware Access
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Where the Java Games Profile Fits
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Technolgies Old and New
 Existing Technologies
used:
– Java 2D, Java 3D, JMF, AWT, I/O, networking
– JDK 1.4. features for hardware
 screen
management, timer API
 VolatileImage for storing images directly to
graphics card memory
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 New
Technologies:
– Physics Modeling
– Character Animation
 appearance,
behaviour, realistic animation
– Game Marshalling and Networking
 find/join
an online game; data communication
– Game Controllers
 e.g.
joysticks, steering wheels, light guns,
dance pads
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8. Game Engines
 A game
engine is set of libraries/packages/
classes which support various games
functionality
– the programmer does not have to build a game
from nothing
– e.g. sprite control, playing area management,
background generation, physics
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What is a Sprite?
We will create a simple Sprite
class later in the course.
 A sprite
is a (moving) graphical object
visible on the screen
– it is aware of collisions, mouse/keyboard
interactions, edges of the playing area
– it can be told what direction to move in and
how fast to travel
– it has a z-level, which dictates its drawing order
on screen
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Free Game Engines
 A lot
of free game engines have been
developed in Java. See:
– Java Games/Background/gameEngines.txt
 pointers
to game engine sites
– Java Games/Background/sourceForge.txt
 pointers
to game and game engines maintained at
the SourceForge Web site
 SourceForge
maintains lots of different
software projects, not just Java games.
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