Java Game Programming
On Chapter 1, you learned what the Web has
to offer in terms of games. Most of the games you learned about
were not developed in Java because Java is a new technology and
programmers haven't had time to gain enough proficiency to turn
out interesting games. For the aspiring Java game developer like
yourself, this is very good news; the game market is wide open!
This level playing field in Java game development should give
you the energy to get busy thinking about your own game designs
as you go through toChapter's lesson and the rest of the guide.
ToChapter's lesson follows up on Chapter 1's general
discussion of Web games to focus on programming Web games in Java.
ToChapter you learn about the specific features of Java that make
it a very good language for game development. This lesson lays
the groundwork for much of the material that you cover throughout
the rest of the guide. You finish up toChapter's lesson with a brief
look at conceptual game design.
The following topics are covered in toChapter's lesson:
- Java and Web games
- Java features for games
- Game design
With all the hype surrounding Java and what it will do for the
Internet, it should come as no surprise that games are being hyped
as one of the most interesting applications of Java. Indeed, that's
probably why you bought this guide to begin with! Even though Java
includes many useful features for games, it still isn't quite
the ideal gaming language for the Internet.
Just because Java isn't an ideal Internet gaming language doesn't mean that it doesn't deliver on many accounts. In reality there probably will never be an ideal gaming language because games have such unique programming challenges and languages tend to be
designed for general use.
Although it's not the ideal language, Java does have much to offer
for mixing games with the Web equation. Java as a technology is
poised to bring interactivity to the Web in a general sense. Java
games are only one aspect of this "interactive revolution."
Java provides a level of platform independence, security, and
network support that is still unattainable in any other language.
All these issues are of utmost importance in any technology that
is to bring interactive games to the Web.
Platform independence refers to the capability of a single
executable program to run on a variety of different computer systems.
This discussion might make a little more sense in the context
of an example, so let's look at one. Consider an educational Web
page attempting to discuss desert animals and how they interact
with one another. Before Java, without using complex platform-dependent
programming languages, the Web presentation would have been limited
to text and inlined graphics. Now imagine a Java game inserted
right into the Web pages, which allows students to play the role
of a desert animal contending with other desert predators. This
level of interactivity combined with the accessibility of the
Web can't be matched by any other media. Web games written in
Java will truly change the way you perceive the Web as a whole.
By the way, this example isn't just something I made up for the
purposes of this discussion; you will actually develop a game
on Chapter 10 that is very similar to this
You've seen some of the aspects of Java that are beneficial in
making Web games a reality. It's now time to look at the specifics
of the functionality that Java provides for developing games for
the Web. The primary areas of importance for game programming
are the following:
- Graphics and animation
- User input
- Media management
As you learn about each of these different areas of game programming,
I want to help put them into perspective by explaining how they
would impact the development of a Java Space Invaders game. This
will help you to see how each of these areas impacts a real game,
and it might also help you get ideas about designing a real game.
What good is a game without graphics? In most cases, not much!
Fortunately, Java delivers the goods when it comes to graphics.
The standard Java API includes wide support for all kinds of neat
graphics features such as images, color models, and 2D graphics
primitives. Although Java as a whole is still largely limited
by its relatively slow performance, the support is in place for
very powerful graphics. As future releases of Java address the
speed concerns, game programmers will be able to more fully exploit
the graphics capabilities Java provides. You get the whole scoop
on graphics later this week on Chapter 5, "Java
What about animation? Most games would be pretty boring without
it! Although the standard Java API doesn't provide any specific
animation support, it is riddled with features that make implementing
animation very easy. One of the most important aspects of Java
is its multithreaded design, which provides a powerful framework
for establishing the all-important timing necessary for animations.
You learn all about implementing animation in Java later this
week on Chapter 6, "Sprite Animation."
In the context of a real game, the graphics and animation form
the majority of the look of the game. In a Space Invaders game,
for example, the graphics and animation account for the aliens,
the player's ship, any barriers that the player can hide behind,
the missiles being fired back and forth, and any explosions that
take place when a missile collides with something. Furthermore,
the display of the title screen and score would also fall under
the area of graphics programming.
User input is a very critical area of game development because
it dictates how a game "feels" to the game player. User
input is also important because it establishes the primary interface
between the player and the game. Java provides support for the
two major input devices in use on most computer systems these
Chapters-the keyboard and mouse. When programming in Java, you monitor
these input devices by responding to user input events generated
when the user manipulates one of the devices.
Although it would certainly be nice if Java supported other input
devices such as joysticks and flight yokes, the reality is that
these devices aren't available on a wide variety of platforms.
Hopefully a future version of Java will provide some degree of
support for these gaming devices, because they are typically used
in addition to the keyboard and mouse.
Even without the support for game-specific input devices, the
support for the keyboard and mouse is enough to provide an effective
user interface to most games. If you're skeptical, you can judge
for yourself next week on Chapter 9, "Handling
User Input with Java."
Using the Space Invaders example again, the user input requirements
of the game consist of the inputs necessary to control the player's
ship and fire missiles. For a game like this in which the ship
simply moves from side to side, the best approach is probably
to just use the left and right arrow keys to handle the ship's
movement. You could also detect side to side mouse movement and
use it to control the ship. You would designate another key, such
as the spacebar, as the fire button. Likewise, a mouse click could
also serve as the fire button for the mouse interface.
Rounding out the "big three" areas of game development
is sound. Sound is currently the weakest area of Java's support
for gaming. Release 1.0 of Java supports playing sound waves only
in the ULAW format, which is popular on Sun workstations. Although
the current Java sound support provides built-in sound mixing
and the capability to play looped sounds, it is pretty limited
because all sounds must be in the ULAW format (which is a low-quality
sound format). Furthermore, there is no support for manipulating
sounds at a lower level, which is often useful in games. A future
release of Java will no doubt remedy many of the current limitations
in regard to sound.
Sun is already busy at work on a future add-on to Java that will provide lots of neat sound features such as MIDI (Musical Instrument Digital Interface) music and support for other sound formats.
Even with its limitations, the current Java sound support is enough
to add simple sound effects and music to Java games. Actually,
the fact that Java provides a built-in sound mixer in the first
release is a big deal. Contrast this situation with that of Windows
3.1, which didn't have any sound mixing support until very late
in the product cycle.
It might seem strange that I'm comparing Java to an operating system (or shell, at least) in Windows 3.1. This brings up an interesting point regarding what Java really is. Java is not just a language; it is also a runtime system that acts very much like
an operating system at times.
You learn all about sound programming in Java, as well as the
ULAW sound format, next week on Chapter 12,
"Playing Sound with Java."
Going back to the Space Invaders example, the sound programming
aspect of the game consists of writing code to handle all the
sound effects in the game, as well as the background music. You
might wonder how to add music considering the fact that Java doesn't
yet support the popular MIDI music standard. The truth is that
the original Space Invaders arcade game was developed well before
the MIDI standard, so someone improvised back then! Similarly,
you have to improvise music in Java by playing looped wave sounds
repeatedly. Admittedly, this isn't the ideal approach, but it's
the only approach you have-for now.
Now that the concept of a "computer in every home" is
inching closer to reality, game developers can no longer ignore
the potential of multiplayer network games. The desire of game
players to connect and play games with other real people is just
too strong to ignore. This is evident in the recent surge of commercial
games that support network play. CivNet comes to mind as an example
of a popular single player game (Civilization) that has been revamped
for network play.
Networking is the one area where Java really shines because it
is such an integral part of the Java runtime system. Unlike other
popular game programming languages such as C and C++, Java was
designed from the ground up to support networking over the Internet.
For this reason, the networking support in Java is much easier
to use and a lot more secure than add-on networking libraries
Network programming has long been a very complex and highly specialized area of software development. Prior to Java, most programmers had to focus all their efforts on network programming alone just to develop enough skills to do anything useful. Java has
changed all that and made network programming a realistic pursuit for the rest of us.
Combine Java's extensive network support with its platform independence
and you have a gaming platform that crosses all boundaries for
availability to users. With a networked Java game, you could be
sitting in front of a Windows 95 machine playing a game of Poker
with players in other parts of the world using completely different
machines, such as Sun workstations or Macintoshes. That's about
as good as it gets when it comes to distributed game play! You
learn all about network programming in Java on Chapter 18,
"Networking with Java."
Using the Space Invaders example again, there isn't a very clear
way to add network support because the original game was basically
a single player game. However, nothing is stopping you from adding
a mode in which two players join forces and battle the aliens.
Using this approach, you have to define a means of sending data
back and forth between the players so that each player's game
is up to date with the other player's actions. This technique
is known as synchronization and is a key topic on Chapter 17,
"The Basics of Multiplayer Gaming."
The last issue in regard to Java's support for games is media
management. Media management refers to the tracking of
media objects (graphics, sounds, and so on) as they are being
transferred across the Internet. If you didn't guess, the whole
issue of media management is unique to Web games because traditional
games reside on a single machine and get all their data from a
CD-ROM or hard drive.
To understand why media management is an issue, think about where
the data comes from when a game is playing. In a traditional game,
the data comes straight from the hard drive or CD-ROM. When you
consider distributed Java games, it becomes difficult to nail
down exactly where the game's content is coming from. Of course,
a Java game executes locally on the end user's machine, but it
is initially transferred from whatever Web server it is installed
on. Java games could certainly still be shipped on a CD-ROM like
traditional games, but doing so would bypass the whole point of
incorporating Java games into online Web content. For this reason,
most Java games transfer their data (media objects) over an Internet
Because transferring data over the Internet takes a finite amount
of time (often too finite!), it becomes necessary for Java games
to keep up with the time at which certain data is available for
use. In other words, you don't have the luxury of speedy hard
drive access, so you have to take into account the amount of time
it takes to transfer data over an Internet connection. For example,
it would be a bad thing to display a game screen when you have
the graphics for only half of the objects being displayed. Java
provides a feature for keeping up with which media objects have
been transferred, and therefore which ones are available for use.
Unfortunately, the current release of Java only supports the tracking
of images, and not sounds. You learn the details about tracking
images later this week on Chapter 5, "Java
Graphics Techniques." Media tracking support for sounds and
other types of media has been promised in a future release of
Returning to the trusted Space Invaders example, it's not too
difficult to determine what media objects the game is composed
of. Basically, each graphic element in the game is stored as an
image, which has to be transferred for the game to run correctly.
In addition to the images, you also have to deal with the individual
sound effects and the looped music sound. These elements are equally
important media content that have to be transferred along with
Now that you understand some of the reasons that Java is cool
for writing games, let's take a conceptual look at game design.
The rest of toChapter's lesson focuses on the flow of thought necessary
to come up with a game plan. This thought should take place before
you begin to write any Java code. I know you're probably itching
to get into the technical side of things, but please be patient.
You'll get a good dose of Java code in due time!
Do you have some ideas of games you would like to write? If so,
you probably already realize that coming up with a good game idea
is often the easy part. Taking a game concept and making it reality
is where most of us fall short. That's okay; you just have to
take it a step at a time and think through the development process.
The first step in taking a game from concept to reality is to
get a solid idea of what you want the game to be. This doesn't
need to be an itemized list of every scene and every little creature
and interaction. It simply needs to state some minimal ground
rules about what your goal is for the final game.
Here are the key items you should address when beginning the game
- Basic idea
- Play modes
The first thing you should do is determine the basic idea behind
your game. Is it a shoot-em-up, a maze game, a role-playing adventure
game, or some mixed combination? Or do you have an idea of a game
that doesn't really fit in an existing category? Is the object
to rescue good guys, kill bad guys, or just explore a strange
environment? What time frame is your game set in, or does it even
have a time frame? Write all this stuff down. Whatever comes to
mind, write it down, because brainstorms come and go and you don't
want to forget anything. Forcing yourself to formalize your ideas
causes you to think more about the game and clears up a lot of
If you are having trouble coming up with a basic game idea, think
about the influences of a lot of the popular computer games. Many
games are based on movies, some on historical events, and others
on sports. Ultimately, computer games are models of the world
around us, whether fantasy or real, so look no farther when dreaming
up your game. Movies in particular can provide a lot of good creative
settings and storylines for games.
Currently, there are even a few cases in which a game idea has served as the basis for a movie, which is pretty surprising. The really strange thing is that some of the movies are based on games with a very limited plot. For example, the immensely popular
Mortal Kombat game, which is basically a straight-up fighting game with no plot, was made into a movie.
Regardless of your inspiration, just remember that your game has
to be fun. Actually, that's why I think computer games are so
alluring to programmers. The overriding design goal is always
to maximize fun! Who wouldn't want to spend all Chapter trying to
figure out the best way to have fun? If your game isn't fun to
play, the most dazzling graphics and sound won't be able to save
it. The point I'm trying to make is that you must make fun the
priority when designing your game. After you have a basic idea
of what your game will be and you've decided that you're going
to make it fun at all costs, you can develop a storyline.
Even if your game is a simple action game, developing a storyline
helps you to establish the landscape and think up creatures to
populate your game world. Putting your game in
the context of a story also brings the game player closer to your
world. For games in which the story is a more integral part, it
is often useful to develop a storyboard along with the storyline.
A storyboard tells the story scene by scene by using rough
sketches of each scene. A storyboard basically enables you to
create a visual layout of the entire game, based on the story.
Having a storyboard to reference helps ensure that you don't lose
sight of the story when you get into heavy development.
The final thing to consider when laying out your initial game
design is what play modes you will support. Will it be single
player, two player, networked, or some combination? This might
sound like a fairly simple decision, but it can have huge repercussions
on the game logic later. Even though Java provides a lot of support
for networking, network games typically incur a significantly
more complex design.
On the other hand, many single-player games will require some
degree of artificial intelligence to make the computer opponent
challenging to play against. Artificial intelligence can easily
get complicated and difficult to implement, so you need to weigh
your resources heavily into your game design when deciding on
play modes. Speaking of artificial intelligence, you learn all
about it on Chapter 15, "Teaching Games
ToChapter you learned what Java has to offer games on the Web. Some
of the requirements of Web games were discussed, along with how
Java addresses many of the problems inherent in moving games to
the Web. You learned about the primary features of Java that directly
impact game development, along with their benefits and limitations.
In short, you learned toChapter that Java, although not perfect (yet),
is positioned to be an extremely viable development tool for games
on the Web.
You finished up toChapter's lesson with a discussion of general game
design ideas. Although not etched in stone, these ideas and suggestions
serve as good guidelines when you start working out your masterpiece.
This discussion also serves as a good ending to toChapter's lesson,
because you will continue with more theory on Chapter 3.
Tomorrow's lesson focuses on object-oriented programming in Java,
a topic you won't want to miss!
|Q||Does Java provide support for 3D graphics?
|A||No, not yet. The standard Java 1.0 API has no support for 3D graphics, but a future release of Java could well fix this. Also, there are some third-party Java graphics libraries in the works that might make
viable alternatives to writing your own 3D graphics code.
|Q||How do you play music in Java?
|A||Currently, the only way to play music is to loop a sampled sound clip stored in the ULAW sound format. There is talk of MIDI extensions for Java, but nothing real has surfaced yet. Keep your eyes open, though!
|Q||Are there any limitations to how Java games can be networked?
|A||Not really. As long as you stay within the network security bounds imposed by Java, which you are forced to do anyway, the options available for network games are wide open. You can theoretically have as many
players as you want, interacting however you choose to allow them.
The Workshop section provides questions and exercises to help
solidify the material you learned toChapter. Try to answer the questions
and at least go over the exercises before moving on to tomorrow's
lesson. You'll find the answers to the questions in appendix A,
- What user input devices does Java currently support?
- What are some limitations of the sound support in Java 1.0?
- What is a media object?
- What is a storyboard used for?
- Get on the Web and check out some Java games. Hint: A good
place to start is the Gamelan Web site, which is located at http://www.gamelan.com<.
Gamelan has an entire section devoted to Java games.
- Perform the preliminary design for a game of your own, addressing
each of the issues mentioned at the end of toChapter's lesson.
- Check out Javasoft's Web site at http://www.javasoft.com<
for the latest news on Java; who knows, by the time you read this
there could be new enhancements to Java such as more advanced
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