Game programming – The “Why”, “What” and “How” with
Graphics Objects
Lakshmi Prayaga, Lecturer, Computer Science Department,
University of West Florida, Pensacola
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Abstract
Game Programming is the latest buzz word in the computer science educational
curriculum. Many universities across the world are offering complete
CS degree programs in game programming while others such as the Art
institute of Portland have summer camps for teens in game programming
(Ai of Portland, 2005). This brings us to three interesting questions,
The “ Why”, “What” and “How” of
game programming. This paper serves the purpose of analyzing these
questions within the context of a Visual basic.Net application. A discussion
on the choice of Visual Basic .Net as the environment to create and
manipulate the objects in the game is also presented. The code used
is also included in the paper.
1 WHY GAME PROGRAMMING?
The idea of using games for educational purposes in K-12 and also
for higher education is well documented (Dempsey etal, 1997, cited
by Seay and Scott). However, educators are split on the idea of using
games in a class room. Some feel it is very effective to teach a concept
while others feel it takes up valuable class time. But research
(J.C.Herz , in JoyStic Nation, p 1-2 cited by Seay and Scott, Affisco,
1994, p.171 cited by Feldgen and Clua) shows that students these days
have a totally different way of learning. They react more to interactive
learning. In fact Affisco coins the word ‘Edutainment’ a
combination of entertainment and education and points out that if students
are not entertained while they learn, the instructor has lost them.
Herz argues that, “If your memories have pop soundtracks or big-screen
kisses, if you've ever told an anecdote with instant replays or a coda
of stadium applause, it's because you've been brought up with media
that furnish those conventions. Video games provide a new set of conventions,
which are being rapidly assimilated, as you read this, by a legion
of six-year-olds. Their mental grammar is going to reflect that, just
as the baby boomers' worldview echoes the impact of television. But
whereas TV turned kids of the fifties and sixties into a nation of
screen watchers, videogames have created a cadre of screen manipulators
( p.1-2).” Continuing on this thought, Lave(1991) and Mcllelan(1995)argue
learning happens within a context and culture of a society, i.e. it
is situated. The typical student today(2000 – present) is very
well versed in playing games on the computer. They acquire high levels
of skills in playing these games and in trying to beat the computer.
In addition, many argue that (Coleman et al. 2005) “videogames
are the initial draw to technology for a number of students in the
first place”, (Pleva 2004) they provide a “stepping stone
for kids into the world of technology. Students who play computer games
tend to be more comfortable with the technology and more adept at using
it.”.
Ideas such as these expressed by educationalists show that games
are here to stay and are being used as educational tools, and are in
many
cases successful at delivering educational content in a way that students
internalize those concepts being presented. Seay and Scott cite a reference
to an article in the American Scientist which shows that the IQ of
present day students is increasing and one of the theories for the
increase in IQ “is that our increased exposure to visually rich
mass media---television, computers, video games -- has enabled us to
perform better on spatial-visual tests. The theory states that the
ability to interpret different forms of information from different
media and make some kind of sense of it is what these IQ tests actually
test for.”
The game environment is almost like a comfort zone for the student
by which he is not intimidated. It is in fact his preferred choice
of context to work in. It is therefore an area that can be used advantageously
by educators to motivate students to be focused in and complete their
assignments. In fact Feldgen and Clúa show that most students
in the year 2003, chose the context of the game environment for their
projects compared to the context of engineering, calculus or business
and were also successful in completing their projects. This shows that
the gaming environment has a heavy influence on the students mind and
therefore also acts as a good motivator. Not surprisingly, many universities
(GameDev.Net05) such as University of Pennsylvania, University of Denver,
Middlesex University UK, University of North Texas have now started
to think seriously about including game technology into the CS curriculum.
2 WHAT IS GAME PROGRAMMING?
“Game programming is a subset of game development, is the programming
of computer, console or arcade games. Though often engaged in by professional
game programmers, many novices may program games as a hobby. Most software
engineering students program games as exercises for learning a programming
language or operating system. In fact, the Unix operating system and
the C programming language exists because the original programmers
wanted to play games” (Wikepedia 2005).
Game programming is both an interdisciplinary and an intra-disciplinary
field. It is an intra-disciplinary field of computer science because
it includes (Masuch, Freudenberg 2002). “Computer graphics, AI,
simulation, user interface design are core components of every game.
And more: network techniques, multimedia, databases and many other
disciplines take part in game development”. It is an interdisciplinary
fields due to its heavy dependence on photography, physics, imagery,
audio and video technology, in short all elements of multi media technology.
The above topics provide the necessary background knowledge to deal
with the complex relationships among many abstract and concrete components
of game programming. Some of these components are the story line, picturization,
characters, shapes, sound, interactivity and other multimedia effects.
These components can broadly be classified into two categories, visual
and non-visual. This paper focuses on creating and using graphics objects
as the primary source of visual representation of the game being planned.
Graphics objects form the core of game programming because images used
in any game have properties which are similar to the properties of
a graphics object. An example is that of an image bound within a rectangular
or circular graphics object. We show how geometric shapes can be made
into objects that have properties, events, and methods suitable for
game programming.
In addition to introducing students to the idea of “objects”,
game programming can be used to introduce introductory data structures
such as arrays and records. Together, these topics form the core of
an introductory object oriented programming (OOP) course with gaming
as the context. As discussed earlier, students can relate to this context,
and hence there is a better chance of meeting and improving student
learning outcomes in an introductory OOP course. In recent years game
programming is being introduced into the CS curriculum in many different
ways such as (deLaet et al. 2005)“a games course for women, a
software development course that uses games as projects, an introductory
games programming course in Java, and an advanced graphics course that
focuses on games”.
Regardless of which way a game programming course is introduced,
there are some essential elements of the subject which must be taught.
These
include graphics objects, animation, physics of collisions, collision
detection, collision response and multimedia effects. The elements
of game programming presented in this paper implement the recommendations
of Cunningham et al. (2004) as shown in Fig1.
Figure 1
Figure one provides a framework that explains the design process and
is discussed below:
- Problem statement: In order to create a game, it is important
to formulate the story line, followed by identification of the individual
components
participating in the game and their relationships. An example is
to visualize a scenario when in which a group of objects appear on
the
screen and start moving randomly.
- Model: Once the statement of the problem is verbalized,
the next step is to conceptualize or abstractly visualize a model
that represents
this problem.
- Geometry: This conceptualization must now be translated
into figures, outlines or geometric shapes. For example the objects
can be thought
of as spherical, rectangular, triangular or polygonal objects which
have geometric properties such as points, angles, vertices and
lines. Objects may also have irregular shapes, with pictures of trees,
birds,
animals etc.
- Image: The last phase is to visually depict this model
on the screen of a computer by using an image that corresponds to
this model.
These four phases constitute the building blocks of game programming.
As shown in fig.1, looping back to the initial phase (or to any phase
from any phase, similar to the waterfall life cycle model in software
engineering - Schach02) may occur many times during the design of
the program. Only one loop back is shown in the figure to avoid clutter.
The next section is a discussion on the implementation of these core
concepts.
3 THE HOW OF GAME PROGRAMMING:
We discuss the implementation of the principles of game programming
based on fig1 with reference to a specific game environment being designed.
Graphical reusable/replaceable objects are used to illustrate the use
of the four elements of game programming discussed above.
The problem statement/ story line of the game: The game being designed
is a combat operation between different geometric shapes. The user/player
controls one of the objects and the rest of the objects try to hit
the user/player object and destroy it. The elements required at this
stage include creation of objects for the game, the movement of these
objects (animation) on the game board, the collision of objects, the
result of this collision and audio clips to add sound effects to the
environment.
The model: A model is an abstract visualization of the problem being
discussed. The model for this game is the interaction between the two
sets of objects, system/game controlled objects and the user controlled
object. These shapes do not have any social skills, so when they interact
with the user object the user object is either destroyed completely
or shattered into smaller pieces. So, the outcome of the combat is
collision, destruction or the survival of some objects
Geometry: The geometry is the crucial piece of game programming.
It is at this stage that decisions regarding the size of the game board,
the types of objects, the shape of the objects and the location of
the objects on the board, have to be made. During the game, various
geometrical transformations of the objects have to be performed, such
as rotations, translations, scaling, etc. Students designing the game
must therefore be particularly familiar with coordinate geometry, linear
algebra and trigonometry to be able to make these decisions. The importance
of geometry in game programing is also evident as it is included as
one of the major courses students wishing to major in game programming
must take. (Coleman et al. 2005). We assume that students entering
to take a course on game programming have this pre-requisite knowledge.
Image: The images on the screen follow the decisions made in the
geometry phase. Images translate the model into a visualization. Depending
on
the expertise of the programmer, imagery can become a very complex
element of game programming.
Why Visual basic.Net: The choice of Visual basic.Net as the programming
language to introduce students to game programming was the result of
an experiment conducted on a batch of at risk high school students.
These students were ninth graders who were participants of the “reach
for tomorrow” program which is designed to motivate at risk students
to acquire military scholarships and pursue higher education. (Reachfortomorrow.org)
The students had no prior computer programming experience and were
also not very comfortable using the computer. The limitations under
which the experiment was conducted were:
- Limited amount of time (two and a half hours)
- Students having limited computer experience
- Zero programming experience
Given these limitations, I needed to choose a language that was user
friendly and did not have a high learning curve. Visual basic.net seemed
to fit this bill. I used VB.net to get the students develop a simple
game that included the basics of game programming by
- using picture boxes to hold the objects used in the game
- simulating animations and movements with timer controls
- simulating ideas of velocity, speed, direction
- including the idea of collision detection and response
The result of this experiment was that the students enjoyed the experience.
In fact students at this stage were motivated enough to experiment
with changing the speed, direction, size and other aspects of the
objects used in the program. This shows that choosing the proper context
(games)
and providing the proper and easy to use programming environment
(user friendly VB.Net tool box) generates the required motivation for
students
to pursue their goals. Visual basic.Net is a very user friendly language
because of its rich GUI environment. Presented below is the design
of an application that includes the basic elements of a game program
discussed so far.
4 DESIGN
The table below shows the design of the game in terms of the elements
used in the game and their corresponding VB.Net elements.
| Game Element |
VB.Net Element |
| An area to play the game |
PictureBox |
| The Players |
Graphics Objects |
|
Movement of players |
Controlled by timer Controls |
|
Collision - detection |
Intersectswith property |
| Collision – Response |
Simulation of Explosion and collision |
The graphics objects used in this program are created by instantiating
the shape object named ObjectShape. Since the objectShape is an object,
we can reuse it and instantiate it as many times as necessary. The
ObjectShape object has properties and events as follows:
- Properties:
Color, shape, size
- Events:
Click
Using this method we set up six small ellipses which are the opponents
in the game and one slightly larger ellipse which is controlled by
the user. The user controls his piece with the mouse, so he can move
around the play ground.
5 THE WORKING OF THE GAME
To maintain clarity and for demonstration purposes the elements of
game programming incorporated in this example are kept simple. These
include animation/movement of the objects, velocity, collision, graphics
objects and audio rendition.
Animation
Animation is provided by using a timer control. The timer control’s
tick event is used to move the graphic object on the screen, horizontally,
vertically or diagonally. The timer control’s tick event also
checks for collision occurrence and if collision occurs, the function
collide is called to swap the velocities of the objects. The code for
moving the objects is included in the moveAround sub procedure.
Collision
Collision detection and response are other key elements of game programming.
There are several kinds of collision responses that occur when objects
collide. We discuss three types of collision responses - one in which
an object bounces off a wall, one in which two objects have a head
on collision and bounce off each other and a third in which an explosion
or shattering occurs on collision
- A ball hits a wall and bounces off. (code in the sub procedure
moveAround)
- A ball collides with another ball and the two balls bounce
off of each other. (code in the sub procedure collide) In the sub
procedure collide
the velocities of the two objects are interchanged.
- The collision response resulting in an explosion is achieved
by disposing off the object (user controlled object) and creating
six smaller objects
on the screen. This creates the effect of an object being shattered
and explode into small pieces.
Sound:
The next element used in the game to provide sound effects is audio.
SoundWav.vb is a simple class file used in the application to provide
the functionality of playing a wave sound file when necessary. This
is a modified version of a class file available on the internet (soundFile)
We have used two different sound files for collision between the game
objects and collision between the game object and the user object.
When collision occurs between the game object and the user object we
have a “crashing” or “exploding” sound, and
when collision occurs between game objects we have a ‘ding’ sound.
This completes the design of the game elements.
User Interface:
The program has two buttons, Wall Collision/Dispersion and Ball Collision
(Figure2). The Wall Collision/Dispersion checks for
- Collision of the small balls with the wall and if collision
occurs the balls bounce off the wall.
- It also checks for collision between the small ball and
the large ball and if collision occurs the large ball shatters into
small pieces.
(Figure3)
The Ball Collision button checks for
- Collision between two small balls on the screen and if
collision occurs, the swapping of velocities takes place. (Figure4)
- It also checks for:
- collision between the small ball and the larger ball which
is the user controlled piece and if collision occurs the user control
is disposed.
- Wall collision is also included in this button. See figures
1, 2 and 3 for the game in action
Figure1
Figure 2
Figure 3
6 CODE FOR THE PROGRAM
Part A – The Class file - Object Shape:
Part B Class for Sound File –
Part C – Main program:
7 CONCLUSION/FUTURE WORK
Game programming can be a useful and powerful tool. It can be used
in educational settings to help students understand abstract concepts
through games, with which most students are familiar. Examples
of introducing abstract concepts through game programming include OOP,
data structures, principles of physics, chemistry and mathematics.
We also believe that game programming can exert a positive influence
on at risk students by providing them with much needed excitement
and motivation to pursue higher education as was evident by our
experience
Additionally, game programming is also a good field with plenty
of opportunities as a career choice. Several web sites such as International
Game developers association(igda.org) provide detailed information
on the type of jobs available in the gaming industry along with
the
salary ranges. In attempting to promote this idea of introducing
game programming to students, our future work will concentrate
on developing a set of tools for the most commonly used game programming
techniques with a grounding in physics as applicable to the gaming
environment.
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About the author
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Lakshmi Prayaga is a lecturer in the
Computer Science Department, at the University of West Florida.
She is the co-author of a text book, “Programming the Web
with ColdFusion MX and XHTML”. She has presented several
papers in conferences and workshops such as ACMSE, ELearn, EdMedia
and NCEI. Her research interests include building visual tools
to serve as teaching aids, web server technologies and computers
in education. |
Cite this article as follows: Lakshmi Prayaga: “Game programming – The “Why”, ”What” and “how” with
Graphics Objects”, in Journal of Object Technology, vol. 4, no.
9, November-December 2005, pp. 39-58 http://www.jot.fm/issues/issue_2005_11/column5
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