Programming assignment #3 - 3D Video Game
CS 248 - Introduction to Computer Graphics
Autumn Quarter, 2008
Game proposals due Monday, November 3 by 5:00pm
First demos on Friday, November 14
Final demos on Wednesday, December 3
Writeups due on Friday, December 5 by 5:00pm
Your assignment is to write a 3D video game using OpenGL. You are free to
design and implement any sort of game you like, as long as it incorporates the
required functionality described below. For purposes of this project, we
consider a 3D video game to be an interactive 3D computer graphics application
that has a challenging goal, is fun to play, and incorporates some concept of
scoring or winning and losing. It is not required that your game idea be
original, but originality will be rewarded with extra credit. It is also not
required that the game be intrinsically three-dimensional; you can take a 2D
game and render its components three-dimensionally, converting game pieces to
solid models, lighting them, etc. (Of course, games that are intrinsically
three-dimensional probably have a greater chance of winning a spot in the
competition.) If you have any questions about whether your idea meets the
criteria for a 3D video game, please ask the course professor or a TA. Your
game proposal (due November 3), and our feedback to you afterwards, should help
you in developing your game concept.
You are permitted (and encouraged) to form teams of 2-3 people and partition
the work among the team members. The work expected from each team will be
proportional to the size of the team. You can use the class newsgroup
su.class.cs248 to find prospective team members.
Each team should submit a single game proposal, jointly authored by all team
members. You may change the composition of your team at any time prior to
November 26 (one week before final demos). However, changes after the first
demos (on November 14) are strongly discouraged.
You are not required to work on any particular platform. You are welcome to
use the myth machines in Gates B08, but you are also welcome to use a laptop
(any operating system), or even the Cray supercomputer in your dorm room. If
you choose to use a mobile platform, such as a Nokia N95 cell phone (which we
can loan you), then we will not expect the same performance or model complexity
in your game that one can acheive on a faster platform or a larger screen.
However, the fundamental requirements for the project are the same.
Within the overall framework of your video game, you are required to include
the following functionality:
- 3D viewing and objects.
Your game environment must be a scene consisting primarily of 3D elements, as
opposed to only "flat," 2D sprite-based graphics. Your game should provide
perspective views of your 3D scene where at least sometimes the viewpoint
changes smoothly under some combination of user and program control. To
produce these views, you should implement transformation, clipping, and
hidden-surface removal of your 3D scene using OpenGL.
- User input. Your game must allow players to interact with
the game via keyboard or mouse controls. Alternatively, you can use joysticks
or more elaborate user interface devices (provided that you supply the required
devices for your program demonstration sessions; see below).
- Lighting and smooth shading.
Your game must contain at least some objects that are "lit" using OpenGL's
lighting model. For these objects, you'll need to define normal vectors and
materials, as well as create one or more light sources. See Chapter 5 of the
OpenGL Programming Guide for details on implementing lighting and
- Texture mapping.
You must implement texture mapping for at least one of the 3D objects in your
video game. Chapter 9 of the OpenGL Programming Guide describes how
to implement a variety of texturing techniques. If you want, you can use your
paint program from assignment #1 to create 2D texture maps in the .ppm
image format, and/or borrow the xsupport source code from assignment
#1 to load .ppm files into your game for use as textures.
In addition to these basic requirements, your game should incorporate some of
the more advanced computer graphics techniques listed below, depending on the
size of your project team. In particular, you are required to implement at
least 2*N of these additional techniques, where N is the
number of people on your team (i.e. groups of three people need to implement
six techniques, individuals working alone are required to implement only two,
etc.). Of course, you are encouraged to implement as many of these techniques
as you can, depending on the requirements of your particular game engine, as
well as using any other ideas you read about or invent on your own. Extra
effort will be rewarded with extra credit.
- On-screen control panel. Many 3D video games reserve
part of the display area for an on-screen control panel, which may include text
or 2D graphical elements for user controls, scoreboards, etc. Flight simulator
games often superimpose 2D graphical overlays on the 3D world, thereby creating
a "Heads Up Display (HUD)." You can implement a control panel for your game
using a variety of techniques in OpenGL, such as orthographic projection and
the stencil buffer. Text primitives are not explicitly supported with OpenGL,
but GLUT and the window system extensions (GLX, WGL, etc.) both provide
commands to help render text.
- View frustum culling. In video games with complex
3D environments, it is necessary to limit the number of 3D primitives drawn
each frame in order to maintain interactive rendering rates. One way to do
this is to avoid drawing any 3D objects which are outside of the viewing
frustum of the camera. A more sophisticated technique is to pre-compute
bounding volumes for objects and then test each bounding volume to verify that
some part of it intersects the view frustum before drawing its contained
objects each frame. Finally, for even greater efficiency, you can organize
your objects (and bounding volumes) into a tree-like data structure, sometimes
called a hierarchical scene graph. Object hierarchies are discussed
in Chapter 7 of the textbook. and view frustum culling is discussed in Chapter
16 of Möller and Haines's book, Real-Time Rendering.
- Level of detail control. Another way to limit the number
of 3D primitives drawn each frame is to implement level of detail (LOD) control
in your game. One simple method of LOD control involves creating multiple
versions of some of your 3D objects, varying in geometric complexity (such as
10, 100, and 1000 polygons). Then, before drawing the objects each frame, you
can pick the most appropriate version of the object to render, depending on
such metrics as the distance of the object from the viewer, the complexity of
the current scene, or a user-selectable detail level. Levels of detail
are discussed in section 9.8 of Real-Time Rendering.
- Occlusion culling. Yet another way to maintain good game
performance with complex environments is by performing occlusion culling.
Similar to view frustum culling, this technique involves using a conservative
computation to avoid drawing any parts of the 3D scene which won't be seen by
the viewer because they are hidden behind other objects. For static
environments such as buildings, you might pre-compute which regions of space
(such as rooms) are impossible to see from other regions (due to occluding
walls, for example). More information on occlusion culling is in sections
9.5 and 9.7 of Real-Time Rendering. (Don't confuse occlusion
culling with simple hidden-surface removal, which is required for your video
- Procedural and physically-based modeling. In addition to using
scanned or hand-modeled objects to populate the 3D worlds, some video games use
procedurally computed models. Chapter 20 of the textbook describes examples of
procedural modeling, including fractally-generated mountainous terrains and
L-grammars for generating models of plants. Procedurally generated textures
may be used to simulate effects such as fire, smoke, and clouds.
- Collision detection. Video games often contain moving objects
which trigger events when they collide, such as projectiles shot at a target.
Collision detection can also be used to prevent the user from passing through
walls or other objects. You can implement collision detection in a variety of
ways; the simplest might involve comparing bounding volumes of objects to
decide if they intersect or not. If you have complicated objects, a
hierarchical scene graph (see view frustum culling above) may prove helpful to
accelerate your collision detection tests. Chapter 14 of Real-Time
Rendering describes a number of collision detection techniques.
- Simulated dynamics. Your video game implementation might include
modeling dynamic behaviors and physics for objects in the 3D world. For
example, the wheels of a vehicle might react realistically as they move over
rough terrain, or a ball might bounce differently depending on its velocity,
elasticity, and the characteristics of the surfaces it hits. Realistically
animated characters in 3D graphics applications are sometimes controlled
via simulated dynamics.
- Advanced rendering effects. OpenGL makes it possible to
easily implement a wide variety of realistic rendering effects. Some of these
effects can be achieved by drawing the scene multiple times for each frame and
varying one or more parameters each pass through the scene; these techniques
are called "multi-pass rendering." Other techniques combine traditional 3D
graphics rendering with 2D image-based graphics. Advanced rendering effects
you can add to your video game include soft shadows, reflections, motion blur,
depth of field, bump mapping, environment mapping, billboarding, and projective
texturing. See chapter 6 and 8 of Real-Time Rendering as well as the
pointers on the assignment web page for examples and information on
implementing advanced multi-pass and image-based rendering techniques.
- AI. Some video games include computer-controlled agents that
require a significant degree of artificial intelligence. Many of the
techniques taught in a basic AI course are applicable to video game
development, and some links to more detailed information on game AI are
included on the course web page for the assignment. If you have any doubts
about whether a technique you are using qualifies as "AI" for this assignment,
- Game level editor. Some video games are accompanied with
supplementary computer graphics applications which allow users to design their
own game levels (scenes). If you develop your own custom application to
construct levels while writing your game, you might consider packaging it as a
separate utility program for end-users to enjoy as well!
A few hints
- This project is purposefully designed to be more open-ended than
the first two assignments of the course. You will be expected to do a
considerable amount of learning on your own, particularly in gaining experience
with programming in OpenGL. We will cover the high-level concepts of OpenGL in
class, and we have assigned some sections of the OpenGL Programming
Guide as reading. There will also be an OpenGL help session on Friday,
October 31, at 2:15 in B01. Beyond this, please take advantage of the
opportunity to consult the course professor and TAs with questions concerning
development of your particular video game. If there are computer graphics
techniques not covered in the course that you would like to implement, we will
usually be able to point you to an appropriate source of information. In order
to assist and inspire you, a web page is available at the URL:
This page includes pointers to OpenGL tutorials, information on game
development, useful utility programs, and sources for 3D models and other game
content. Additional examples of OpenGL code from the programming guide and
OpenGL and GLUT distributions are available in the class directory in
/usr/class/cs248/assignments/assignment3. Of course, you are responsible for
understanding and implementing your own video game code; sharing code or
libraries between teams is not permitted. Using source code, libraries, or
executables you find on the Internet (or elsewhere) is permitted, but is
limited to programming tools and low-level utilities. In particular, borrowing
the code that implements basic or advanced game features (as enumerated above)
is not allowed. Looking on the Internet for ideas, even looking at
sample code you find there, is permitted and encouraged. However, when you do
this, we expect you to cite your sources in your writeup.
- Interactive 3D graphics programs such as video games
place special demands on computer hardware. If your 3D world is particularly
large or complex, you will probably need special graphics hardware in order to
get real-time performance. The myth systems in Gates B08 Hall are equipped
with recent NVIDIA graphics cards, which deliver excellent 3D graphics
performance. If you develop your game on an above average platform, it will
probably be useful to add options to optionally disable expensive features.
The performance of your video game is important, so do not implement too many
expensive rendering features if the gameplay is negatively impacted! There are
some pointers on the assignment web page to sources of information on
maximizing OpenGL performance.
- Most successful video games include richly detailed 3D models, textures,
sounds, and other content for representing the game world and characters.
You have several options available in creating the content for your video game:
- Simple models can be sketched on graph paper, and the coordinates
manually typed into your source code.
- Models can be procedurally generated, as mentioned above.
- You can use a 3D modeling package and export the model in
a format your program can read.
The assignment web page contains pointers to several freely
available modeling packages.
- The GLUT library provides functions for drawing simple
3D shapes (sphere, cube, etc.)
- You can find a wide variety of 3D models, textures, and sounds
on the web; see the pointers on the assignment web page. These may
need to be converted to a format your program can use; we will provide some
example source code for loading models.
Using source code, libraries, executables, or data you find on the
Internet (or elsewhere) is permitted, but is limited to geometric
models of characters or props (but not entire environments), textures,
sounds, and low-level programming tools (like matrix packages). In
particular, borrowing code that implements required (or extra credit)
game features is not allowed. Note that sound and networking are not
on the list of features you can get credit for, so you are welcome to
download packages that help you implement them. All this said,
looking on the Internet for ideas, even looking at sample
code you find there, is permitted and encouraged. However, when you
do this, we expect you to cite your sources in your writeup. We also
expect that your video game was developed only for this course, and
that it was begun no earlier than the start of this academic quarter.
- OpenGL is window system independent, so an additional toolkit is
necessary to provide the necessary windowing and input event
management; for this we recommend using SDL or GLUT. GLUT is used for
all the examples in recent editions of the OpenGL Programming
Guide, and is available for most all common computing platforms.
A simple example program and Makefile using OpenGL and GLUT on the
myths is available in
offers a very limited set of user interface widgets (little more than
menus). If you require slightly more extensive user interface
functionality, consider trying the MUI, PUI, or GLUI toolkits; they
are easy to use, and are written entirely on top of GLUT and OpenGL.
You may recall GLUI was used for assignment 2. Documentation is
available on the web (see the assignment web page for pointers). SDL
is a little more heavyweight, and removes some of the limitations of
GLUT. In addition, SDL will help you with networking code, sound code,
and it's cross platform. Check out SDL at
http://www.libsdl.org/ for more detail. There's an OpenGL/SDL example
- You are also free to develop your video game on any computer platform that
supports OpenGL, provided that you will be able to demonstrate your program at
the two required demonstration periods in Gates B08. If your program cannot
run on the myths, you will be responsible for bringing a system to those labs
on which to run your video game. Versions of OpenGL for most common computing
platforms are available for download at sites pointed at from the assignment
- In the course of designing and implementing your video game,
keep in mind that CS248 is a computer graphics course. Focus your efforts on
the computer graphics techniques underlying the game; don't spend the majority
of your time on game design or object modeling if the graphics engine will
suffer as a result! Finally, don't make your 3D world or game engine so
complicated that interactivity suffers. Your game must be playable!
We'll be grading your advanced techniques on a bucket system: minus,
check-minus, check, check-plus, plus. Your grade on this scale will depend on
the difficulty of what was implemented. Stated simply, grades will be
proportional to effort. To get an A on this assignment, we need to see
outstanding effort on at least one advanced feature. In general, although
implementing more features will increase your grade, we prefer that you
implement fewer features but do them well, and we will grade accordingly.
In a few days, we'll send out a mailing to the class giving examples of
the amount of effort we consider "outstanding" for each of the advanced
Finally, as stated during the first class in September, you do not need to
implement a shrink-wrappable game in order to get a good grade in this
assignment. If your quarter is too busy to spend the next four weeks in Gates
B08, then don't. Implement the required functionality and two advanced
techniques, one well, and you'll get an A. Every year, many students do this
successfully. Be inspired by your colleagues who are gunning for the grand
prize, but do not be intimidated. In most years, the winning team starts only
after the assignment is released.
Video game submission requirements
The game proposal.
Your first milestone is a proposal, due by 5:00pm on Monday, November 3.
Your proposal can be brief - 1 page is plenty. Be sure to list all team
members. The proposal should clearly state the premise of your game, describe
the 3D world you plan to build for it, outline the gameplay, and enumerate the
2*N advanced techniques you plan to implement.
If you envision facing any special technical challenges (like predicting
collisions between a basketball and a hoop), list them. If you'd like
"advanced feature" credit for something you'll be spending a lot of time on,
but which is not listed above (like the ability to play against 5,000 networked
opponents simultaneously), list those too. If you envision needing any special
tools to achieve your goals, like a laser scanner or a motion capture system,
tell us how you'll get access to these tools.
Finally, you must include at least one image in your proposal - a sample
screenshot of the game in action. We don't care how you produce this image: a
scanned pencil sketch will do, or something you whip up in Photoshop,
Illustrator, KidPix, or your favorite computer art program. Carefully label
the principal components in your image. Sample labels might be: "waterfall
[here] will use real dynamics", or "[these] missiles will emit particle system
smoke". The purpose of this requirement is to help us understand your
proposal, and to help you think about how hard or easy it might be to implement
what you propose.
Only one member of a group is required to submit for the team. The submitter should:
You should need to submit just once. If your team wishes to submit a modified proposal,
it should be resubmitted as described above by the same team member who submitted
originally. A similar procedure is to be followed for submitting the video game.
- Know the SUNet IDs of all team members
- Login to any of the myths (NOT elaines)
- Create a directory which contains the text of your proposal (plain text
preferred, but we'll accept PDF) and the image.
- Run the submit script
/usr/class/cs248/bin/submit, which will ask
for the path to the above directory and SUNet IDs of the other team members.
- Take a deep breath, and start working on the video game.
Submitting a proposal is required,
and late submissions will be penalized, but your proposal will not be graded.
Neither will you be held to either the list of advanced graphics techniques you
enumerate or to the composition of your team. The purpose of this proposal is
to motivate you to begin working on the project, and to give us a chance to
guide you. We will read and respond (by email) to every proposal. Hopefully,
most of these responses will be of the form, "Cool game idea! Full speed
ahead!". However, if we see you headed towards the shoals, we'll let you know.
On Friday, November 14 you will demonstrate your partially complete video
game to a member of the CS248 course staff. To show reasonable progress, your
3D world should be largely in place, although perhaps lacking in detail or
performance, your "gameplay" should be basically working, and at least some of
the required graphics functionality (3D viewing, user input, lighting, and
texture mapping) should be implemented. The 2*N advanced techniques
need not be in place, except that depending on your game, you might need to
have already implemented some of them in order to demonstrate your gameplay.
At the demo, we will give you feedback on your game, and we will discuss with
you your plans for finishing it.
Signups for these demos will be handled electronically, as usual. You can demo
on any platform you like, even a laptop or cell phone as noted earlier.
However, all demos must be given in Gates B08. There is no need to freeze your
code before the demos. All team members must be present at the demo. Late
demos will be permitted, but will be penalized in the usual way. No writeup or
submission of source code or other files is required following these demos. In
addition to giving you verbal feedback at the demo, we will also grade you.
Since you are not submitting code, these grades will based only on what we see
during the demo. However, these grades will be simple: minus, check-minus,
check, check-plus, plus, depending on the quality of your progress.
Final demos and writeups.
Your complete video game will be demonstrated on Wednesday, December 3.
Signups will be handled electronically, as usual. No code freezing is
required. All team members must be present at the demo. During the demo, make
sure you tell us what features you have implemented. Functionality you don't
show us or that doesn't work will not be given credit.
Final writeups and code and content submission is due on Friday, December 5 at
5:00pm. To submit your video game files, simply run the script
/usr/class/cs248/bin/submit, as you did for the video game proposal. The team
member submitting will be prompted for the directory containing all the video
game files and SUNet IDs of the other members. Only one submission per team is
necessary. Your submission should include your entire game - source,
executable, makefiles, models, textures, etc. It should also include a README
file which lists your team members, describes how to build and run your video
game, and explains the
2*N (or more!) advanced computer graphics techniques you implemented.
Also, your README file should include references to any external sources you
referred to for inspiration, and it should indicate how your 3D models and
other game content were obtained. Remember - no late demonstrations or writeup
submissions will be accepted.
Separately from your joint team submission, and privately, each team member
should prepare an individual writeup by 5:00pm on December 5 specifying who
worked on which features of your game, and what percentage of the total work
each team member did. Your writeup should be a single text file. This is to be
submitted electronically by running the script
/usr/class/cs248/bin/privsub from one of the myths.
The script will prompt you for the location of your writeup and the names and SUNet
IDs of your teammates. These submissions will be
held in the strictest confidence by the course staff.
The video game competition.
After the demos are finished, probably around 4:00pm (on December 3), a jury of
computer graphics experts from industry and academia will join the CS 248
teaching staff to evaluate your programs as part of a video game competition.
Any team may enter the competition; however, participation is not required.
The first step will be the selection of roughly 8 finalists. This selection
will be performed by the teaching staff immediately following the completion of
demos. The second step is the selection of prizewinners, which will be
performed by the jury. The composition of the jury will be announced shortly.
There will be one grand prize - an
all-expenses-paid trip to Siggraph 2009
in New Orleans next summer, and one second-place prize -
dinner for two at Il Fornaio
in Palo Alto. In addition, every member of a finalist team will receive a
current video game title for the PC platform, generously donated by Electronic
Arts. Finally, there will also be a special prize given for the wackiest or
most daring submission, but we don't yet know what it will be. (An Xbox was
last year's prize in this category.) Depending on the number of entries on
mobile platforms, we may create a special category of competition and prizes
for them, but this has not yet been decided. If the grand prize is won by a
team, it must be split among the team members. The second-place prize will be
duplicated as necessary to cover the team. Only one prize for wackiest
submission will be awarded. The competition will be accompanied by an amazing
As a prerequisite to entering the video game competition, each team must create
a web page for their project. The page should have a title, a paragraph
describing the game, and links to one or more screen-shots. The links to the
full-size screen shots should be by clicking on downsized versions of these
images, each 128 pixels tall. After the competition, entrants will be asked to
provide compressed "tar balls" or zip files for distribution of their game,
along with an indication of the target platform. The distribution should
include an executable for at least one platform. Any team that does not wish
to enter the video game competition but would like their game distributed is
also encouraged to create such a web page. Teams who do not enter the
competition do not need to create one.
Good luck, and have fun!
Copyright © 2008 Marc Levoy
November 20, 2008 06:35:54 PM