Assignment 2 OpenGL viewing,

School of Computing
CS3241 Computer Graphics 
Lab Assignment 2

LEARNING OBJECTIVES
OpenGL viewing, OpenGL transformations, hierarchical modeling, and animation. After
completing the programming assignment, you should have learned
 how to set up the view transformation (camera position and orientation) in OpenGL,
 how to set up perspective viewing in OpenGL,
 how to use the OpenGL transformations for modeling, and
 how to use the OpenGL transformations for animation.
TASKS
Please download the ZIP file Lab2_todo_(*).zip from the Assignments folder in LumiNUS Files.
You are provided with an incomplete C++ application program main.cpp, and your job is to
complete it according to the requirements.
You may try the completed executables: main_done.exe (for Windows), and main_done (for
macOS) found in the same ZIP file. (On macOS, you may need to use the command sudo chmod
+x main_done to give the file execute permission before running it.)
Please read the instructions shown in the console/terminal window to learn how to operate the
program. When you run the program, you should see a spherical planet at the center of the window.
There are a dozen cars moving on the planet surface, and each car moves in a different great circle
(you can search the web to find out what a great circle is), and they have different speeds and colors.
You may try the followings on the program:
 resize the window and see what happens,
 press the Up, Down, Left or Right arrow key to change the camera’s position,
 press the Page Up or Page Down key to change the camera’s distance from the planet,
 press the ‘P’ key to pause/resume the animation of the cars.
You will notice that the camera is always looking at the center of the planet. With respect to the planet,
the camera’s position can be expressed as latitude and longitude, and its distance from the planet’s
center. When the Left or Right arrow key is pressed, the camera’s longitude decreases or increases,
respectively; and when the Down or Up arrow key is pressed, the camera’s latitude decreases or
increases, respectively. Note that the camera’s up-vector is always pointing north.
National University of Singapore 2 / 4 School of Computing
Figure 1
Follow the following instructions to complete main.cpp as required. You must not add or change
any other files.
1) Study the source program very carefully.
2) Complete the DrawOneCar() function. The function must draw the car using only GLUT
functions such as glutSolidCube(), glutSolidTorus(), glutSolidCone(), and
glutSolidSphere(). You should not directly use any OpenGL geometric primitive. You
should make use of the OpenGL 3D transformation functions to help you resize, orientate and
position the parts. The functions glPushMatrix() and glPopMatrix() are very helpful for
you to save and restore the current transformation before and after drawing each part. You can
design your cars any way you like as long as they look like cars. More details about the GLUT
functions can be found at https://www.opengl.org/resources/libraries/glut/spec3/spec3.html.
3) Complete the DrawAllCars() function. This function draws each car at the correct position on
its great circle. Note that any great circle on a sphere centered at the origin can be defined as
follows. Let C be the great circle in the y = 0 plane, and let v be a vector in the x-z plane, and let
 be an angle. If we rotate C about v by , we get another great circle of the sphere. All great
circles of the sphere can be obtained by varying v and .
4) Set up the correct perspective viewing volume in the MyDisplay() function. You should use the
gluPerspective() function. The near and far planes should be set near the planet’s surface,
yet still do not clip off any part of the planet and cars. The near and far planes should vary with
the eye’s distance from the planet’s center. You should make use of the value of the predefined
constant CLIP_PLANE_DIST to position your near and far planes.
5) Set up the correct view transformation (camera’s position and orientation) in the MyDisplay()
function. You may use the gluLookAt() function, or you can use an alternative method.
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6) Complete the MyTimer() function. You should use the GLUT timer callback to control the speed
of the animation by maintaining a constant frame rate (DESIRED_FPS). Refer to
https://www.opengl.org/resources/libraries/glut/spec3/node64.html to find out more about the
GLUT function glutTimerFunc().
More detailed instructions can be found in the unfinished program code. You may add additional
constants, global variables and functions to the given program.
DO NOT HARD-CODE VALUES. You should write your code in such a way that when the values
of the named constants (defined in the beginning of the program) are changed to other valid values,
your program should function accordingly. For example, if the car’s size is changed, the tyre size
should vary proportionally.
A Visual Studio 2017 solution main.sln (or Xcode project main.xcodeproj on macOS) is provided
for you to build the executable program. In this assignment, you are not required and must not
change any other C/C++ source files besides main.cpp.
Besides GLUT (or FreeGLUT), you should not use any other third-party libraries. Your code must
compile with either the MSVC++ 2017 (or newer) compiler on Windows, or Clang on macOS.
GRADING
The maximum marks for this programming assignment is 100, and it constitutes 7% of your total
marks for the module. The marks are allocated as follows:
 30 marks — drawing of a car in the DrawOneCar() function.
 30 marks — putting each car at its correct position on its great circle in the DrawAllCars()
function.
 10 marks — setting up the correct perspective viewing volume with tight and varying near
and far planes.
 25 marks — setting up the correct view transformation (camera’s position and orientation).
 5 marks — correct MyTimer() function.
Note that marks will be deducted for bad coding style. If your program cannot be compiled and linked,
you get 0 (zero) mark.
Good coding style. Comment your code adequately, use meaningful names for functions and
variables, and indent your code properly. You must fill in your name, and NUS User ID in the header
comment.
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SUBMISSION
For this assignment, you need to submit only your completed main.cpp.
You must put it/them in a ZIP file and name your ZIP file nus-user-id_lab2.zip. For example, if
your NUS User ID is e0123456, you should name your file e0123456_lab2.zip.
Note that you may be penalized for submitting non-required files.
Submit your ZIP file to the Lab 2 Submissions / Group T0x folder in LumiNUS Files, where T0x
is your officially allocated Tutorial group number. Before the submission deadline, you may upload
your ZIP file as many times as you want to the correct folder. We will take only your latest
submission. Once you have uploaded a new version to the folder, you must delete the old versions.
DEADLINE
Late submissions will NOT be accepted. The submission folder will automatically close at the
deadline.
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