Assignment 3 Writing OpenGL program

School of Computing
CS3241 Computer Graphics 
Lab Assignment 3

LEARNING OBJECTIVES
Writing OpenGL program to simulate planar reflection using texture-mapping and a multipass rendering technique. After completing the programming assignment, you should have learned
how to
 set up texture mapping in OpenGL,
 model and draw texture-mapped objects,
 set up off-center view frustum,
 read back image in framebuffer for texture mapping, and
 simulate planar reflection using a multi-pass rendering technique.
TASKS
Please download the ZIP file Lab3_todo_(*).zip from the Assignments folder in LumiNUS Files.
You are to complete an incomplete C++ application program, so that it can simulate planar
reflection, using a multi-pass rendering technique and the texture-mapping capabilities provided by
OpenGL. You have to complete the program according to the following requirements.
Task 1
You have to complete main.cpp to produce the planar reflection that you see in the following
sample images:
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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.
The 3D scene contains a table with a flat rectangular semi-reflective table-top. The scene is also
populated with other objects, at least some resting on the table-top. The table-top must reflect the
scene. Here are some additional requirements:
 The reflection on the table-top is created by texture mapping a reflection image onto the tabletop rectangle. The reflection image is generated by drawing the scene seen from an imaginary
viewpoint, which looks through the table-top from under the table. This rendered image is then
copied from the color buffer to a texture object, to be used for texture mapping the table-top
rectangle.
 The reflection on the table-top should not be 100% (it is not a perfect mirror), and the underlying
diffuse color and lighting on the table-top must still be visible. (Hint: use the correct texture
function/environment.)
 Mipmapping must be used for all texture mapping, including for the reflection texture mapping.
For the texture object that contains the texture image copied from the color buffer, you have to
set the texture object using
glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
 You are not allowed to use the stencil buffer for this assignment.
 Write your code immediately below the locations marked “WRITE YOUR CODE HERE”. There
are three of such locations.
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 You are allowed to modify only main.cpp. You are not required and must not change any other
source files.
Task 2
In addition to the given teapot and sphere, you have to add at least one new texture-mapped object
into the scene. The new object(s) should be positioned above the table-top, and can float in the air.
You may not use the 3D models in the GLUT library (e.g. glutSolidTorus()) for your new
object(s), and must write your own function(s) to provide the polygons, vertex normal, texture
coordinates, and material. Each new object must have at least 4 polygons.
You are allowed to modify only main.cpp. You should use your own new image(s) to texture-map
your new object(s). As before, mipmapping must be used for all texture mapping.
Besides your completed main.cpp, you also need to submit the new texture image(s).
This task will be assessed based on the fulfillment of the basic requirements, on the technical
difficulty and object’s complexity, and on the aesthetics and creativity.
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 table’s height is changed, the reflection
from the table-top should still look correct.
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) and what is provided in the ZIP file, 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 8% of your total
marks for the module. The marks are allocated as follows:
 Task 1 –– 70 marks
 Task 2 –– 30 marks
 20 marks –– basic requirements,
 5 marks –– technical difficulty and object’s complexity,
 5 marks –– aesthetics and creativity.
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 that contains code for both Task 1 and Task 2;
 File(s) of your new texture image(s) for Task 2. They must be in the images subfolder.
Total image files’ size must not exceed 5 MB.
You must put it/them in a ZIP file and name your ZIP file nus-user-id_lab3.zip. For example, if
your NUS User ID is e0123456, you should name your file e0123456_lab3.zip.
Note that you may be penalized for submitting non-required files.
Submit your ZIP file to the Lab 3 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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