CS40 Intro

Wednesday | Friday
Fall 2018
Welcome to Computer Graphics! This course serves as an introduction to the area of graphics. We will learn many of the basics of modeling and rendering from a modern OpenGL approach. This course will feature lots of programming, and lots of math, but the math is not super complex. We will design many interesting projects, and you will have a chance to explore your own final project, but if you are expecting to design a full fledged 3D game, or the next CGI movie, this course will not meet your expectations. This course is designed around understanding core concepts and preparing you to explore more advanced topics in computer graphics.

An Overview of Computer Graphics

Connections to other Courses

Software Tools for this course

Math Concepts


Getting Started

We'll be using git to submit code electronically. Follow the instructions for setting up your Swarthmore Github Enterprise account.

Course examples

mkdir cs40
cd cs40
git clone git@github.swarthmore.edu:CS40-F18/examples-YOURUSERNAME.git examples
cd examples
git remote add upstream git@github.swarthmore.edu:CS40-F18/examples.git
git fetch upstream


Once you have a copy of the code, Build the examples with CMake
[examples]$ mkdir build
[examples]$ cd build/
[build]$ cmake ../
[build]$ make -j8
[build]$ cd w01-intro
[w01-intro]$ cd simpletests
[simpletests]$ ./helloCS40
Try running the other examples in the w01-intro folder
With CMake you compile, run, and test programs in the build directory. You edit source files outside of the build directory. You may want to have one terminal window open for running programs, and a separate terminal for editing.
You can use the Git overview page to review basic git usage. If you have questions, chances are other students do too. Please post in Piazza to start a discussion. You can post anonymously to the rest of the class (but not to the instructor).

Using Qt

OpenGL is the primary language for creating images from 3D models, but OpenGL is primarly focused on just that: image creation. Often we want more interactive applications, perhaps with buttons, menus, and key bindings. To get those features, and additionally an OpenGL context, we will be using the Qt (cute) framework to develop Graphical User Interfaces (GUIs). Keep in mind the focus of this course is on the graphics aspects, but having a basic working GUI is nice too. We won't be UX experts by the end of this course, but Qt is modern and actually used by some companies.

Let's walk through the creation of simple Qt application and demonstrate qtcreator. For more details, see the qt demo page.


Required Reading

Optional Reading

Up late wondering how the signals and slots mechanism in Qt5 is actually implemented and can't fall asleep? These readings might not answer all your questions, but they should help you sleep better. These readings are entirely optional.

QT and OpenGL

The class QOpenGLWidget creates an OpenGL context inside QT. OpenGL functions are called within this context. Additionally, QT has some OpenGL wrapper classes beginning with the prefix QOpenGL.

Creating a QT OpenGL application

We store the vertices of a triangle in a VBO in GPU memory. The next step is to define, create, load, and compile shaders. The vertex shader runs first and takes vertex data from the VBO and outputs geometry in clip coordinates. This geometry is then clipped, rasterized, and fed to the fragment shader which runs on each fragmenet, or potential output pixel. The output of the fragment shader is written to a framebuffer and displayed in the viewport. Once each shader is compiled, we define, create, and link a shader program, which is the combination of a vertex shader and a fragment shader. Finally, we are ready to draw. The main steps are: Once the geometric data are copied to GPU memory, almost everything else happens on the GPU. paintGL is just issuing commands to the GPU. The GPU itself will process those commands.