Step 2(b): Framework and source code

By itself, OpenGL doesn't make it possible to write complete programs. At the very least, it needs a way to talk to the computer's window system. And of course, there are numerous libraries, toolkits, and frameworks that we can layer on top of OpenGL to make coding easier. For this course we seek a middle ground: enough infrastructure to help you get started, without hiding the technical details of OpenGL programming. We're using the following:

• C++
• gl3w, a low-level system that provides access to the official OpenGL API.
• GLFW, a simple framework that wraps an OpenGL context inside a window and manages user events.
• GLM, a mathematical library for the parts of linear algebra needed in computer graphics. Conveniently, it mimics the types and features of GLSL, the shader programming language used with OpenGL.
• ImGui, a user interface toolkit.
• cs488-framework, a thin layer on top of the libraries listed above.

To avoid potential problems with missing libraries or incorrect versions, you will download a package from us that contains the source code for all these libraries, bundled with skeleton code for the Assignments.

To begin, download the file cs488-s2022.zip and unzip it to create a cs488/ directory. The bundled libraries are all in shared/. You shouldn't need to change anything in that directory. The assignments can be completed by writing code in the A0/, A1/... directories.

Currently, our premake4 files specify that the code will be compiled with C++14. If you prefer to use c++17, then edit premake4.lua and change "-std=c++14" to "-std=c++17" in the build options. You will need to do this in the cs488/ directory as well as the assignment directories (e.g., A0/, A1/, etc.). Contact the instructor if you wish to use another C++ standard other than 14 or 17.

Now build the bundled libraries. They have different build processes, but we've provided a quick way to get it all done at once:

  $ cd cs488
  cs488$ premake4 gmake
  cs488$ make

(You'll need to have premake4 and cmake installed on your system.)

Step 3: My First Triangle

Now go into the A0/ directory, build the skeleton code, and run it:

  $ cd A0
  cs488$ premake4 gmake
  cs488$ make
  cs488$ ./A0

You'll see a window with a single white triangle and a small palette in the corner with user interface controls.

Make the following changes to the program, all in A0.cpp:

1. Initially, the Quit Application button is placed underneath the Red Channel slider. Move it so that it's the first control in the Shape Properties palette. Also, add a keyboard shortcut: the Q key should quit the program.
2. Add two new sliders to Shape Properties: a Green Channel and a Blue Channel. Taken together, the three sliders should give you complete control over the RGB colour of the triangle.
3. Add a slider to control the rotation angle of the triangle (there's already a rotation member variable in the A0 class that you can set). The slider should allow you to rotate the triangle through exactly one complete circle.
4. Add keyboard shortcuts to scale the triangle (again, use the defined member variable). Use the - (minus) key to scale down by a constant factor, and the + (plus) key to scale up by the same factor. Choose your factor so that the triangle scales at a reasonable rate.
5. Between the Quit button and the sliders, add a Reset button that sets the triangle back into its original state (colour, scale, rotation, position). Add a keyboard shortcut, so that the R key resets.
6. Take a screenshot of your finished program and store it as A0/screenshot.png.

Step 4: README

For programming assignments, you will be required to create a text file called README. Place your README file in the A0/ directory. The README file should contain two sections:

• Compilation: Give short instructions on how to compile and run the program. Indicate if there are any changes relative to the default premake4/make combination. Mention any additional assumptions (for example, if the program must be run from a particular directory). Also mention that you tested your assignment on the VM (if we can't get your program running, we'll try it on the VM as a failsafe). If assignment features do not work on the VM, the assignment will not qualify for a re-mark even if it works perfectly on the host OS of your personal computer.

• Manual: The manual is not a restatement of the assignment specification: we know what the program is supposed to do. The manual should include any details or assumptions that you have made that were not included in the specification. Tell us about any extra commands, options or features you added, or any additional data files that you may have generated. If you have made any assumptions about the assignment specification or the objectives, be sure you state and justify them here.

  You should also note in your manual any objectives that you did not complete. If you wrote code for objectives that you did not get completed, you may request code credit in your manual.

Step 5: Submitting your program

In most assignments, you'll need to upload a directory of code. Create a ZIP file containing the A0/ directory and all its contents. Upload it to LEARN. If you want to be helpful, do a make clean in A0/ before zipping it up, to avoid including unneeded build files.

The proper way to create the A0.zip is to use the -r option. By default, the zip is not recursive. For example:

  $ cd cs488
  cs488$ zip -r A0 A0

We highly recommend that after submitting, you download your own A0.zip file, unzip it and and execute premake4 gmake and make again to make sure that everything compiles and builds as expected. For example, a left-over temp file named A0-backup.cpp will likely cause your submission to not build. Also be sure to test that your submitted A0 executes correctly and matches your expectations.

Take special care as your home machine may have a newer compiler. As such, code written at home may not compile on the virtual machine, especially if you make use of language features that are not available on the VM's compiler.

Step 5: Objective list

Every assignment includes a list of objectives. Your mark in the assignment will be based primarily on the achievement of these objectives, with possible deductions outside the list if necessary.