CS 418 – MPs

1 Overview

Each MP has a point value, representing some combination of its difficulty and importance; and a category, either core or elective.

For full (100%) credit, you need to earn your credit-count enrollment times 10 core points and a like number of elective points. Thus, if you are enrolled for 3 credits you need 30 core and 30 elective points; if you are enrolled for 4 credits you need 40 core and 40 elective points. Excess core points count as elective points but excess elective points do not count as core points. Earning fewer than that many points may result in a lower grade, as outlined in the grading policy.

Why ×10?

The points on the assignments are my effort to estimate the hours I expect the median UIUC student will invest in meaningful programming, assuming they’ve already invested significant time in understanding course content. Given the federal definition of 1 semester credit hour = 45 hours of total educational time and assuming you use half1 of that with reading, viewing, quizzing, discussing, and reviewing content that leaves about 20 hours per credit of programming time, or 10 hours per credit of core MP and 10 hours per credit of elective MP.

There are two 0-point warm-up assignments. These walk you through code you’ll need in other MPs and ensure that your code works on the grading server; although we don’t grade them, students in past semesters asserted that they were very helpful and that submitting them before the MPs reduced their overall work.

There are 42 core points available.

Core MP Lang Notes
8 Rasterizer any You code a partial implementation of what WebGL does
2 Logo WebGL2 Basic motion
4 Orbits WebGL2 Scene graph
8 Terrain WebGL2 Generate and render geometry
4 Flight WebGL2 Let the user move the camera
4 Textures WebGL2 Basic texture maps
8 Raytracer any Implement a basic raytracer
4 Spheres WebGL2 Simulate motion using simple physics

The Rasterizer will help you understand WebGL2 and should be completed first, followed by Logo. Terrain is a prereq to both Flight and Textures. Otherwise the order is not important, but we recommend the order listed here.

There are more than 80 elective points available; you only need 30 or 40 of them, depending on your credit enrollment.

Elective MP Lang Notes
0–20 Rasterizer any additions to the core Rasterizer
2 Psychedelic WebGL2 visualize colorful time-varying functions
2 GPU jitter WebGL2 simple vertex shader added to Logo
3 CPU jitter WebGL2 simple dynamic positions added to Logo
2 Lineograph WebGL2 keyboard motion without clearing
2–4 OBJ loading WebGL2 load a common file format
2–4 Parametric WebGL2 generate spheres and toruses
4 Subdivision WebGL2 subdivide after OBJ Loading
1 Cliffs WebGL2 variant of core Terrain styling
2 Weathering WebGL2 variant of core Terrain modeling
3 Height map WebGL2 variant of core Terrain styling
4 Drive WebGL2 variant of core Flight
1 Fog WebGL2 variant core Flight rendering
0–26 Raytracer any additions to the core Raytracer
4 Many spheres WebGL2 more efficient and versatile variant of core Spheres
4 Goop WebGL2 smoothed particle hydrodynamics based on Many spheres

2 Extensions

Deadlines have two purposes: to help you manage your time and to give us have enough time to grade your work.

Before a deadline comes due, you can extend it by going to the submission page and entering an extension request. These are routinely granted without further review, but too many extensions (especially near the end of the semester) can create a grading burden we can’t handle and may result in some being rejected. For that reason, please provide your rationale in the request.

The only notification of a successful extension request is a changed deadline on the submission page. Rejected requests are communicated via campuswire DMs.

3 Regrades

There are four types of regrade requests:

Grading errors
If we mis-graded your submission, let us know in a to-instructors post on campuswire and we’ll address it.
Server errors
If your code works for you but not for us, let us know in a to-instructors post on campuswire. We’ll investigate and may fix our server, ask you to fix your code, or explain why your code doesn’t really work (the latter changing this to a different type of regrade).
Incorrect core MP

The core (parts of) MPs are selected because they represent content we want every student to master. If you lost core points during grading, you should

  1. Understand why they were lost (either by inspection or by visiting office hours)
  2. Fix your code
  3. Request (in a to-instructors post on campuswire) a chance to re-submit the assignment with the fixed core part
Fewer elective points than you wished
Our advice here is focus on the upcoming assignment instead. Elective points are one big pool, so if you missed a point on one but do another point on the next it will come out at 100% in the end. There may be some special cases where we re-open an assignment to have elective points fixed, but we expect that to be rare.

4 Makefile

Some MPs allow you to code in any language you want. We support that by using GNU Make as a build tool. There are many newer build tools out there, but make remains the most widely deployed.

For these MPs, we execute your code as follows:

  1. Enter the directory containing your code
  2. Run make build
  3. For each input file we want to test (for example mp9xyzw.txt),
    1. Copy the input file (mp9xyzw.txt) into the directory
    2. Run make run file=mp9xyzw.txt or the like
    3. Move the output file elsewhere, diff it against our expectations with ImageMagick, etc

The first warmup gives example Makefiles for many languages. If you know about Makefiles you are welcome to make your own, but for most students our example files can be used as-is.

If you don’t have make on your computer, you can either install it or test without it.

4.1 Installing make

Almost every OS

Either comes with make installed or allows installing it through the package manager under the name make

This is true of at least Arch, Gentoo, Fedora, SUSE, CentOS, Nix, Guix, Debian, FreeBSD, OpenBSD, NetBSD, and Haiku; as well as their various re-skinned wrappers like Manjaro, Mint, Ubuntu, etc.

MacOS

Students have had success with each of the following (pick one):

Windows

Students have had success with each of the following (pick one):

4.2 Testing without make

The Makefiles provided in the first warmup have two lines they run.

The basic structure of a Makefile is

rulename: optional dependencies
    code to execute

When we run make rulename it first looks for any rules named after dependencies and runs them; then it runs the code. While doing this it expands any names between $( and ) with their definition; notably, it expands $(file) with an input filename like mp1req1.txt.

Suppose a makefile contains

run: program
    ./program $(file)

program: main.cpp
    clang++ -O3 -I. main.cpp -o program

Then running make run file=demo.txt will first make program; because main.cpp is not a rule in the Makefile the dependency chain stops there; it will jump to the command under program:, and then do the command under run:, for a final operation of

clang++ -O3 -I. main.cpp -o program
./program demo.txt

Thus running those two commands directly will test your code without needing make.

Several example Makefiles have

build:
     

There’s no dependencies and no commands, so running make build does nothing. This is common for interpreted languages like Python.

5 WebGL2 Dialect

Some MPs will require you to write in WebGL2. We will impose a variety of limitations on these MPs beyond what the WebGL2 api and JavaScript and GLSL languages themselves imposes.

  • No WebGL warnings.

    The only exception to this is WebGL-generated warnings responding to invalid user input, such as user-specified file names that do not exist on the server.

  • Browser-agnostic.

    The V8 JavaScript engine (used by Chrome and Edge) applies some default values that can make certain kinds of erroneous code work when it is small but break when you add more to it. To avoid those cases, we will test on Firefox, LibreWolf, PaleMoon, or another Gecko-based browser, and we recommend that you do too.

  • Various do it this way rules for things WebGL2 lets you do several ways.

    These serve two purposes. First, they help protect you from practices that we’ve notices tend to work at first but then lead to tricky-to-diagnose errors later on. Second, they help the course staff understand your code.

    We have a separate page describing the specific rules and offer a wrapWebGL2.js script that checks these rules for you and generates warnings if they are violated.