From 2006 IOCCC (International Obfuscated C Code Contest).

See refactor branch for untangled version or follow along with the video on Craft vs Cruft YouTube channel.

Homer's Favorite

Andy Sloane

Judges' Comments:

To build:

    make slone

To run:

    ./sloane

Looks almost good enough to eat, dunnit? I suppose you could argue that, at first blush, this looks like a self-reproducing program.

Selected Author's Comments:

This program doesn't require any special build options, other than that it uses sin and cos and hence requires the math library.

You will almost certainly get a compiler warning because I declared a bunch of global ints without types. The code looks better this way, though, I think. There are also no #includes, so there may be warnings for undeclared references to printf, etc. There's a chance that my failure to include math.h or declare sin or cos will make the donut not render properly -- it's worked on every system I've tried so far though.

You will need some kind of VT100-ish emulation; so while this compiles and runs OK in Windows, you will need PuTTYcyg or something like that.

The shape of the source gives a hint about its output: it's a little animation of a shaded donut rotating over an infinite checkerboard. Like many IOCCC entries, it is thus self-documenting.

I wanted to create something as "pure" as I could - meaning that the entire source code is shaped into a work of art, without being prefixed by any #define hacks, or even #includes, and is portable enough to not require any special libraries to do the animating. I achieved this with two standard escape codes for clearing the screen and moving the cursor back to the top-left.

The donut isn't raytraced. It's much simpler than that.

How is it obfuscated?

There are three main pieces to this program: the donut, the checkerboard, and the ASCII logo. The first two are programmed in a straightforward way (with z-buffering even!), but the mathematics for drawing them is "optimized". The ASCII logo has been shrunk into the smallest I could make it by any means necessary.

The logo can actually be compressed much better (ironically, by doing something simpler), but I didn't discover this until well after submitting.

Puzzles

In increasing order of difficulty:

• Can you change the shading of the donut and checkerboard?

• Can you change the movement rates of the donut, the checkerboard, and the scrolling logo?

• Can you change the inner/outer radii of the donut? The height/scaling of the checkerboard?

• How is the "IOCCC 2006" logo encoded? Can you put something else in its place? Can you find a smaller encoding?