Cody Boone Ferguson
cbf87ab40d
This video unfortunately comes from YouTube and so even if the link eventually dies we should not have it here. A link was provided. Updated the .entry.json and manifest in the index.html plus checked other formatting issues.
114 lines
3.6 KiB
Markdown
114 lines
3.6 KiB
Markdown
## To build:
|
|
|
|
``` <!---sh-->
|
|
make
|
|
```
|
|
|
|
|
|
## To use:
|
|
|
|
``` <!---sh-->
|
|
./eastman
|
|
```
|
|
|
|
**NOTE**: to restore your cursor in your shell, try `reset`.
|
|
|
|
|
|
## Try:
|
|
|
|
Run the program. Quit it (ctrl-c/intr). Resize your terminal window. Run it
|
|
again. Try doing this a number of times with different sizes each time.
|
|
|
|
``` <!---sh-->
|
|
./eastman
|
|
```
|
|
|
|
**NOTE**: to restore your cursor in your shell, try `reset`.
|
|
|
|
|
|
## Judges' remarks:
|
|
|
|
This round program will generate a classic spherical result!
|
|
|
|
You will need a terminal capable of displaying coloured ANSI
|
|
characters (for example an xterm or a Terminal.app window in macOS).
|
|
|
|
You might also want to turn off any scrollback history. The program will
|
|
size itself to the initial geometry of your terminal.
|
|
|
|
If you are ambitious, make the font really small and the window really
|
|
large for hi-res graphics!
|
|
|
|
|
|
## Author's remarks:
|
|
|
|
This program uses ANSI graphics to recreate the classic Boing Ball demo from
|
|
the Commodore Amiga. See <https://www.youtube.com/watch?v=-ga41edXw3A> if you
|
|
aren't familiar with it. Back in its day, this demo inspired lust and awe in
|
|
geeks around the world.
|
|
|
|
The graphics are
|
|
[raytraced](https://en.wikipedia.org/wiki/Ray_tracing_(graphics)), with
|
|
procedural textures on the ball and the back wall. I did cheat a little to
|
|
simplify the calculations: it uses a parallel projection, but textures the back
|
|
wall to look as if there were a floor being viewed in perspective. The shadow
|
|
is also just part of the texture, not an actual raytraced shadow.
|
|
|
|
This program automatically adapts to the size of the terminal it is running in,
|
|
so try enlarging the window to get higher resolution. Don't resize while the
|
|
program is running, though. It only checks the size once, when it starts up.
|
|
|
|
To compile:
|
|
|
|
``` <!---sh-->
|
|
cc -lm eastman.c
|
|
```
|
|
|
|
|
|
### Portability
|
|
|
|
It should be completely portable. I've tested with gcc on Mac OS X 10.7 (Lion)
|
|
and Fedora 10. I would expect it to work in any Unix-like environment.
|
|
|
|
|
|
### Obfuscation
|
|
|
|
I have merged expressions wherever possible, making extensive use of ternary
|
|
operators, commas, return values of assignment operators, etc. The entire
|
|
raytracing computation, include ray intersection tests and procedural texture
|
|
evaluations, is a single expression involving 41 operators.
|
|
|
|
Variables are named alphabetically in the order they are declared.
|
|
|
|
The third argument to `ioctl(2)` should really be a `struct winsize`, and I
|
|
should then look up the `ws_row` and `ws_col` fields, but that makes it way too
|
|
obvious what I'm doing there. Since a `struct winsize` just contains four
|
|
`unsigned short`s, I replaced it with an array. And since all the values will
|
|
be much less than `32767`, I further simplified the type to just `short[]`.
|
|
|
|
A wonderful thing about ANSI graphics is that it produces nearly unintelligible
|
|
code. Consider the `printf(3)` spec to print a single space in a desired color:
|
|
`"\x1B[%dm `. I could have done something to further obfuscate it, but it's
|
|
already indistinguishable from line noise, so why bother?
|
|
|
|
There are lots of other minor obfuscations to make the code less obvious. For
|
|
example, I could have written the outer loop as `while(1)`, but why write a 1
|
|
when I can calculate it from the return value of `usleep(3)` instead? And I
|
|
could have written `usleep(80000)`, but `usleep(79383)` just looks so much
|
|
better. And so on.
|
|
|
|
|
|
<!--
|
|
|
|
Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
|
|
|
|
You are free to share and adapt this file under the terms of this license:
|
|
|
|
Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
|
|
|
|
For more information, see:
|
|
|
|
https://creativecommons.org/licenses/by-sa/4.0/
|
|
|
|
-->
|