GoLfind

Finding Game of Life states that eventually turn into a picture, such as the Mona Lisa.

Write-up: https://kevingal.com/blog/mona-lisa-gol.html

Comes with code for simulating Life, doing backsearch (i.e. finding the parent state of a Life state) and creating GIFs / animations of the Life simulation. Even if you haven't used Common Lisp before, it should be straightforward to follow the examples (below) and play around with it.

I created a tool for converting images to black & white, which might come in handy if you want to Life-ify your own pictures.

Setup

Step 1: prerequisites

You'll need:

• An implementation of Common Lisp.
• Quicklisp (the Common Lisp package manager).

If you don't have these, the fastest way to get started is to install Portacle, which comes with everything you need.

Step 2: download

Clone this repository into your Quicklisp local-projects folder. For Portacle users, this should be ~/portacle/all/quicklisp/local-projects/.

$ cd ~/portacle/all/quicklisp/local-projects/
$ git clone https://github.com/Kevinpgalligan/GoLfind.git

Step 3: manual sketch installation

The sketch library requires a manual installation step, unfortunately. You'll need to install some SDL2-related dependencies, as described in its README. Shortcut for Debian users: sudo apt-get install libsdl2-dev libsdl2-ttf-dev libsdl2-image-dev.

Step 4: load

From within your REPL, run (ql:quickload 'golfind). You should now be able to play with the examples below.

If anything doesn't work or you're confused by these instructions, please let me know and I'll try to help.

Usage examples

From the REPL...

CL-USER> (in-package golfind)
#<PACKAGE "GOLFIND">
GOLFIND> (defparameter custom-life
    (life-from-lists (list (list LIVE DEAD)
                     (list DEAD LIVE))))
CUSTOM-LIFE
GOLFIND> custom-life
#S(LIFE :GRID #2A((T NIL) (NIL T)) :ROWS 2 :COLS 2)
GOLFIND> (defparameter some-life (random-life 4 4))
SOME-LIFE
GOLFIND> some-life
#S(LIFE
   :GRID #2A((T T NIL NIL) (NIL T NIL T) (NIL T T NIL) (NIL T T T))
   :ROWS 4
   :COLS 4)
GOLFIND> (life-get-cell some-life 0 1)
T
GOLFIND> (life-get-cell some-life 0 2)
NIL
GOLFIND> (defparameter next-life (life-next-state some-life))
NEXT-LIFE
GOLFIND> next-life
#S(LIFE
   :GRID #2A((NIL NIL NIL NIL)
             (NIL NIL NIL T)
             (NIL NIL NIL NIL)
             (NIL NIL NIL T))
   :ROWS 4
   :COLS 4)
GOLFIND> (find-life-parent-state next-life)
[...trimmed MiniSAT output...]
Memory used           : 7.43 MB
CPU time              : 0.024131 s

SATISFIABLE
[...trimmed MiniSAT output...]
#S(LIFE
   :GRID #2A((NIL NIL T NIL) (NIL NIL NIL NIL) (T NIL NIL T) (NIL NIL NIL NIL))
   :ROWS 4
   :COLS 4)
T
GOLFIND> ; the parent we found is different to some-life, next-life has multiple parents
; No value
GOLFIND> ; run an animation
GOLFIND> (run-life some-life :pixels-per-cell 50 :frames-per-state 20)
#<LIFE-ANIMATE {10036EE1D3}>
GOLFIND> ; load a black & white image as a Life state
GOLFIND> (defparameter pic-as-life (load-png-as-life "/home/kevin/Imágenes/gol.png"))
PIC-AS-LIFE
GOLFIND> pic-as-life
#S(LIFE
   :GRID #2A((NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL
              [...insert big-ass array here...]
   :ROWS 348
   :COLS 348)
GOLFIND> ; save it as a gif
GOLFIND> (life-to-gif pic-as-life "~/mygif.gif" :num-states 5 :pixels-per-cell 3)
#P"/home/kevin/mygif.gif"