Recursive Drawing

Context Free Design Grammer is a context free grammer that describes shapes. Recursion is allowed as long as it terminates or becomes infinitely small. Hilarity and amazing designs ensue...

Mac OS X, Linux, Windows

Scheming Tortoises

Scheme is a powerful language, and you can have a lot of fun with very little code. Guile is a GNU scheme library for extending applications (think emacs lisp). One of the tutorials is building a simple Logo application (Guile Tortoise Tutorial). This has been "ported" to Cocoa/XCode (GuileTortoise.xcode), so that you can play with it on Mac OS X if you install guile. I recommend DarwinPorts, make sure that you get the 1.1 distribution if you are running 10.4.

Its simple to make some fun designs:




(define (rand-normal avg dist)
(lambda () (inexact->exact (+ avg (* dist (random:normal))))))

(define (rand-uniform max)
(lambda () (random max)))

(define (const x) (lambda () x))

(define (crazy-walk turn-thunk move-thunk)
(tortoise-turn (turn-thunk))
(tortoise-move (move-thunk)))

(define (punctuated-crazy-walk turn-thunk move-thunk)
(tortoise-penup)
(tortoise-move 2)
(tortoise-pendown)
(crazy-walk turn-thunk move-thunk))

(define (go count walk-func turn-thunk move-thunk)
(if (> count 0)
(begin (walk-func turn-thunk move-thunk)
(go (- count 1) walk-func turn-thunk move-thunk))))

(tortoise-reset)
(go 5000 punctuated-crazy-walk
(rand-uniform 360)
(rand-normal 5 1))