[Larceny-users] gl/glut milestone: rendering CFDG models

[Eduardo Cavazos]

Hello,

ContextFree is a program which renders pretty pictures given programs 
expressed in a very concise language:

     http://www.contextfreeart.org/

Here is one such example:

     http://www.contextfreeart.org/gallery/view.php?id=541

I implemented the ContextFree semantics and rendering system. Here's a 
screenshot of Ypsilon executing such a rendering:

     http://proteus.freeshell.org/ypsilon-chiaroscuro.png

Note, this is a pure Scheme implementation; I'm not depending on the 
ContextFree code at all.

I'm mentioning it here because the demo also runs in Larceny, unchanged.

A very sketchy early implementation is here:

     http://proteus.freeshell.org/_cfdg-window-a.scm

Here's an example of embedding cfdg rules in Scheme. Here's some code 
from the original chiaroscuro rendering:

----------------------------------------------------------------------
rule BLACK 60 {
     CIRCLE {s .6}
     BLACK {x .1 r 5 s .99 b -.01 a -.01}
}
rule BLACK {
     WHITE {}
     BLACK {}
}
----------------------------------------------------------------------

The following is an explicit representation of what's going on. It's 
much longer than the cfdg syntax; an opportunity for syntax-rules. :-)

----------------------------------------------------------------------
(define (black)
   (when (iterate?)
	(call-random-weighted
	 (vec
	  (vec 60 (lambda ()
		    (block
		     (lambda ()
		       (size 0.6)
		       (circle)))
		    (block
		     (lambda ()
		       (x 0.1)
		       (rotate 5)
		       (size 0.99)
		       (brightness -0.01)
		       (alpha -0.01)
		       (black)))))
	  (vec 1 (lambda ()
		   (block
		    (lambda ()
		      (white)
		      (black)))))))))
----------------------------------------------------------------------

Anyway, I just wanted to share this milestone; the first rendering 
happened about 10 minutes ago. :-)

The code's very sketchy. I'll share a cleaned up version.

Ed