Escher in Lisp
Sunday, February 13, 2005
Frank Buss
commented on c.l.l. how he never really understood how to use higher order functions as combinators,
until he read the
article from Peter Henderson about Functional
Geometry. He has written
his own article about how he used these concepts and Common Lisp to re-create the famous
recursive fish drawing by
M.C. Escher. The Henderson approach will be familiar to those who have read the
"Picture Language" example in
SICP (see also the
video - Lecture 3a).
Frank's
code outputs a Postscript file. Rainer Joswig did a
CLIM
version of the Lisp code and Geoffrey Summerhayes did a
LispWorks CAPI version. Since I've been fascinated by Escher's
work for many years, I downloaded the code and had a play with
it on my iMac. The screenshot below shows Frank's and Geoffrey's
versions. The only mod I made was to the "plot" function in Frank's
code (he hardcoded in some Win32 file locations which I "treaked" for
the Mac).
