What Links Here?
Penrose Tiling
A famous non-repeating tiling pattern, invented (discovered.) by Roger Penrose, a giant in the worlds of mathematics and floor-coverings.
The following logo program produces a penrose tiling. I found this at http://logo.twentygototen.org/E3_yJcQ4.
I haven't looked through it enough to understand it. I can only marvel at its wondrousness.
;; PENROSE TILING IN LOGO ;; ; Now with comments and constants, granted from ; actually looking at the syntax. Feel free to ; poke around. ;;;;;;;;;;;;;;; ;; CONSTANTS ;; ;;;;;;;;;;;;;;; ; Brush constants make "kite_col [220 25 20] make "dart_col [12 12 20] make "pwidth 2 ; Shape constants make "startx 20 make "starty 480 make "size 10 make "detail 9 ; Golden ratio make "phi 1.61803399 make "phi_inv 0.61803399 ;;;;;;;;;;;;;;;;; ;; SUBROUTINES ;; ;;;;;;;;;;;;;;;;; ;; DRAW A HALF-KITE, WITH DEFLATION ;; to hkite :depth :dir ifelse :depth > 1 [ ; Deflation case ; reduce recursion depth make "depth :depth-1 ; Draw components and return to origin turn :dir 36 hdart :depth (not :dir) turn (not :dir) 36 fw (power :phi :depth) * :size rt 180 hkite :depth (not :dir) turn (not :dir) 72 hkite :depth :dir turn :dir 72 fw (power :phi :depth) * :size rt 180 ] [ ; Base case ; Draw half kite and return to origin pd color :kite_col fw :size turn :dir 108 fw :size*:phi_inv pu turn :dir 108 fw :size turn :dir 144 ] end ;; DRAW A HALF-DART, WITH DEFLATION ;; to hdart :depth :dir ifelse :depth > 1 [ ; Deflation case ; reduce recursion depth make "depth :depth - 1 ; Draw components and return to origin hkite :depth :dir fw (power :phi :depth) * :size turn :dir 144 hdart :depth :dir turn :dir 36 fw (power :phi :depth) * :size rt 180 ] [ ; Base case ; Draw a half-dart pd color :dart_col fw :size turn :dir 144 fw :size*:phi_inv pu turn :dir 72 fw :size*:phi_inv turn :dir 144 ] end ;; PARAMETRISED RT/LT ;; to turn :dir :angle ifelse :dir [rt :angle] [lt :angle] end ;;;;;;;;;;;;;;;;;; ;; MAIN PROGRAM ;; ;;;;;;;;;;;;;;;;;; reset ; Initialize setxy :startx :starty penwidth :pwidth ; Draw a single kite, deflating as required hkite :detail true rt 72 hkite :detail false