;;; arabesque.nlogo, cr 16 apr 2006 by rha on hypatia
;;; imitate john whitney sr pascal code
;;; with verbose comments 15 jan 2008 by rha on thales2

;;;;;;;;;;;; interface;;;;;;;;;;;
;;; usual three buttons (go is forever) and graphics window:
;;;	torus 35 x 35, origin in center, 12 x 12 pixel patches
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

globals [ mylist ] ;;; global variable declaration is a list of one 

to setup ;;; the setup button calls this procedure
  ca ;;; clear-all, resets everything
  set mylist n-values 360 [?] ;;; initialize the sole global variable
       ;;;;;;;; NOTE: mylist is initialized as a list of natural numbers 0,...,259
       ;;;;;;;; read about "n-values" in the NetLogo Dictionary
  crt 360 ;;; create 360 random turtles
  foreach mylist [   ;;; traverse my list and apply to each of its numbers ---
    ask turtle ? [     ;;; for each n ask turtle n to run three turtle commands
      set color red
      set heading ? ;;; here "?" means the number of the turtle (so turtles radiate)
      forward 15      ;;; makes a circle of turtles or radius 15 (almost fills the graphics window)
      ]                     ;;; end of inner group (ask)
    ]                       ;;; end of outer group (foreach)
end   ;;;;;; end of setup procedure

to step ;;; the step button calls this main procedure
  let stepsize 0.01 ;;; NOTE the special word "let" declares a local variable (and sets it)
  foreach mylist [  ;;; as above
    ask turtle ? [    ;;; as above
      set heading 90 ;;; right-angle turn clockwise
      forward ? * stepsize ;;; size of move ahead is turtle number times stepsize
      ]
    ]
end

to go ;;; the go (gorever) button: one press calls step repeatedly
  step ;;; another press stops it
end   ;;; end of to procedure

;;; end: arabesque