aUCBLogo Demos and Tests / ant

be ant
   norefresh
   ht
   cs
   t=timefine
   start=100
   finish=200
   for [i start finish]
   [   for [j start finish]
      [   make (word "field :i :j) 0
      ]
   ]
   n=20000
   antx=(start+finish)/2
   anty=(start+finish)/2
   jump=3
   stepcount=0
   framedelay=20
   append=false
   for [a 1 n]
   [   ifelse (or antx<start anty<start antx>finish anty>finish)
      [   print [error: ant went to far]
         (pr timefine-t "sec)
         stop
      ]
      [move]
      if (mod a 20)==0
      [   updateGraph
      ]
   ]
   (pr timefine-t "sec)
   refresh

   be move
      ifelse (thing (word "field :antx :anty)) ==0
      [   squareblack :jump rt 90 fd :jump
         make (word "field :antx :anty) 1
      ][   squarewhite :jump lt 90 fd :jump
         make (word "field :antx :anty) 0
      ]
      ifelse or (heading==90) (heading==270)
      [   ifelse (heading==90)
         [   antx=antx+1
         ][   antx=antx-1
         ]
      ][   ifelse (heading==0)
         [   anty=anty+1
         ][   anty=anty-1
         ]
      ]
   end

   be squareblack :size
      setpc 0
      pd
      fd (:size-1)/2
      rt 90
      repeat :size-1
      [   fd (:size-1)/2
         bk :size-1
         fd (:size-1)/2
         rt 90 fd 1 lt 90
      ]
      fd (:size-1)/2 bk :size-1 fd (:size-1)/2
      lt 90 fd (:size-1)/2
      penup
      stepcount=stepcount+1
   ;   if :stepcount == :framedelay
   ;   [   (gifsave "ant.gif 0 :append 0)
   ;      stepcount=0
   ;      append=true
   ;   ]
   end

   be squarewhite :size
      setpc 7
      pd
      fd (:size-1)/2
      rt 90
      repeat :size-1
      [   fd (:size-1)/2
         bk :size-1
         fd (:size-1)/2
         rt 90 fd 1 lt 90
      ]
      fd (:size-1)/2 bk :size-1 fd (:size-1)/2
      lt 90 fd (:size-1)/2
      penup
      stepcount=stepcount+1
   ;   if :stepcount == :framedelay
   ;   [   (gifsave "ant.gif 0 :append 0)
   ;      stepcount=0
   ;      append=true
   ;   ]
   end
end