dim arena(100,100)
black=0
white=not(black)
for i = 1 to 100
  for j = 1 to 100
    arena(i,j)=white
  next
next
'north=1 east=2 south=3 west=4

nomainwin
graphicbox #1.g, 0, 0, 100, 100
open "Langton's Ant" for window as #1
#1 "trapclose Quit"
#1.g "down"

antX=50:antY=50
nsew=1    'ant initially points north

while (antX>0) and (antX<100) and (antY>0) and (antY<100)
    if arena(antX,antY) then
      nsew=nsew-1
      if nsew<1 then nsew=4
    else
      nsew=nsew+1
      if nsew>4 then nsew=1
    end if

    select case nsew
      case 1: antY=antY-1
      case 2: antX=antX+1
      case 3: antY=antY+1
      case 4: antX=antX-1
      end select

    arena(antX,antY)=not(arena(antX,antY))
    #1.g "color ";GetColor$(antX,antY)
    #1.g "set ";antX;" ";antY
wend

#1.g "flush"
wait

function GetColor$(x,y)
    if arena(x,y) then
        GetColor$="white"
    else
        GetColor$="black"
    end if
    end function

sub Quit handle$
    close #handle$
    end
    end sub