# Main Command: Go
# Langtons Ant by Guy Walker
# www.logoarts.co.uk

to new
# set default screen, pen and turtle 
ResetAll SetScreenSize [400 400] HideTurtle 
SetSC Black SetPC Green SetPS 1 PenUp 
end

to nextstep
Make "Col Item 2 FindColor Pos
SetPC AngCol Dot Pos
If :Col = 0 [Left 90 Forward 6 Stop]
If :Col = 255 [Right 90 Forward 6]
end

to angcol
Make "Num Item 1 FindColor Pos
Make "Red :Num + 0.2 * (255-:Num)
Make "Green 255 - Item 2 FindColor Pos
Output ( List :Red :Green 0 )   # replace :Red with 0 for b&w image
end

to go
New SetPS 0 SetPW 4
Repeat 10700 [NextStep]
end