# Main Command: Go
# Zoom 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 gridd :m :n
  # return X Y screen position
  Make "X (:N*:CellSize) - 180 
  Make "Y (:M*:CellSize) - 180 
  Output List :X :Y
end

to drawgrid
  # draw M x N array of squares 
  For (List "N 5 1 Minus 1) [
    For (List "M 5 1 Minus 1) [
      SetPos Gridd (:M*:M)/5 (:N*:N)/5 Rect 8*:M 8*:N Left 90
      SetXY Minus 1*First Pos Last Pos Rect 8*:N 8*:M Left 90
      SetXY First Pos Minus 1*Last Pos Rect 8*:M 8*:N Left 90
      SetXY Minus 1*First Pos Last Pos Rect 8*:N 8*:M Left 90 ] ] 
end

to rect :width :height
  # shaded rectangle (width x height) drawn from centre (tp) and filled
  Back :Height/2 Right 90 Back :Width/2 PenDown
  SetPC Black Forward :Width Left 90 Forward :Height Left 90
  SetPC White Forward :Width Left 90 Forward :Height Left 90
  PenUp Forward :Width/2 Left 90 Forward :Height/2   # return to centre
  SetPC [153 0 204] Fill
end

to go
  New SetSC [51 204 102] SetPW 2
  Left 90     # change to 270 to fall in
  Make "CellSize 30 
  DrawGrid
end

to rect2 :width :height
  # shaded pebble shape drawn from centre (tp) and filled
  LocalMake "Diff Abs :Width-:Height
  If :Width > :Height [LocalMake "Rad :Height/2 LocalMake "Vert 0 LocalMake "Horiz :Diff]
                      [LocalMake "Rad :Width/2 LocalMake "Vert :Diff LocalMake "Horiz 0]
  PenUp Back :Height/2 Right 90 Back :Horiz/2 PenDown
  SetPC Black Forward :Horiz LeftArc 90 :Rad Forward :Vert LeftArc 45 :Rad
  SetPC White LeftArc 45 :Rad Forward :Horiz LeftArc 90 :Rad Forward :Vert LeftArc 45 :Rad
  SetPC Black LeftArc 45 :Rad
  PenUp Forward :Horiz/2 Left 90 Forward :Height/2   # return to centre
  SetPC [153 0 204] Fill
end

to leftarc :angle :radius
  # arc drawn relative to turtle position, angle & radius positive
  PenUp Right 90 Back :Radius Left :Angle
  Arc :Radius Heading Heading+:Angle
  Forward :Radius Left 90 PenDown
end