# Main Command: go
# Knight's Tour 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 init
  # global values
  GlobalMake "Order 4
  GlobalMake "CellSize (First ScreenSize) /:Order
  GlobalMake "OffSet ((First ScreenSize) -:CellSize) /2 
end

to screenpos :cellx :celly :cellz
  # return X Y Z screen position
  # use global values of CellSize and Offset
  Make "PosX (:CellX*:CellSize) -:OffSet
  Make "PosY (:CellY*:CellSize) -:OffSet
  Make "PosZ (:CellZ*:CellSize) -:OffSet 
  Output (List :PosX :PosY :PosZ)
end

to drawgrid
  # draw X by Y by Z array of cubes
  For (List "CellX 0 :Order-1) [
    For (List "CellY 0 :Order-1) [
      For (List "CellZ 0 :Order-1) [ 
        SetPos ScreenPos :CellX :CellY :CellZ
        Cube :CellSize/4 ] ] ]
end

to cube :side
  # draw a skeleton cube from center, tp
Right 45 Back :Side/1.414 Left 45 Up 90 Back :Side/2 PenDown
  Repeat 2 [Repeat 2 [
      LineStart Forward :Side Down 90 Forward :Side Down 90 Forward :Side LineEnd
      Back :Side Right 90] Left 180]
      PenUp Forward :Side/2 Down 90 Right 45 Forward :Side/1.414 Left 45
end

to tour
  # knight's 64 position tour, xyz
  Make "Tour [003 022 030 132 120 101 113 211 203 222 230 332 320 301 313 321 300 312 333 231 210 202 223 121 100 112 133 031 010 002 023 103 122 130 111 213 232 220 201 303 322 330 311 323 331 310 302 200 212 233 221 123 131 110 102 000 012 033 021 013 001 020 032 011]
  SetPW 4 SetPC Red PenUp
  SetPos ScreenPos 0 1 1 PenDown 
  LineStart Repeat 64 [
    Make "PosXYZ Item RepCount :Tour
    Make "Hor Item 1 :PosXYZ
    Make "Ver Item 2 :PosXYZ
    Make "Dep Item 3 :PosXYZ
    SetPos ScreenPos :Hor :Ver :Dep] LineEnd
end

to go
  New Perspective CS PenUp
  HideTurtle SetSC Black SetPC Green
  Init DrawGrid Tour Wait 30
  Message [View3D?] View3D
end