% sort out scaling and translating
36 36 translate
/sf 540 640 div def
sf sf scale

% width/height ratio
/whr 10 7.5 div def

% center things vertically
0 whr 640 mul 576 sub 2 div translate

% translate off to the left one tile and clip
64 neg 0 translate
64 0 640 576 rectclip

% draw the up moving diagnals
/sx 0 def
/sy 288 def
/ex 384 def
/ey 576 def

1 1 13 {
  sx sy moveto
  ex ey lineto
  stroke
  /sx sx 32 add def
  /ex ex 32 add def
  /sy sy 24 sub def
  /ey ey 24 sub def
} for

% draw the down moving diagnals
/sx 0 def
/sy 288 def
/ex 384 def
/ey 0 def

1 1 13 {
  sx sy moveto
  ex ey lineto
  stroke
  /sx sx 32 add def
  /ex ex 32 add def
  /sy sy 24 add def
  /ey ey 24 add def
} for

% box the whole thing in
64 0 640 576 rectstroke

showpage