%!PS-Adobe-2.0
%%BoundingBox: 0 0 300 300

% specify the width and height for good placement
/w 300 def
/h 300 def
/eye [ 1.3 -1.75 ] def

(epsetup.inc) run

% v A -> v rotated by A
/rotate-vector { 1 dict begin
  /A exch def
  /v exch def
  /c A cos def 
  /s A sin def
  [ v 0 get c mul v 1 get s mul sub
  v 0 get s mul v 1 get c mul add ]
end } def

/color [ [ 1 0 0 ] [ 0 0 1 ] ] def

% faces[0] points towards positive z-axis
/faces[
  [[ 0.25 0.25 ] [ 1.25 0.25 ] [ 1.25 1.25 ] [ 0.25 1.25 ]]
  [[ -0.25 -0.25 ] [ -1.25 -0.25 ] [ -1.25 -1.25 ] [ -0.25 -1.25 ]]
] def

% separated by x+y=0: perpendicular to [1 1]
% spanned by [ 1 -1]
/F [ 1 -1 ] def
/N [ 1 1 ] def

/A 0 def
/dA 10 def

{ 

page-begin
  gsave
  A rotate
  % draw the separating line
    N 0 get eye 0 get mul 
    N 1 get eye 1 get mul 
    add 
  0 ge {
    /dx 3 def /dy 3 def
  }{
    /dx -3 def /dy -3 def
  } ifelse
  gsave
  newpath
  F 0 get 3 mul F 1 get 3 mul moveto
  F 0 get -3 mul F 1 get -3 mul lineto
  dx dy lineto
  F 0 get 3 mul F 1 get 3 mul lineto
  closepath
  gsave
  0.9 setgray
  fill
  grestore
  stroke
  grestore

  newpath
  0 1 1 { /i exch def
    /f faces i get def
    f 3 get aload pop moveto
    f { aload pop lineto } forall
    closepath
    gsave
    color i get aload pop setrgbcolor
    fill
    grestore
    stroke
  } for

  grestore

  gsave
  currentlinewidth 2 mul setlinewidth
  newpath
  eye aload pop 0.075 0 360 arc 
  stroke
  grestore
page-end 
  /A A dA add def
  /N N dA rotate-vector def
} loop