%!PS-Adobe-2.0
%%BoundingBox: 0 0 80 80

/w 80 def
/h 80 def

(ps3d.inc) run
(cube.inc) run
(epsetup.inc) run

% ------------------------------------------------

[0 0 3 1] set-eye
0 0 -2 translate3d

page-begin

gsave3d

[1 1 1] A rotate3d
-0.5 -0.5 -0.5 translate3d
/E get-virtual-eye def
/L get-virtual-light def
% L = light in current coordinates

cube {
  % [ [P[0] P[1] ... P[n-1]] n ]
  dup 
  1 get /n exch def
  0 get /f exch def
  % n = normal function
  /ell f length def
    n 
    E 
    dot-product
  0 ge 
  {
    newpath
    f ell 1 sub get aload pop moveto3d
    f {
      aload pop lineto3d
    } forall
    gsave
      n L 
    dot-product
    [0.30 0.30 0.80 1] 
    shade 0 0 setrgbcolor
    fill
    grestore
    stroke
  } if
} forall

grestore3d

page-end