.PS
# Eye.m4
# https://getpocket.com/explore/item/pillars-of-fire-truly-adventurous?utm_source=pocket-newtab
gen_init

define(`eye',`[ u = `$1'; v = 0.47*u; w = 0.25*u
#                                for pdf, linethick in shade must be environment
  lth = linethick; linethick = 0
  shade(1,
    arc outlined "red" from (u/2,0) to (-u/2,0) with .c at (0,-u/3)
    arc to (u/2,0) with .c at (0,u/3) )
  linethick = lth
  circle diam v fill_(0.25) at (0,0)
  circle diam w fill_(0) at (0,0)
  circle thick 0 diam last circle.diam/2 fill_(1) at last circle.nw
  circle diam last circle.diam-lthick at last circle outlined graystring(0.9)
  ] ')

  skale = 2/3
  Bx: box wid 11*skale ht 8.5*skale fill_(0) at (0,0)
  ane = atan2(Bx.ht,Bx.wid)*rtod_
  d[5] = 0.92*Bx.ht
  d[4] = 0.78*Bx.ht
  d[3] = 0.62*Bx.ht
  d[2] = 0.40*Bx.ht
  d[1] = 0.25*Bx.ht
  da = 1
  dax = 360/64
  C[0]: Bx.se; C[1]: Bx.nw
  for a=-int(ane/dax)*dax to 180-ane by dax do {
    T1: (Rect_(1,a+da)); T1: intersect_(Bx.ne,C[(a>ane)],Bx,T1)
    T2: (Rect_(1,a));    T2: intersect_(Bx.ne,C[(a>ane)],Bx,T2)
    line outlined "white" shaded "white" from Bx to T1 then to T2 then to Bx
    line outlined "white" shaded "white" from Bx to T1*(-1) \
      then to T2*(-1) then to Bx
    }
  for i=5 to 2 by -1 do {
    C[i]: circle diam d[i] fill_(0) at Bx
    for a=0 to 359 by dax do {
      T1: (Rect_(d[i]/2,a))
      T2: (Rect_(d[i]/2,a-da*2))
      lth = linethick; linethick = 0
      shade(1,
        arc cw from T1 to T2 with .c at Bx
        spline 0.55 thick 0 to 0.8 between Bx and T2 \
          then to (Rect_(d[i]/4,a+30))
        arc cw to (Rect_(d[i]/4,a+32)) with .c at Bx
        spline 0.55 thick 0 to 0.8 between Bx and T1 then to T1 )
      linethick = lth
      }
    }
  C[1]: circle thick 2 diam d[1] at Bx fill_(0.1)
  eye(d[1]-4bp__) at (0,0)
  for a=0 to 359 by dax do {
    T1: (Rect_(d[1]/2-1bp__,a))
    T2: (Rect_(d[1]/2-1bp__,a+dax/2))
    line thick 0 from T1 to T2 then to 0.5 between Bx and T2 \
      then to 0.5 between Bx and T1 then to T1 shaded "white" #outlined "white"
    }

.PE