-1 9 setxrange
-2 6 setyrange

/x 3 def

/dy .5 def
/dz dy .4 add def

/A {0 0} def
/B {8 0} def
/Q {8 8 x sub} def
/M {x 0} def
/P {0 x} def
/N {x x} def
/R {x 8 x sub} def

/N1 {N 0 dy addv} def
/P1 {P 0 dy addv} def

/A1 {A 0 dz subv} def
/B1 {B 0 dz subv} def

N1 P1 (<->) line
A1 B1 (<->) line

gsave
   pointilles
   [P P1] ligne
   [A A1] ligne
   [B B1] ligne
grestore

medium setlinewidth
[A M N P] polygone
[M R Q B] polygone

setTimes
   (8) A1 B1 milieu dtext
setTimesItalic
   (P) P ltext
   (A) A dltext
   (B) B drtext
   (M) M drtext
   (N) N rtext
   (R) R ltext
   (Q) Q rtext
   (x) N1 P1 milieu utext