28.4527 setxunit %% 10 mm
%60 setxunit
-0.1 5 setxrange
-0.1 2 setyrange

%[1 1 .5 .5 .1 .1] {orange} Quadrillage

%tracerepere marks

/A {0 0.8} def
/x1 2 def
/x2 0.2 def
/x {x1 x2} def
/xx {-x1 -x2} def
/y1 1 def
/y2 1 def
/y {y1 y2} def
/yy {-y1 -y2} def

/O {A x addv} def
/B {1 0} def
/C {O x addv} def
/D {O y addv} def
A D (->) line
A O (->) line
O D (->) line
A B (->) line

0.7 setlinewidth
[A C] ligne
[B D] ligne
[A B C D] polygone