600 setwidth
400 setheight

-7 8 setxrange
-5 5 setyrange

%% la source d'eclairage
/src {3 3 7} def
/kp 8 def

/f {Sin exch Sin add} def

/vect_I {-.7 -.5} def
/vect_J {1 0} def
/vect_K {0 1} def

%% syntaxe : nx ny (f) src_pt [color] kp x_min x_max y_min y_max surfz
150 150 (f) src [ 1 0 1 1 ] kp -7 7 2 copy surfz