Présentation de lumiere_noir.jps

%% auteur : 

600 setwidth
400 setheight

-7 8 setxrange
-5 5 setyrange

/x_min -7 def
/x_max 7 def
/y_min -7 def
/y_max 7 def

/curvelinewidth 0 def

%% la source d'eclairage

/xp 3 def
/yp 3 def
/zp 7 def
/kp 8 def

/nx 150 def
/ny 150 def

%% f (x, y) = sin (x^2 + y^2)

/f {
%%   2 copy 

%%   0 eq

%%    {

%% 	 0 eq

%% 	    {1}

%% 	    {dup mul exch dup mul add dup Sin exch div}

%% 	 ifelse

%%    }

%%    {

%% 	 pop

%% 	 dup mul exch dup mul add dup Sin exch div

%%    }

%%   ifelse

  dup mul exch dup mul add dup Sin exch .001 max div 
} def

/f {
   0 0 distance sqrt
} def

/f {Sin exch Sin add} def

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

%% syntaxe : x y z XYZtoXY --> X Y

/XYZtoXY {
3 dict begin
   /z exch def
   /y exch def
   /x exch def
   vect_I x mulv
   vect_J y mulv addv
   vect_K z mulv addv
end
} def

%% syntaxe : x y (f) diffx 

/diffx {
3 dict begin
   /la_fonction exch cvx def
   /y exch def
   /x exch def
   x .01 add y la_fonction
   x .01 sub y la_fonction sub
   .02 div
end
} def

%% syntaxe : x y (f) diffy

/diffy {
3 dict begin
   /la_fonction exch cvx def
   /y exch def
   /x exch def
   x y .01 add la_fonction
   x y .01 sub la_fonction sub
   .02 div
end
} def

%% syntaxe : x y z (f) facteur

/facteur {
4 dict begin
   /fonction exch cvx def
   /z exch def
   /y exch def
   /x exch def
   /dfx x y (fonction) diffx def
   /dfy x y (fonction) diffy def
   /ca 
      zp z sub
      yp y sub dfy mul sub
      xp x sub dfx mul sub
   def
   /cb
      dfx dup mul
      dfy dup mul add
      1 add
      sqrt
   def
   /cc
      z zp sub dup mul
      y yp sub dup mul add
      x xp sub dup mul add
      sqrt
   def
   kp ca mul 
   cc dup dup mul mul cb mul div
end
} def

/dx 
   x_max x_min sub nx div 
def
/dy
   y_max y_min sub ny div 
def

/fillstyle {
%%    [ 1 .65 0 ] %% orange

%% %   [ 1 0 0 0 ] %% cyan

%%    {kp coeff_couleur abs mul mul} apply

%%    aload pop 

%% %   setcmykcolor 

%%    setrgbcolor

%% %   setgray 

   fill
} def

/i 0 def
nx 1 sub {
   /xt x_min i dx mul add def
   /xt+1 xt dx add def
   /j 0 def
   ny 1 sub {
      /yt y_min j dy mul add def
      /yt+1 yt dy add def
      /coeff_couleur xt yt 2 copy f (f) facteur def
      
      xt yt 2 copy f XYZtoXY /A0 defpoint
      xt yt+1 2 copy f XYZtoXY /A1 defpoint
      xt+1 yt+1 2 copy f XYZtoXY /A2 defpoint
      xt+1 yt 2 copy f XYZtoXY /A3 defpoint
      
      gsave
%   [ 1 .65 0 ] %% orange

   [ 1 0 1 1 ] %% cyan

   {kp coeff_couleur abs mul mul} apply
   aload pop 
   setcmykcolor 
%   setrgbcolor

   	 [A0 A1 A2 A3] polygone*
      grestore
      /j j 1 add store
   } repeat
   /i i 1 add store
} repeat