%% auteur : 






%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% PhS
%%

%% échelle et étendue de l'image
60 setxunit
-3.5 3.5  setxrange
-3 4 setyrange


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  DANGER !! Il ne faut pas utiliser de variables
%%  DANGER !! qui commence par les lettres :
%%  DANGER !! xmin, xmax, ymin et ymax...
%%  DANGER !! Utiliser x_min, y_min...
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% procédures
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%% procedure sphere_parallele
/parallele_de_sphere { %% R (rayon) phi (lattitude deg) alpha (inclinaison deg)
6 dict begin
   /alpha exch def
   /phi exch def
   /R exch def
   /Xdet {
   1 dict begin
       /t exch def
       R phi sin mul t cos mul
   end
   } def
   /Ydet {
   1 dict begin
       /t exch def
       phi cos alpha cos mul phi sin alpha sin mul t sin mul sub R mul
   end
   } def
   90 phi eq
     {/phi phi 1.001 mul def}
   if
   1 alpha tan phi tan div lt
     {/tmax -90 def}
     { alpha tan phi tan div -1 lt
       {/tmax 90 def}
       {/tmax alpha tan phi tan div neg arcsin def}
     ifelse}
   ifelse
   gsave
   tmax dup neg 180 add settrange
   {Xdet} {Ydet} courbeparam
   grestore
end
   } def



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% définitions des couleurs
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

/coul1 {120 255 div 70 255 div 9 255 div setrgbcolor} def



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% tracés
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%% tracé des axes et du point Origine
1 setlinewidth
15 setfontsize
noir
continu
traceaxes
marks
tracerepere



rouge
0 0 3 cercle

coul1
3 5 30 parallele_de_sphere
3 15 30 parallele_de_sphere
3 25 30 parallele_de_sphere

3 30 30 parallele_de_sphere
3 40 30 parallele_de_sphere
3 50 30 parallele_de_sphere
3 60 30 parallele_de_sphere
3 70 30 parallele_de_sphere
3 80 30 parallele_de_sphere
3 90 30 parallele_de_sphere
3 100 30 parallele_de_sphere
3 110 30 parallele_de_sphere
3 140 30 parallele_de_sphere

3 155 30 parallele_de_sphere
3 165 30 parallele_de_sphere
3 175 30 parallele_de_sphere