%% 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