Geometriesyr16 - Exemple 6

 input geometriesyr16;
 typerepre:="persp";
 
 

 figureespace(-5u,-5u,5u,5u);
 Initialisation(10,0,10,35);
 trace cercles((0,0,0),(0,0,2),(0,0,0),(0,1,0),(0,0,1));
 path CL;
 color M,M';
 color Cent;
 M=(0,2*cosd(-130),2*sind(-130));
 Cent=ProjectionsurPlan(M,(0,0,0),(0,2*cosd(120),2*sind(120)),(1,0,0));
 M'=(-1,greenpart(Cent),bluepart(Cent));
 path Sect;
 Sect=cercles(Cent,M,Cent,M,M');
 remplis Sect withcolor 1.1*gris;
 trace subpath(0,length Sect/2) of Sect dashed evenly;
 trace subpath(length Sect/2,length Sect) of Sect;
 CL=cercles((0,0,0),(0,2,0),(0,0,0),(0,1,0),(1,0,0));
 trace subpath(0,length CL/2) of CL;
 trace subpath(length CL/2,length CL) of CL dashed evenly;
 trace polygone(Cent,M,(0,0,0)) dashed evenly;
 trace codeperp((0,0,0),Cent,M,5);
 marque_p:="plein";
 pointe(M,(0,0,0),Cent);
 marque_p:="non";
 label.top(btex $O$ etex,Projette((0,0,0)));
 label.bot(btex $I$ etex,Projette(Cent));
 label.llft(btex $M$ etex,Projette(M));
 finespace;
 
 

 figureespace(-5u,-5u,5u,5u);
 Initialisation(10,0,10,35);
 color M,M',Cent;
 path CL,CF,Sect,plansec;
 CL=cercles((0,0,0),(0,2,0),(0,0,0),(0,1,0),(1,0,0));
 CF=cercles((0,0,0),(0,0,2),(0,0,0),(0,1,0),(0,0,1));
 M=(0,2*cosd(-130),2*sind(-130));
 Cent=ProjectionsurPlan(M,(0,0,0),(0,2*cosd(120),2*sind(120)),(1,0,0));
 M'=(-1,greenpart(Cent),bluepart(Cent));
 Sect=cercles(Cent,M,Cent,M,M');
 plansec=polygone(M'+2*(M'-Cent)+1.5*(M-Cent),M+3*(Cent-M')+0.5*(M-Cent),
   Cent+1.5*(Cent-M)+3*(Cent-M'),M'+2*(M'-Cent)+1.5*(Cent-M));
 %partie supérieure
 trace plansec cutafter CF;
 trace segment(M'+2*(M'-Cent)+1.5*(M-Cent),M'+2*(M'-Cent)+1.5*(Cent-M)) cutafter reverse(CF);
 trace plansec cutbefore CF dashed evenly;
 trace CF cutbefore demidroite(Cent,symetrie(M,Cent)) cutafter segment(M,M);
 remplis Sect withcolor 1.1*gris;
 trace subpath(0,length Sect/2) of Sect dashed evenly;
 trace subpath(length Sect/2,length Sect) of Sect;
 trace polygone(Cent,M,(0,0,0)) dashed evenly;
 trace codeperp((0,0,0),Cent,M,5);
 marque_p:="plein";
 pointe(M,(0,0,0),Cent,M');
 marque_p:="non";
 label.top(btex $O$ etex,Projette((0,0,0)));
 label.bot(btex $I$ etex,Projette(Cent));
 label.llft(btex $M$ etex,Projette(M));
 %partie inférieure
 picture sectiondecalee;
 sectiondecalee=image(
   trace CF cutafter demidroite(Cent,symetrie(M,Cent));
   trace CF cutbefore segment(M,M);
   trace Sect;
   trace hachurage(Sect,60,0.2,0);
   );
 trace sectiondecalee shifted(3*(Projette(Cent)-Projette((0,0,0))));
 drawarrow segment(M+2*Cent,Cent+3*Cent);
 label.lft(btex Section etex,Projette(M+2*Cent));
 finespace;
 
 end