object{ Ring_Sphere (Rmaj_H, Rmaj_V, Rmin_H, Rmin_V,
                     Number_of_Rings_horizontal,
                     Number_of_Rings_vertical)
        texture{ ... ... }
      } // end of object ------------------------

Deux boucles tant que d'anneaux, chaque rayon est calculé par une fonction cosinus :

//----------------------------------------------- macro Ring_Sphere(...) #macro Ring_Sphere (Rmaj_H, Rmaj_V, Rmin_H, Rmin_V, Number_of_Rings_horizontal, Number_of_Rings_vertical) #if (Rmin_H > 0) #declare RingsH1 = union{ #declare AngleD = 180/ Number_of_Rings_horizontal; #declare Nr = -90+AngleD; #declare EndNr = 90; #while (Nr < EndNr) #declare RingR = Rmaj_H*cos(radians(Nr)); #declare RingH = Rmaj_H*sin(radians(Nr)); torus{RingR,Rmin_H translate<0, RingH,0>} #declare Nr = Nr + AngleD; #end // --------------- end of loop #declare LastR= RingR; }//----------------- #end // of "#if (Rmin_H > 0)" #if (Rmin_V > 0) #declare RingsV1 = // vertical union{ #declare Nr = 0; #declare EndNr = Number_of_Rings_vertical #while (Nr < EndNr) torus{Rmaj_V-Rmin_V,Rmin_V rotate<90,0,0> rotate<0, Nr*360/EndNr,0>} #declare Nr = Nr + 1; #end // --------------- end of loop }//--------------------------------- #end // of "#if (Rmin_V > 0)" union{ #if (Rmin_H > 0) object{ RingsH1} #end #if (Rmin_V > 0) object{ RingsV1} #end sphere{<0, Rmaj_H,0>,Rmin_H} sphere{<0,-Rmaj_H,0>,Rmin_H} } #end //--------------------------------- end of macro Ring_Sphere(...)

Voici quelques variations de cette macro :
 

"Ring_Sphere(1.00, 1.02, 0.005, 0.005, 32, 46)"	"Ring_Sphere(1.03, 1.00, 0.015, 0.005, 30, 15)"