import solids;
settings.render=0; 
settings.prc=false; // on se restreint à une vue 2d

size(6cm,0);

currentprojection=orthographic(10,5,2);
dotfactor=3.5;

real a=3;
triple pO=(0,0,0);
revolution b=sphere(pO,a);

skeleton s;
b.transverse(s,reltime(b.g,0.5),P=currentprojection);
draw(s.transverse.back,red+linetype("8 8",8));
draw(s.transverse.front,blue);
draw(b.silhouette(),black);
dot(pO);