let M=point3d(x,y,z)
let N=point3d(3,4,5,false)
let v = vecteur3d(u,v,w)
let V = v.representant(M)
let a=arete3d(M,N)
let d = droite3d(M,v)
let c = demicercle3d(O,v,r,'caché','red')
let C = cercle3d(O,v,r,visibilite,'blue')
let P = polygone3d([A,B,C,D],'orange') ou P=polygone3d(A,B,C,D)
let S = sphere3d(O,r,3,5,'green')
let cone=cone3d(O,s,v,r)
let pave=pave3d(A,B,C,D,'black')
let barette=barre3d(x,y,z,2,5,'black')
let plaquette=plaque3d(x,y,z,2,4,5)
let bloc=paveLPH3d(x,y,z,1,10,5,4)