sphere_x := proc(r,u,v)
begin
  r*sin(u)*sin(v):
end_proc:

sphere_y := proc(r,u,v)
begin
  r*sin(u)*cos(v):
end_proc:

sphere_z := proc(r,u,v)
begin
  r*cos(u):
end_proc:

plot3d(Axes = None,
       Title = "Three Spheres",
       TitlePosition = Below,
       CameraPoint = [-6,1.2,2.8],
       [Mode=Surface,
       [hold(sphere_x(1,u,v)),
        hold(sphere_y(1,u,v)),
        hold(sphere_z(1,u,v))],
        u = [PI/2,PI], v=[0,2*PI],
        Grid = [20,20], Smoothness = [0,1],
        Style = [ColorPatches, AndMesh]],
       [Mode=Surface,
       [hold(sphere_x(2/3,u,v)),
        hold(sphere_y(2/3,u,v)),
        hold(sphere_z(2/3,u,v))],
        u = [0,PI], v=[0,PI], Grid = [15, 15],
        Style = [Transparent, AndMesh]],
       [Mode=Surface,
       [hold(sphere_x(1/3,u,v)),
        hold(sphere_y(1/3,u,v)),
        hold(sphere_z(1/3,u,v))],
        u = [0,PI], v=[0,2*PI], Grid = [15, 15],
        Style = [ColorPatches, AndMesh]]);
