using Gnuplot
empty!(Gnuplot.options.init)
push!( Gnuplot.options.init, linetypes(:Set1_5, lw=1.5, ps=1.5))
function saveas(file; sx=550, sy=350, fs=0.8, term="svg")
    Gnuplot.save(term="$(term) size $(sx),$(sy) fontscale $(fs)", "$(file).svg")
end;

Torus: wireframe

U  = LinRange(-π,π, 50)
V = LinRange(-π,π, 30)
r = 0.5
x = [1 + cos(u) + r * cos(u) * cos(v)  for u in U, v in V]
y = [r * sin(v)                        for u in U, v in V]
z = [sin(u) + r * sin(u) * cos(v)      for u in U, v in V]
@gsp "set pm3d depthorder"
@gsp :- "set style fill transparent solid 0.5"
@gsp :- "set pm3d lighting primary 0.05 specular 0.2"
@gsp :- x y z "w l palette notit" palette(:dense) "set view 108,2"
@gsp :- "unset border" "set xyplane 0"
@gsp :- "unset tics"
@gsp :- "unset colorbox"
saveas("wires003");