# Original example:
# http://gnuplot.sourceforge.net/demo/hidden2.html

using Gnuplot

@gsp "set multiplot title 'Interlocking Tori'"
U = LinRange(-pi, pi, 100); # 50
V = LinRange(-pi, pi, 20);

@gsp :- "unset key"
@gsp :- "unset xtics"
@gsp :- "unset ytics"
@gsp :- "unset ztics"
@gsp :- "set border 0"
@gsp :- "set view 60, 30, 1.5, 0.9"
@gsp :- "unset colorbox"
@gsp :- "set colorbox vertical user origin 0.9, 0.15 size 0.02, 0.50"
@gsp :- "set format cb '%.1f'"

for loop in 1:2
    if loop == 1
        @gsp :- 1 title="PM3D surface\\nno depth sorting"
        @gsp :- "set origin -0.02,0.0"
        @gsp :- "set size 0.55, 0.9"
        @gsp :- "set pm3d scansforward" :-  # scansbackward
    else
        @gsp :- 2 title="PM3D surface\\ndepth sorting"
        @gsp :- "set origin 0.40,0.0"
        @gsp :- "set size 0.55, 0.9"
        @gsp :- "set pm3d depthorder"
    end
    x = [cos(u) + .5 * cos(u) * cos(v)      for u in U, v in V]
    y = [sin(u) + .5 * sin(u) * cos(v)      for u in U, v in V]
    z = [.5 * sin(v)                        for u in U, v in V]
    @gsp :- x' y' z' "w pm3d"

    x = [1 + cos(u) + .5 * cos(u) * cos(v)  for u in U, v in V]
    y = [.5 * sin(v)                        for u in U, v in V]
    z = [sin(u) + .5 * sin(u) * cos(v)      for u in U, v in V]
    @gsp :- x' y' z' "w pm3d"
end