x1(u,v)=cos(u)+.5*cos(u)*cos(v)
y1(u,v)=sin(u)+.5*sin(u)*cos(v)
z1(u,v)=.5*sin(v)
x2(u,v)=1+cos(u)+.5*cos(u)*cos(v)
y2(u,v)=.5*sin(v)
z2(u,v)=sin(u)+.5*sin(u)*cos(v)
#
set style line 100 lw 0.1 lc rgb "navy"
set pm3d depthorder hidden3d ls 100
set palette defined (0 "dark-green", 1 "white")
set parametric
set urange [0:2*pi]
set vrange [-pi:pi]
set samples 48
set isosamples 48,24
set view 60,15,1.2
unset key
set ticslevel 0
splot x1(u,v), y1(u,v), z1(u,v) w pm3d,\
      x2(u,v), y2(u,v), z2(u,v) w pm3d 
pause 3
set term pngcairo size 480,480 
set output "tori.png"
replot