set pm3d depth lighting primary 0.6
set object rect from sc 0,0 to sc 1,1 behind fc "#114400"
set palette defined (0 "#fffff0", 1 "#fffff0")
set samples 96
set isosamples 96
unset border
unset tics
unset colorbox
unset key
set xyplane 0
set view 75,30, 1.4,
set term pngcairo size 360,360
set out "handkerchief.png"
c = 0.2
set xrange[-c:c]
set yrange[-c:c]
set zrange[-c:c]

splot x**3/3 + x*y**2 + 2*(x**2-y**2) w pm3d
!display "handkerchief.png"