set pm3d depth lighting primary 0.5
set object rect from sc 0,0 to sc 1,1 behind fc "#114400"
set palette defined (0 "#6666ff", 1 "#6666ff")
set samples 128
set isosamples 128
unset border
unset tics
unset colorbox
unset key
set xyplane 0
set view 60,80, 1.5,0.8 
set term pngcairo size 360,360
set out "func003.png"

f(x,y) = -x**3+3*x*y-y**3 
c = 3
set xrange [-c:c]
set yrange [-c:c]
splot f(x,y) < -3 ? -3: f(x,y) > 1 ? 1: f(x,y) w pm3d

!display "func003.png"