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"