set pm3d depth lighting 
set object rect from sc 0,0 to sc 1,1 behind fc "#114400"
set palette defined (0 "#ffff99", 1 "#ffff99")
set samples 48
set isosamples 184
unset border
unset tics
unset colorbox
unset key
set xyplane 0
set view 150,170, 1.5, 
set term pngcairo size 360,360
set out "crescent.png"
set parametric
set urange [0:pi]
set vrange [-0.001:pi]
c = 3
set xrange [-c:c]
set yrange [-c:c]
set zrange [-c:c]
a=2
b=2
c=2
x(u,v) = (a + sin(b*u)*sin(b*v)) * sin(c*v)
y(u,v) = (a + sin(b*u)*sin(b*v)) * cos(c*v)
z(u,v) = cos(a*u)*sin(b*v) + 4*(v/pi) -2

splot x(u,v), y(u,v), z(u,v) w pm3d

!display "crescent.png"