set pm3d explicit
set palette  rgb 7,0,0
unset key
unset colorbox
set hidden3d
set parametric
set ticslevel 0
set size square
set view 75,5,1.5,1
set isosamples 25,18
set urange[0:pi] 
set vrange[-pi:pi]
set term png transparent xffffff 
set out "heart.png"
set multiplot
splot sin(u)*cos(v),sin(u)*sin(v),cos(u)+sin(u) w pm3d
splot sin(u)*cos(v),sin(u)*sin(v),cos(u)+sin(u) lt 6
unset multiplot
!convert -geometry 40% -colors 256 heart.png heart_s.png
!display heart_s.png