#!/usr/local/bin/gnuplot -persist
# set terminal pngcairo  transparent enhanced font "arial,10" fontscale 1.0 size 600, 400 
# set output 'surface2.8.png'
set dummy u, v
set key bmargin center horizontal Right noreverse enhanced autotitle nobox
set parametric
set view 50, 30, 1, 1
set isosamples 40, 20
set hidden3d back offset 1 trianglepattern 3 undefined 1 altdiagonal bentover
set style data lines
set xyplane relative 0
set title "Parametric Shell (automatic z range)" 
set urange [ 0.00000 : 6.28319 ] noreverse nowriteback
set vrange [ 0.00000 : 6.28319 ] noreverse nowriteback
set xrange [ * : * ] noreverse writeback
set x2range [ * : * ] noreverse writeback
set yrange [ * : * ] noreverse writeback
set y2range [ * : * ] noreverse writeback
set zrange [ * : * ] noreverse writeback
set cbrange [ * : * ] noreverse writeback
set rrange [ * : * ] noreverse writeback
set colorbox vertical origin screen 0.9, 0.2 size screen 0.05, 0.6 front  noinvert bdefault
NO_ANIMATION = 1
splot cos(u)*u*(1+cos(v)/2),sin(v)*u/2,sin(u)*u*(1+cos(v)/2)