-2 2 setxrange
-2 1 setyrange
100 setxunit

0 20 -10 SetCamPos
-1 0 0 SetCamUp
0 0 0 SetCamView

-10 10 setxrange3d
-10 10 setyrange3d

5 5 5 setlightsrc
1.5 setlightintensity

2 setlinejoin 

/twister {
3 dict begin
   /v exch def
   /u exch def
#rpn# Cos(u)*(4*sqrt(1-v^2)*Sin(abs(u))^(abs(u)))
v
#rpn# Sin(u)*(4*sqrt(1-v^2)*Sin(abs(u))^abs(u))
end
} def

gris

.1 setlinewidth

%% d apres un code original de Juergen Gil
%% http://melusine.eu.org/lab/bpst/pst-solides3d/surfaces/ex_4.pst

pi neg pi -1  1 [50 dup] {twister} newsurfaceparametree
dup videsolid
dup (rouge) (rouge)  inoutputcolors
drawsolid**