-2 2 setxrange
-1.5 1.5 setyrange
50 setxunit

8 -8 6 SetCamPos
0 0 0 SetCamView
qplanxy
-10 10 setxrange3d
-3 3 setyrange3d

/f {
1 dict begin
  /t exch def
#rpn# Cos (3*t)
#rpn# Sin (3*t)
#rpn# t/8
end
} def

0 .95 1.3 [4 18] newcylindre
dup (.5 setfillopacity jaune) solidputcolors

0 pi 3 mul {f} [300] newcourbe
dup (bleu) solidputcolors

solidfuz
gris
drawsolid**

noir
#tex# $$f (t) = \big(\cos 3t, \sin 3t,t/8\big)$$
0 ymin [1.6 dup] uctexlabel