[pstricks] Re : plansepare with a surface

[Herbert Voss]

Am 26.02.2011 16:59, schrieb Markus Krebs:

> The plane cutting the paraboloid shoud be the xz-plane: y = 0
> 
> Restricting the values for y, here y < 0 should do the job.
> 
>    h=2, %% hauteur 0<z<2
> 
> -4 < y < 0
> 
> Is this possible?

you can use the parametric form of the paraboloid

\documentclass{article}
\usepackage{pst-solides3d}
\begin{document}

\psset{lightsrc=viewpoint,viewpoint=50 60 25 rtp2xyz,Decran=50}
\begin{pspicture}(-5,-3)(6,6)
\psSolid[object=grille,base=-4 4 -4 4](0,0,0)
\defFunction[algebraic]{paraboloid}(u,v)
   {4*sqrt(u/4)*cos(v)}
   {4*sqrt(u/4)*sin(v)}
   {-u+4}
\psSolid[object=surfaceparametree,base=0 4 0 pi neg,
  ngrid=20 20,incolor=red!40,fillcolor=yellow!50,
  intersectionplan={[0 1 0 0]},
  intersectioncolor=(bleu),
  intersectionlinewidth=2,
  intersectiontype=1,
  function=paraboloid]
\gridIIID[Zmin=0,Zmax=4,spotX=r](-4,4)(-4,4)
\end{pspicture}

\end{document}

Herbert