# Drawing Cross Sections of (Contours over) Torus

I have this simple torus

\begin{figure}
\begin{center}
\begin{pspicture}(-6,-4)(6,4)
\psset{viewpoint=30 10 25 rtp2xyz,Decran=30,lightsrc=viewpoint}
\psSolid[object=tore,r1=2.5,r0=1.0,ngrid=36 72,fillcolor=blue!30,grid=false]%
\end{pspicture}
\end {center}
\end{figure}


as depicted,

It is parallel to x-y plane; aligned to z-axis at its centre. (Light source could be not in its best point, though.)

I need to draw over it its cross sections in contour forms parallel to yz - plane (or xz - plane); that is, contours in direction of x. I'll be obliged for any hint.

Most inspiring camera point is where it can show contours at the very inner points before separation into two lobes.

Contours are famous spiric sections (r2 - a2 + c2 + x2 + y2)2 = 4r2(x2 + c2), where, c is the contours parameter, and the torus is formed from a circle of radius a whose centre is rotated along a circle of radius r.