Schéma en 3D

\documentclass[tikz]{standalone}
\usetikzlibrary{3d}
\usepackage{tikz-3dplot}   
\tdplotsetmaincoords{15}{10}
\begin{document}
\begin{tikzpicture}[
    samples=200,
    scale = 7,
    tdplot_main_coords,
    declare function={ f(\x,\y) = \x - .6 * \x*\x - 1.3 * \y*\y ;},
  ]
  \foreach \y in {0,.2,...,1.8}
  {
    \begin{scope}[canvas is xz plane at y=\y]
      \draw[domain=-1:3, smooth, variable=\x,red!85!black,ultra thick] plot ({\x}, {f(\x,\y)});
    \end{scope}
  }
  \foreach \x in {-1,0,.1,.2,1.4,2,2.1,...,3.1}
  {
    \begin{scope}[canvas is yz plane at x=\x]
      \draw[domain=-0:1.8, smooth, variable=\y,blue,ultra thick] plot ({\y}, {f(\x,\y)});
    \end{scope}
  }
\end{tikzpicture}
\end{document}

Avec Tikz cela m'a l'air laborieux