Drawing a torus with critical points

Question

I want to get something like this but without the plane V (So only the torus vertically and the four critical points s,r,q and p ). I don't have any experience with drawing things with Latex. Any help would be appreciated.

See https://tex.stackexchange.com/q/348/232027 – Jan 04 '21 at 00:48 — , Jan 04 '21 at 00:48
Does this answer your question? How to draw a torus – Roland Jan 04 '21 at 00:56 — Roland, Jan 04 '21 at 00:56
I can't figure out how to draw the points on the torus. – mino Jan 04 '21 at 00:57 — mino, Jan 04 '21 at 00:57

score 1 · Accepted Answer · answered Jan 05 '21 at 10:43

As @Roland suggested, you could use the following solution, and simply add points to it.

\documentclass[tikz,border=7pt]{standalone}
\begin{document}
  \begin{tikzpicture}
  \useasboundingbox (-3,-1.5) rectangle (3,1.5);
  \draw (0,0) ellipse (3 and 1.5);
  \begin{scope}
    \clip (0,-1.8) ellipse (3 and 2.5);
    \draw (0,2.2) ellipse (3 and 2.5);
  \end{scope}
  \begin{scope}
    \clip (0,2.2) ellipse (3 and 2.5);
    \draw (0,-2.2) ellipse (3 and 2.5);
  \end{scope}
  \draw[text=violet] (3,0) node{\Huge{.}} node[above]{A};
  \draw[text=violet] (1.4,0) node{\Huge{.}} node[above]{B};
  \draw[text=violet] (-1.4,0) node{\Huge{.}} node[above]{C};
  \draw[text=violet] (-3,0) node{\Huge{.}} node[above]{D};
\end{tikzpicture}
\end{document}

Drawing a torus with critical points

1 Answers1