[Tex/LaTex] Lines and circles are not visible. Why not

Question

I'm running TeXworks and MikTeX on Microsoft Windows and within a document I have the code you see below. Compiling results in a pdf file in which I can see the text within this picture but I can't see the line or the circles. Nonetheless when I print it the line and the circles are there. Is there something I can do differently to make the line and the circles visible?

\setlength{\unitlength}{0.66mm}

\begin{picture}(100,100)(0,0)

\label{picture of bitangent plane}

\put(40,50){\circle{60}}      % left big circle

\put(140,50){\circle{60}}     % right big circle

\put(122,74){\circle*{2}}     % dot at e^{i\theta} on right circle

\put(122,26){\circle*{2}}     % dot at e^{-i\theta} on right circle

\put(58,26){\circle*{2}}      % dot at e^{-i\theta} on left circle

\put(70,50){\circle*{2}}      % dot at -1 on left circle

\put(38,11){\line(4,3){104}}  % line

\put(140,80){\circle*{2}}     % dot at i on right circle

\put(140,20){\circle*{2}}     % dot at -i on right circle

\put(170,50){\circle*{2}}     % dot at 1 on right circle

\put(110,50){\circle*{2}}     % dot at -1 on right circle

\put(10,50){\circle*{2}}      % dot at 1 on left circle

\put(40,80){\circle*{2}}      % dot at i on left circle

\put(40,20){\circle*{2}}      % dot at -i on left circle

\put(58,74){\circle*{2}}      % dot at e^{i\theta} on left circle

\put(116,76){$e^{i\theta}$}   % right

\put(115,19){$e^{-i\theta}$}  % right

\put(62,76){$e^{i\theta}$}

\put(59,19){$e^{-i\theta}$}   % left

\put(173,49){$1$}  \put(5,49){$1$}

\put(101,49){$-1$} \put(72,49){$-1$}

\put(140,83){$i$}  \put(40,83){$i$}

\put(137,14){$-i$} \put(35,14){$-i$}

\put(70,5){\text{The bitangent plane.}}

\end{picture}

Answer 1

Your circles are too small and you get warnings:

LaTeX Warning: \oval, \circle, or \line size unavailable on input line 6.
LaTeX Warning: \oval, \circle, or \line size unavailable on input line 7.

Load the pict2e package.

I also fixed the bounding box and put the picture in a figure environment. Your \label command is out of place where you put it.

\documentclass{article}
\usepackage{pict2e}
\begin{document}

\begin{figure}
\centering
\setlength{\unitlength}{0.66mm}
\begin{picture}(180,100)(0,0)
\put(40,50){\circle{60}}      % left big circle
\put(140,50){\circle{60}}     % right big circle
\put(122,74){\circle*{2}}     % dot at e^{i\theta} on right circle
\put(122,26){\circle*{2}}     % dot at e^{-i\theta} on right circle
\put(58,26){\circle*{2}}      % dot at e^{-i\theta} on left circle
\put(70,50){\circle*{2}}      % dot at -1 on left circle
\put(38,11){\line(4,3){104}}  % line
\put(140,80){\circle*{2}}     % dot at i on right circle
\put(140,20){\circle*{2}}     % dot at -i on right circle
\put(170,50){\circle*{2}}     % dot at 1 on right circle
\put(110,50){\circle*{2}}     % dot at -1 on right circle
\put(10,50){\circle*{2}}      % dot at 1 on left circle
\put(40,80){\circle*{2}}      % dot at i on left circle
\put(40,20){\circle*{2}}      % dot at -i on left circle
\put(58,74){\circle*{2}}      % dot at e^{i\theta} on left circle
\put(116,76){$e^{i\theta}$}   % right
\put(115,19){$e^{-i\theta}$}  % right
\put(62,76){$e^{i\theta}$}
\put(59,19){$e^{-i\theta}$}   % left
\put(173,49){$1$}  \put(5,49){$1$}
\put(101,49){$-1$} \put(72,49){$-1$}
\put(140,83){$i$}  \put(40,83){$i$}
\put(137,14){$-i$} \put(35,14){$-i$}
\end{picture}
\caption{The bitangent plane}\label{fig:bitangentplane}
\end{figure}
\end{document}