# TikZ drawing (half-dashed circles in different planes)

Although I have ~10 years of LaTeX experience, I never needed any drawings.

I'm trying to make this drawing, TikZ definitely seems like the only way, but I'm really in a hurry and I just can't figure out how to do the 2 circles in different planes, half-dashed. This is the closest I've got so far.

• Welcome. Can you please post your code so that we can fix it right away over that? Jun 13, 2015 at 11:13
• This is how I typically draw the half-dashed circle: \draw[dashed] (00) arc [start angle=0,end angle=180,x radius=3cm, y radius=1cm]; \draw (0,0) arc [start angle=0,end angle=-180,x radius=3cm, y radius=1cm]; Jun 13, 2015 at 11:48
• TikZ is definitely not the only way to produce drawings for LaTeX. If you are in a hurry, then drawing by hand and scanning the result into something you can include with \includegraphics might be easiest. Or drawing it with an interactive tool, like Geogebra. I would only start with TikZ if you have plenty of time to read the excellent manual and learn it. For 3D drawings you could also consider Asymptote, or pstricks. Metapost could also draw your sketch quite nicely since it is fairly simple. Jun 13, 2015 at 11:51

You could try something like this:

\draw (3,0) arc[x radius=3, y radius=1, start angle=0, end angle=-180];


which provides: Change the distances (x radius, y radius, etc.) depending on your drawing. Note that (3,0) is not the center of the arc, but it is the point the arc starts to be drawn.

• That's great! But is there an easy way to pick the plane in which the circle is drawn when you're in a 3-dimensional space? Jun 13, 2015 at 12:37
• @H3llShadow There might be, but I don't know it. Sorry. Maybe you can find something here: tex.stackexchange.com/questions/32077/…. Good luck!!
– Manu
Jun 13, 2015 at 12:48

A PSTricks solution:

\documentclass{article}

\def\circlecut[#1](#2,#3)#4{%
\psellipticarc(#2,#3)(#2,0.3){180}{0}
\psellipticarc[linestyle = dotted](#2,#3)(#2,0.3){0}{180}
\psdot(#2,#3)
\uput{0.07}[#1](#2,#3){\scriptsize #4}%
}

\begin{document}

\begin{pspicture}[dimen = m](-0.45,-0.3)(2.45,5.3) % boundry found manually
\psframe(0,0)(2,3.5)
\uput(0,3.5){$A$}
\uput(2,3.5){$B$}
\uput(2,0){$C$}
\uput(0,0){$D$}
\psline(0,3.5)(1,5)(2,3.5)
\psdot(1,5)
\uput(1,5){$V$}
\circlecut(1,0){$O'$}
\circlecut(1,3.5){$O$}
\end{pspicture}

\end{document} 