How to draw cubic shapes on LateX

Question

I have been trying to get my head around drawing on latex and have not been able to get anywhere. I was just wondering if anyone could help me with the following shape? Just need a bit of guidance still quite new to the program.

Answer 1

The following solution uses the experimental(?) package tikz3d.sty from the TeX.SX launchpad. To install it, do the following:

1. Download tikz3d.dtx from http://bazaar.launchpad.net/~tex-sx/tex-sx/development/view/head:/tikz3d.dtx.

2. Run pdflatex on the dtx file to extract tikz3d.sty.

   pdflatex tikz3d.dtx
   

3. Run pdflatex once more on tikz3d.dtx to obtain tikz3d.pdf, the documentation of the package.

Now pdflatexing the following code should result in the picture above.

\documentclass{minimal}
\usepackage{tikz}
\usepackage{tikz3d}
\begin{document}
\begin{center}
\begin{tikzpicture}[3d/perspective eye={0,5,-10},>=stealth]
\newcommand\xa{5} % half of width at bottom
\newcommand\xb{2} % half of width at top
\newcommand\ya{2} % height
\newcommand\za{2} % half of depth
\coordinate (A) at (3d cs:-\xa,0,-\za);
\coordinate (B) at (3d cs: \xa,0,-\za);
\coordinate (C) at (3d cs: \xa,0, \za);
\coordinate (D) at (3d cs:-\xa,0, \za);
\coordinate (E) at (3d cs:-\xb,\ya, 0);
\coordinate (F) at (3d cs: \xb,\ya, 0);
\draw[thick] (D) -- node[left]{$w$} (A) -- node[below]{$l$} (B) -- (C);
\draw[dashed] (C) -- (D);
\draw[thick] (A) -- (E) -- (D);
\draw[thick] (B) -- (F) -- (C);
\draw[thick] (E) -- node[above]{$t$} (F);
\draw[<->,dashed] (3d cs:1,0,0) -- node[right]{$h$} (3d cs:1,\ya,0);
\end{tikzpicture}
\vspace{1cm}

\begin{tikzpicture}[3d/perspective eye={0,5,-10}]
\newcommand\xa{6} % half of width at bottom, shifted
\newcommand\xb{2} % half of width at top
\newcommand\xc{3} % half of width at top, shifted
\newcommand\ya{2} % height
\newcommand\za{2} % half of depth
\coordinate (A) at (3d cs:-\xa,0,-\za);
\coordinate (B) at (3d cs: \xa,0,-\za);
\coordinate (C) at (3d cs: \xa,0, \za);
\coordinate (D) at (3d cs:-\xa,0, \za);
\coordinate (E) at (3d cs:-\xb,\ya, 0);
\coordinate (F) at (3d cs: \xb,\ya, 0);
\coordinate (E') at (3d cs:-\xc,\ya, 0);
\coordinate (F') at (3d cs: \xc,\ya, 0);
\coordinate (a) at (3d cs:-\xb,0,-\za);
\coordinate (b) at (3d cs: \xb,0,-\za);
\coordinate (c) at (3d cs: \xb,0, \za);
\coordinate (d) at (3d cs:-\xb,0, \za);
\coordinate (a') at (3d cs:-\xc,0,-\za);
\coordinate (b') at (3d cs: \xc,0,-\za);
\coordinate (c') at (3d cs: \xc,0, \za);
\coordinate (d') at (3d cs:-\xc,0, \za);
\draw[thick] (a') -- (A) -- (D) -- (E') -- (A);
\draw[dashed] (d') -- (D);
\draw[thick,fill=gray] (a') -- (E') -- (d') -- cycle;
\draw[thick] (b') -- (B) -- (C) -- (F') -- (B);
\draw[dashed] (c') -- (C);
\draw[thick,fill=gray] (b') -- (F') -- (c') -- cycle;
\draw[thick] (a) -- (b) -- (F) -- (E) -- (a);
\draw[dashed] (a) -- (d) -- (c) -- (b);
\draw[dashed] (d) -- (E);
\draw[dashed] (c) -- (F);
\end{tikzpicture}
\end{center}
\end{document}

The code can be simplified by setting the coordinate system globally to 3d cs. If you include the lines

\makeatletter
\def\tikz@parse@splitxyz#1#2#3,#4,{%
    \def\@next{\tikz@scan@one@point#1(3d cs:{#2},{#3},{#4})}%
}
\makeatother

in the preamble, then you can remove the prefix 3d cs: in all of the coordinates, writing e.g. just (-\xa,0,-\za) instead of (3d cs:-\xa,0,-\za).