[Tex/LaTex] Are there simple ways to draw parallelepipeds in tikz

Question

I'm trying to draw some parallelepipeds in tikz and find the task surprisingly frustrating. For example, I'd like to recreate this figure from wikipedia:

I've found lots of tikz examples of cubes but none of parallelepipeds. Is there a simple way to do this?

Answer 1

Maybe this goes in the right direction.

\documentclass[tikz,border=3mm]{standalone}
\begin{document}
\begin{tikzpicture}
 \begin{scope}[x={(4cm,0cm)},y={({cos(30)*1.5cm},{sin(30)*1.5cm})},
    z={({cos(70)*2cm},{sin(70)*2cm})},line join=round,fill opacity=0.5,thick]
  \draw[fill=cyan] (0,0,0) -- (0,0,1) -- (0,1,1) -- (0,1,0) -- cycle;
  \draw[fill=red] (0,0,0) -- (1,0,0) -- (1,1,0) -- (0,1,0) -- cycle;
  \draw[fill=orange] (0,1,0) -- (1,1,0) -- (1,1,1) -- (0,1,1) -- cycle;
  \draw[fill=cyan] (1,0,0) -- (1,0,1) -- (1,1,1) -- (1,1,0) -- cycle;
  \draw[fill=red] (0,0,1) -- (1,0,1) -- (1,1,1) -- (0,1,1) -- cycle;
  \draw[fill=orange] (0,0,0) -- (1,0,0) -- (1,0,1) -- (0,0,1) -- cycle;
 \end{scope}
\end{tikzpicture}
\end{document}

For a more easy to customize solution (with a less "simple" code) consider:

\documentclass[tikz,border=3mm]{standalone}
\tikzset{pics/parallelepiped/.style={code={
 \tikzset{parallelepiped/.cd,#1}
 \begin{scope}[x={(\pgfkeysvalueof{/tikz/parallelepiped/a}*1cm,0cm)},
  y={({cos(\pgfkeysvalueof{/tikz/parallelepiped/theta})*\pgfkeysvalueof{/tikz/parallelepiped/b}*1cm},
    {sin(\pgfkeysvalueof{/tikz/parallelepiped/theta})*\pgfkeysvalueof{/tikz/parallelepiped/b}*1cm})},
    z={({cos(\pgfkeysvalueof{/tikz/parallelepiped/phi})*\pgfkeysvalueof{/tikz/parallelepiped/c}*1cm},
    {sin(\pgfkeysvalueof{/tikz/parallelepiped/phi})*\pgfkeysvalueof{/tikz/parallelepiped/c}*1cm})}
    ,/tikz/parallelepiped/pstyle,pic actions,
    declare function={mysign(\x)=ifthenelse(\x<0,-1,1);}]
  \path[parallelepiped/fall,parallelepiped/fxz] (0,1,0) -- (1,1,0) -- (1,1,1) -- (0,1,1) -- cycle;
  \path[parallelepiped/fall,parallelepiped/fyz,shift={({0.5-0.5*mysign(cos(\pgfkeysvalueof{/tikz/parallelepiped/phi}))},0,0)}] 
    (0,0,0) -- (0,0,1) -- (0,1,1) -- (0,1,0) -- cycle;
  \path[parallelepiped/fall,parallelepiped/fxy,shift={(0,0,{0.5-0.5*mysign(sin(\pgfkeysvalueof{/tikz/parallelepiped/theta}))},0,0)}] 
  (0,0,0) -- (1,0,0) -- (1,1,0) -- (0,1,0) -- cycle;
  \path[parallelepiped/fall,parallelepiped/fyz,shift={({0.5+0.5*mysign(cos(\pgfkeysvalueof{/tikz/parallelepiped/phi}))},0,0)}] 
    (0,0,0) -- (0,0,1) -- (0,1,1) -- (0,1,0) -- cycle;
  \path[parallelepiped/fall,parallelepiped/fxy,shift={(0,0,{0.5+0.5*mysign(sin(\pgfkeysvalueof{/tikz/parallelepiped/theta}))},0,0)}] 
  (0,0,0) -- (1,0,0) -- (1,1,0) -- (0,1,0) -- cycle;
  \path[parallelepiped/fall,parallelepiped/fxz] (0,0,0) -- (1,0,0) -- (1,0,1) -- (0,0,1) -- cycle;
 \end{scope}}},parallelepiped/.cd,a/.initial=4,b/.initial=1.5,c/.initial=2,
 theta/.initial=30,phi/.initial=70,pstyle/.style={draw,thick,fill opacity=0.6,
 line join=round},fall/.style={draw},all
 faces/.code={\tikzset{parallelepiped/fall/.style={#1}}},
 fxy/.style={fill=red},xy face/.code={\tikzset{parallelepiped/fxy/.style={#1}}},
 fxz/.style={fill=orange},xz face/.code={\tikzset{parallelepiped/fxz/.style={#1}}},
 fyz/.style={fill=cyan},yz face/.code={\tikzset{parallelepiped/fyz/.style={#1}}}}
\begin{document}
\begin{tikzpicture}
 \path (0,0) pic{parallelepiped}
   (0,-4) pic{parallelepiped={a=3,phi=110,xz face={fill=yellow}}};
\end{tikzpicture}

\begin{tikzpicture} 
\path (0,-4) pic{parallelepiped={a=4,phi=90,xz face={fill=yellow}}}; 
\end{tikzpicture} 
\end{document}

To the best of my knowledge, as long as there is no 3dshapes.meta library, having a highly customizable 3d-like shape always will require some not-so-simple code. (I am considering making the automatic 3d ordering of planes of the 3dtools library at a given point.)

EDIT: Fixed issue with 90 degree angle, big thanks to @ minhthien_2016!