Example: Penrose tiling

% Penrose tiling (P0=Robinson triangle decomposition)
% Author: Paul Gaborit
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{ifthen}
\pgfmathsetmacro{\invphi}{2/(1+sqrt(5))}
\newcommand\penroseA[4]{% n, a, b, c
  \ifthenelse{0<#1}{
    {
      \pgfmathtruncatemacro{\n}{#1-1}
      \coordinate(#2#4) at ($(#2)!\invphi!(#4)$);
      \coordinate(#2#3) at ($(#2)!\invphi!(#3)$);
      \penroseA{\n}{#2}{#2#3}{#2#4}
      \penroseA{\n}{#4}{#2#3}{#3}
      \penroseB{\n}{#2#3}{#4}{#2#4}
    }
  }{
    \fill[colA,draw=white] (#2) -- (#3) -- (#4) -- cycle;
  }
}
\newcommand\penroseB[4]{% n, a, b, c
  \ifthenelse{0<#1}{
    {
      \pgfmathtruncatemacro{\n}{#1-1}
      \coordinate(#2#3) at ($(#2)!\invphi!(#3)$);
      \penroseA{\n}{#2}{#2#3}{#4}
      \penroseB{\n}{#3}{#4}{#2#3}
    }
  }{
    \fill[colB,draw=white] (#2) -- (#3) -- (#4) -- cycle;
  }
}
\begin{document}
\begin{tikzpicture}[line width=.1pt]
  \colorlet{cyan}[rgb]{cyan}
  \colorlet{colB}{red}
  \colorlet{colA}{blue}
  \coordinate (a) at (0,0);
  \path (a) ++(0:15) coordinate (b);
  \path (a) ++(36:15) coordinate (c);
  \path (a) ++(72:15*\invphi) coordinate (d);
  \path (a) ++(-36:15*\invphi) coordinate (e);
  \penroseA{8}{a}{b}{c}  
  \penroseB{8}{c}{a}{d}
  \penroseB{8}{b}{a}{e}
\end{tikzpicture}
\end{document}