[Tex/LaTex] Simulating hand-drawn lines

Question

I am working on a project that will have some vector graphics, perhaps using TikZ (or a similar package). All of the graphics consists of lines, in shades of gray. However, the lines from TikZ appear too clean.

Is there any way to make the lines appear as if they were produced by a graphite pencil?

Answer 1

I'm posting this just because you mentioned specifically the lines.

I modified the bent decoration to make it look like more of a hand drawing. It truly has problems and you can't use it on curves for now... well you can but the result is unexpected at the least.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc,decorations.pathmorphing,patterns}

\makeatletter

\pgfdeclaredecoration{penciline}{initial}{
    \state{initial}[width=+\pgfdecoratedinputsegmentremainingdistance,auto corner on length=1mm,]{
        \pgfpathcurveto%
        {% From
            \pgfqpoint{\pgfdecoratedinputsegmentremainingdistance}
                            {\pgfdecorationsegmentamplitude}
        }
        {%  Control 1
        \pgfmathrand
        \pgfpointadd{\pgfqpoint{\pgfdecoratedinputsegmentremainingdistance}{0pt}}
                        {\pgfqpoint{-\pgfdecorationsegmentaspect\pgfdecoratedinputsegmentremainingdistance}%
                                        {\pgfmathresult\pgfdecorationsegmentamplitude}
                        }
        }
        {%TO 
        \pgfpointadd{\pgfpointdecoratedinputsegmentlast}{\pgfpoint{1pt}{1pt}}
        }
    }
    \state{final}{}
}
\makeatother
\begin{document}
\begin{tikzpicture}[decoration=penciline]
\draw[decorate,style=help lines] (-2,-2) grid[step=1cm] (4,4);
\draw[decorate,thick] (0,0) -- (0,3) -- (3,3);
\draw[decorate,ultra thick,blue] (3,3)  arc (0:-90:2cm); %% This is supposed to be an arc!!
\draw[decorate,thick,pattern=north east lines] (-0.4cm,-0.8cm) rectangle (1.2,-2);
\node[decorate,draw,inner sep=0.5cm,fill=yellow,circle] (a) at (2,0) {}; %% That's not even an ellipse !!
\node[decorate,draw,inner sep=0.3cm,fill=red] (b) at (2,-2) {};
\draw[decorate] (b) to[in=-45,out=45] (a); %% This was supposed to be an edge!!
\node[decorate,draw,minimum height=2cm,minimum width=1cm] (c) at (-1.5,0) {};
\draw[decorate,->,dashed] (-0.5cm,-0.5cm) -- (-0.5cm,3.5cm)  -| (c.north);
\end{tikzpicture}
\end{document}

Here is the output:

I'm currently studying the markings decorations to see how one can move along a path without giving explicit coordinates on the curve. That would hopefully make it possible to use it on arcs. Note that the background grid is also decorated :)