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?
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 :)
The pgf manual has a tutorial called "Putting it in Chains". It starts with an example, which does what you're looking for.
EDIT:
Since the PGF/TikZ manual has a small hyperlink problem due to a typo here is an example of the relevant decoration style random steps. You can customize it further by playing around with the segment length which adjusts the chunks that go in the random direction and amplitude which controls the maximum distance between random step and the main path.
Sample/Simple Example Style:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations.pathmorphing}
\begin{document}
\begin{tikzpicture}[pencildraw/.style={
black!75,
decorate,
decoration={random steps,segment length=0.8pt,amplitude=0.1pt}
}
]
\node[pencildraw,draw] {Node};
\draw[pencildraw] (0,1) -- (1,1) arc (0:-180:9mm and 7mm);
\end{tikzpicture}
\end{document}
This is another attempt to simulate hand drawn curves in Metapost. This is heavily inspired by the MetaFun macros. The main advantage of this approach is that you don't have change your drawing macros at all. Simply input the file and call sketchypaths, and all paths become a bit sketchy.
Save the following as mp-sketch.mp
%D The variable \type{sketch_amount} determines the amount of randomness in the
%D drawing
numeric sketch_amount; sketch_amount := 3bp;
%D The macro \type{sketchdraw} randomized the path before drawing it. The
%D \type{expr} ... \type{text} trick is copied from the definition of
%D \type{drawarrow}
def sketchdraw expr p =
do_sketchdraw(p if (path p): randomized sketch_amount fi)
enddef;
def do_sketchdraw(expr p) text t =
normaldraw p t ;
enddef;
%D The macro \type{sketchfill} randomizes the path before filling it.
path _sketch_path_;
def sketchfill expr p =
_sketch_path_ := p randomized sketch_amount;
do_sketchfill
enddef ;
def do_sketchfill text t =
normalfill _sketch_path_ t ;
enddef ;
%D The macro \type{sketchypaths} is modeled after \type{visualizepaths} from
%D \filename{mp-tool}.
def sketchypaths =
let draw = sketchdraw ;
let fill = sketchfill ;
enddef ;
The main macro is sketchypaths which changes the definition of draw and fill to be sketchy. To recover the normal behavior use the naturalizepahts macro from metafun.
To use these, you also need to load mp-tool.mkiv. I'll show a test file in ConTeXt, which already loads the MetaFun macros.
\startMPinclusions
input mp-sketch;
\stopMPinclusions
\starttext
\startMPpage[offset=3mm]
sketchypaths;
draw (0,0) -- (1cm,0) -- (1cm,1cm);
fill fullsquare scaled 1cm shifted (3cm,3cm) withcolor red;
drawarrow (1cm,1cm) -- (2cm,2cm);
stripe_path_a
(withcolor red)
(draw)
fullcircle xscaled 100 yscaled 40 shifted (0, 2.5cm) withcolor blue;
\stopMPpage
\stoptext
which gives
Since the sketchypaths macro changes the draw and fill commands, it is easy to combine this with existing MetaPost packages. For example, to use boxes.mp:
\startMPdefinitions
input mp-sketch;
input boxes;
\stopMPdefinitions
\starttext
\startMPpage[offset=3mm]
sketchypaths;
boxit.one (btex One etex);
boxit.two (btex Two etex);
boxit.three (btex Three etex);
three.w - two.e = two.w - one.e = (1cm,0);
one.c = origin;
drawboxed (one, two, three);
drawarrow one.e -- lft two.w;
drawarrow two.e -- lft three.w;
\stopMPpage
\stoptext
The figure on the top shows the output without sketchypaths and the figure on the bottom shows the output with sketchyparts.
And here is a slightly tweaked version of example 83 of metapost examples
In my biased opinion, this looks more natural than many of the other solutions.
mp-tool.mkiv in LaTeX?
Commented
Sep 29, 2019 at 1:59
Only for the fun, I took Marc's suggestion and I create a new decoration free hand with fixed parameters, a new style free hand and a new macro freedraw
\documentclass[border=1cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{decorations.pathmorphing}
\begin{document}
\pgfdeclaredecoration{free hand}{start}
{
\state{start}[width = +0pt,
next state=step,
persistent precomputation = \pgfdecoratepathhascornerstrue]{}
\state{step}[auto end on length = 3pt,
auto corner on length = 3pt,
width=+2pt]
{
\pgfpathlineto{
\pgfpointadd
{\pgfpoint{2pt}{0pt}}
{\pgfpoint{rand*0.15pt}{rand*0.15pt}}
}
}
\state{final}
{}
}
\tikzset{free hand/.style={
decorate,
decoration={free hand}
}
}
\def\freedraw#1;{\draw[free hand] #1;}
\begin{tikzpicture}
\freedraw [->](-5,0) -- (5,0);
\freedraw [->](0,-5) -- (0,5);
\freedraw[fill=blue!15,fill opacity=.25] (-3,-3) rectangle (3,3);
\freedraw[fill=green!15,fill opacity=.25] circle [radius=3cm];
\freedraw[free hand,red,shift={(1,1)},rotate=45,fill=red!25,fill opacity=.5] %
(1,1) -- (1,-1) -- (-1,-1) -- (-1,1) -- (1,1);
\freedraw[color=blue] plot (\x,{sin(\x r)}) node [free hand,draw] {$\sin(x)$} ;
\end{tikzpicture}
\end{document}
[EDIT on August 13, 2018: better and shorter code, but unfortunately a lot slower now...]
I realize I'm a bit late to the party, but here's my attempt. I tried to implement the ideas they used in matplotlib to create an "XKCD" style. Example code and images below.
It's the first time I wrote code at the PGF level, so I'm happy to receive corrections and/or suggestions.
The code needs LuaLaTeX for the fonts, but if you remove the font stuff it should work with normal LaTeX as well.
\documentclass{article}
\usepackage{fontspec}
\setmainfont{Humor Sans}
\usepackage{tikz}
\usetikzlibrary{calc,decorations,patterns,arrows,decorations.pathmorphing}
\definecolor{pltblue}{HTML}{1F77B4}
\makeatletter
\pgfset{
/pgf/decoration/randomness/.initial=2,
/pgf/decoration/wavelength/.initial=100
}
\pgfdeclaredecoration{sketch}{init}{
\state{init}[width=0pt,next state=draw,persistent precomputation={
\pgfmathsetmacro\pgf@lib@dec@sketch@t0
}]{}
\state{draw}[width=\pgfdecorationsegmentlength,
auto corner on length=\pgfdecorationsegmentlength,
persistent precomputation={
\pgfmathsetmacro\pgf@lib@dec@sketch@t{mod(\pgf@lib@dec@sketch@t+pow(\pgfkeysvalueof{/pgf/decoration/randomness},rand),\pgfkeysvalueof{/pgf/decoration/wavelength})}
}]{
\pgfmathparse{sin(2*\pgf@lib@dec@sketch@t*pi/\pgfkeysvalueof{/pgf/decoration/wavelength} r)}
\pgfpathlineto{\pgfqpoint{\pgfdecorationsegmentlength}{\pgfmathresult\pgfdecorationsegmentamplitude}}
}
\state{final}{}
}
\tikzset{xkcd/.style={decorate,decoration={sketch,segment length=0.5pt,amplitude=0.5pt}}}
\makeatother
\pgfmathsetseed{1}
\pagestyle{empty}
\begin{document}
\renewcommand{\baselinestretch}{0.85}
\begin{center}
\begin{tikzpicture}[xscale=4, yscale=0.05]
\node at (0.5,115) {\large Claims of supernatural powers};
\begin{scope}[very thick, every path/.style={xkcd}]
\fill[fill=pltblue] (0.875,1) -- ++(0,99) -- ++(0.25,0) -- +(0,-99) -- cycle;
\draw (0.875,1) -- ++(0,99) -- ++(0.25,0) -- +(0,-99);
\draw[ultra thick] (0,3) -- (0,0) node[below, text width=3cm, align=center] {confirmed by\\ experiment};
\draw[ultra thick] (1,3) -- (1,0) node[below, text width=3cm, align=center] {refuted by\\ experiment};
\draw (-0.5,0) -- (1.5,0);
\draw (-0.5,0) -- (-0.5,110);
\end{scope}
\end{tikzpicture}
\vspace{2cm}
\begin{tikzpicture}[xscale=0.08, yscale=0.15]
\node at (35,12) {\large Stove ownership};
\node[rotate=90] at (-3,-12) {My overall health};
\node[text width=4cm] (N) at (40, -8) {The day I realized\\ I could cook bacon\\ whenever I wanted};
\begin{scope}[very thick, every path/.style={xkcd}]
\draw (0,-30) -- node[below] {Time} (100,-30);
\draw (0,-30) -- (0,10);
\draw[pltblue] (1,1) -- (70,1) -- (100,-28);
\draw[->, >=stealth'] ($(N.north)+(5cm,0)$) -- (69.5,0.5);
\end{scope}
\end{tikzpicture}
\end{center}
\begin{center}
\begin{tikzpicture}
\draw[xkcd,help lines] (-2,-2) grid[step=1cm] (4,4);
\draw[xkcd,thick] (0,0) -- (0,3) -- (3,3);
\draw[xkcd,ultra thick, blue] (3,3) arc (0:-90:2cm);
\draw[xkcd,thick, pattern=north east lines] (-0.4cm,-0.8cm) rectangle (1.2,-2);
\node[xkcd, draw, inner sep=0.5cm, fill=yellow, circle] (a) at (2,0) {};
\node[xkcd,draw, inner sep=0.3cm, fill=red] (b) at (2,-2) {};
\draw[xkcd] (b) to[in=-45,out=45] (a);
\node[xkcd,draw, minimum height=2cm, minimum width=1cm] (c) at (-1.5,0) {};
\draw[xkcd,->, decoration={post=lineto, post length=5mm}, dashed] (-0.5cm,-0.5cm) -- (-0.5cm,3.5cm) -| (c.north);
\end{tikzpicture}
\vspace{2cm}
\begin{tikzpicture}[very thick, yscale=2, every path/.style={xkcd}]
\draw (-0.3,-1.2) rectangle (7.3,1.2);
\foreach \y in {-1.00,-0.75,...,1.00} {
\draw[ultra thick] (-0.3,\y) -- (-0.4,\y) node[left] {\pgfmathprintnumber[fixed,fixed zerofill,precision=2,assume math mode=true]{\y}};
}
\foreach \x in {0,...,7} {
\draw[ultra thick] (\x,-1.2) -- (\x,-1.25) node[below] {\x};
}
\draw[domain=0:7, pltblue, samples=100] plot (\x, {sin(\x r)});
\end{tikzpicture}
\end{center}
\end{document}
In terms of regular (straight) lines, pstricks-add offers
\pslineByHand[<options>](<x1>,<y1>)(<x2>,<y2>)(<x3>,<y3>)...
that draws a straight line with some "jagging." The "jagging" parameters that influence the line drawing are VarStepEpsilon (default is 2) and varsteptol (default is 0.8).
\documentclass{article}
\usepackage{xcolor}% http://ctan.org/pkg/xcolor
\usepackage{pstricks-add}% http://ctan.org/pkg/pstricks-add
\begin{document}
\begin{pspicture}(11,3)
\psset{unit=1cm,linewidth=0.5pt,linecolor=black!70,linejoin=1}
\psline(0,0)(0,2)(2,2)(2,0)(0,0)(2,2)(1,3)(0,2)(2,0)% Regular HOUSE with straight lines
\rput(3,0){\pslineByHand(0,0)(0,2)(2,2)(2,0)(0,0)(2,2)(1,3)(0,2)(2,0)}
\rput(6,0){\pslineByHand[VarStepEpsilon=4](0,0)(0,2)(2,2)(2,0)(0,0)(2,2)(1,3)(0,2)(2,0)}
\rput(9,0){\pslineByHand[varsteptol=0.2](0,0)(0,2)(2,2)(2,0)(0,0)(2,2)(1,3)(0,2)(2,0)}
\end{pspicture}
\end{document}
This requires a latex->dvips->ps2pdf or xelatex compile sequence.
Here are two pens with MetaPost (using ConTeXt format), I feel the code is pretty self-explanatory:
\starttext
\startMPenvironment
color lightgray ; lightgray := (.8,.8,.8) ;
color darkgray ; darkgray := (.2,.2,.2) ;
\stopMPenvironment
Pen based on a circle:
\startMPcode
z0 = (0.5cm,1.5cm) ; z1 = (2.5cm,2.5cm) ;
z2 = (6.5cm,0.5cm) ; z3 = (3.0cm,1.5cm) ;
pickup pencircle xscaled 2mm yscaled 4mm rotated 30 ;
draw z0..z1..z2..z3..z0..cycle withcolor lightgray ;
\stopMPcode
\bigskip
Pen based on a diamond:
\startMPcode
z0 = (0.5cm,1.5cm) ; z1 = (2.5cm,2.5cm) ;
z2 = (6.5cm,0.5cm) ; z3 = (3.0cm,1.5cm) ;
pickup pensquare xyscaled 2mm rotated 45 ;
draw z0..z1..z2..z3...z0..cycle withcolor darkgray ;
\stopMPcode
\stoptext
This is the first time I have used MetaPost with ConTeXt, and was happy how to see how easy it is to use.
Based on Marcs solution I tried to mimic the ps-tricks results (randomized/imprecise coordinates) shown by Werner using tikz:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations.pathmorphing}
\begin{document}
\begin{tikzpicture}[pencildraw/.style={
black!75,
decorate,
decoration={random steps,segment length=2pt,amplitude=0.3pt},
to path={ -- ([xshift=rand*1mm, yshift=rand*1mm] \tikztotarget) \tikztonodes}
}
]
\draw[pencildraw] (0,0) to (0,2) to (2,2) to (2,0) to (0,0) to (2,2) to
(1,3) to (0,2) to (2,0);
\end{tikzpicture}
\end{document}
Maybe someone can improve this, i.e. find a more general way to randomize coordinates, as this solution for example will not randomize all corners of a rectangle automatically.
There are lots of nice answers here addressing how to get that "hand drawn" look with the shape of the lines. I'm going to sketch an approach to getting the texture right. I spent a bit of time this afternoon staring at some lines drawn with a 9B pencil on paper and decided that what it looked most like was a brass rubbing. That is, the stroke of the pencil reveals the texture of the paper underneath. This is most like a fading in TikZ/PGF parlance.
The cheap and nasty paper that I buy doesn't have much of a grain to it (I have kids, they do art, I buy about 5 reams every six months). The pattern looks more like noise. So having learnt about Perlin noise recently, I thought that would be an appropriate thing to simulate the paper texture with. I soon decided that a TeX implementation would be daft, so went hunting for a Lua version and found one of the closely related Simplex noise (also due to Perlin; the link goes to a Lua implementation; the author uses strong language both in comments and function names). So I hacked that into a Lua file for LuaTeX and wrote a little demonstration LaTeX file.
I'm calling this an approach because it needs considerable work to be useful. For one thing, even though I'm using Lua to do the heavy processing then it takes time to render the fading. So given that noise isn't usually required to be too random, one should do a lot of caching: both of the original generated numbers and the graphic used for the fading itself. There's also a fair bit about fadings that I don't understand, particularly related to how the fading and the picture match up.
What should happen is that one uses one fading for the whole picture so that strokes laid over each other end up using the same noise and thus work as though they are on top of the same piece of paper. This would also need a little work to do with positioning.
The code isn't too complicated. Here's the LaTeX file:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{fadings}
\directlua{
dofile('tikzgraphite.lua')
}
\makeatletter
\tikzset{show bounding box/.code={
\message{^^JBounding box is (\the\pgf@picminx,\the\pgf@picminy) to (\the\pgf@picmaxx,\the\pgf@picmaxy)^^J}
}
}
\makeatother
\begin{document}
\begin{tikzfadingfrompicture}[name=graphite]
\foreach \i in {0,...,160} \foreach \j in {0,...,40}
\fill[transparent! \directlua{tex.print(math.floor(50*(Noise2D(\i,\j)+1)))}] (\i pt, \j pt) rectangle (\i + 1 pt, \j + 1 pt);
\end{tikzfadingfrompicture}
\begin{tikzpicture}
\draw[path fading=graphite,fit fading=false,fading transform={shift={(70pt,15pt)}},line width=.5cm,line cap=round,black!75] (0,0) to[bend left] (5,0);
\tikzset{show bounding box}
\end{tikzpicture}
\end{document}
The show bounding box key is so that I can get an idea of how big to make the fading. I don't want to scale it as I want a good texture, and I don't want to generate it too big as it takes a looooonnnnnggggg time to render.
Here's the lua file:
local Gradients3D = {{1,1,0},{-1,1,0},{1,-1,0},{-1,-1,0},
{1,0,1},{-1,0,1},{1,0,-1},{-1,0,-1},
{0,1,1},{0,-1,1},{0,1,-1},{0,-1,-1}}
local simplex = {
{0,1,2,3},{0,1,3,2},{0,0,0,0},{0,2,3,1},{0,0,0,0},{0,0,0,0},{0,0,0,0},{1,2,3,0},
{0,2,1,3},{0,0,0,0},{0,3,1,2},{0,3,2,1},{0,0,0,0},{0,0,0,0},{0,0,0,0},{1,3,2,0},
{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},
{1,2,0,3},{0,0,0,0},{1,3,0,2},{0,0,0,0},{0,0,0,0},{0,0,0,0},{2,3,0,1},{2,3,1,0},
{1,0,2,3},{1,0,3,2},{0,0,0,0},{0,0,0,0},{0,0,0,0},{2,0,3,1},{0,0,0,0},{2,1,3,0},
{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},
{2,0,1,3},{0,0,0,0},{0,0,0,0},{0,0,0,0},{3,0,1,2},{3,0,2,1},{0,0,0,0},{3,1,2,0},
{2,1,0,3},{0,0,0,0},{0,0,0,0},{0,0,0,0},{3,1,0,2},{0,0,0,0},{3,2,0,1},{3,2,1,0}}
local p = {151,160,137,91,90,15,
131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180}
for i=1,#p do
p[i-1] = p[i]
p[i] = nil
end
for i=1,#Gradients3D do
Gradients3D[i-1] = Gradients3D[i]
Gradients3D[i] = nil
end
local perm = {}
for i=0,255 do
perm[i] = p[i]
perm[i+256] = p[i]
end
function Dot2D(tbl, x, y)
return tbl[1]*x + tbl[2]*y;
end
local Prev2D = {}
-- 2D simplex noise
function Noise2D(xin, yin)
if Prev2D[xin] and Prev2D[xin][yin] then return Prev2D[xin][yin] end
local n0, n1, n2; -- Noise contributions from the three corners
-- Skew the input space to determine which simplex cell we're in
local F2 = 0.5*(math.sqrt(3.0)-1.0);
local s = (xin+yin)*F2; -- Hairy factor for 2D
local i = math.floor(xin+s);
local j = math.floor(yin+s);
local G2 = (3.0-math.sqrt(3.0))/6.0;
local t = (i+j)*G2;
local X0 = i-t; -- Unskew the cell origin back to (x,y) space
local Y0 = j-t;
local x0 = xin-X0; -- The x,y distances from the cell origin
local y0 = yin-Y0;
-- For the 2D case, the simplex shape is an equilateral triangle.
-- Determine which simplex we are in.
local i1, j1; -- Offsets for second (middle) corner of simplex in (i,j) coords
if(x0>y0) then
i1=1
j1=0 -- lower triangle, XY order: (0,0)->(1,0)->(1,1)
else
i1=0
j1=1 -- upper triangle, YX order: (0,0)->(0,1)->(1,1)
end
-- A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
-- a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
-- c = (3-sqrt(3))/6
local x1 = x0 - i1 + G2; -- Offsets for middle corner in (x,y) unskewed coords
local y1 = y0 - j1 + G2;
local x2 = x0 - 1.0 + 2.0 * G2; -- Offsets for last corner in (x,y) unskewed coords
local y2 = y0 - 1.0 + 2.0 * G2;
-- Work out the hashed gradient indices of the three simplex corners
local ii = i%256
local jj = j%256
local gi0 = perm[ii+perm[jj]] % 12;
local gi1 = perm[ii+i1+perm[jj+j1]] % 12;
local gi2 = perm[ii+1+perm[jj+1]] % 12;
-- Calculate the contribution from the three corners
local t0 = 0.5 - x0*x0-y0*y0;
if t0<0 then
n0 = 0.0;
else
t0 = t0 * t0
n0 = t0 * t0 * Dot2D(Gradients3D[gi0], x0, y0); -- (x,y) of Gradients3D used for 2D gradient
end
local t1 = 0.5 - x1*x1-y1*y1;
if (t1<0) then
n1 = 0.0;
else
t1 = t1*t1
n1 = t1 * t1 * Dot2D(Gradients3D[gi1], x1, y1);
end
local t2 = 0.5 - x2*x2-y2*y2;
if (t2<0) then
n2 = 0.0;
else
t2 = t2*t2
n2 = t2 * t2 * Dot2D(Gradients3D[gi2], x2, y2);
end
-- Add contributions from each corner to get the final noise value.
-- The result is scaled to return values in the localerval [-1,1].
local retval = 70.0 * (n0 + n1 + n2)
if not Prev2D[xin] then Prev2D[xin] = {} end
Prev2D[xin][yin] = retval
return retval;
end
It is almost entirely just clipped out from the lua implementation linked above. There's no obvious licence information there, but consider it covered under whatever-licence-it-would-be-there.
Here's the result of that code:
Has anyone noticed how it looks more natural when we just superpose lines? I guess that when we hand drawn we are not only introducing a random component, we some times pass the pencil again, maybe with a different pressure. Here an example:
\draw[<-,gray,thick] (0,1) to[bend left=10] ++(1,1);
\draw[<-,gray] (0,1) to[bend left=5] ++(1,1);
For instance, I took the code in the answer of @renard and I have just repeated some lines and shapes:
\draw[penciline={jag ratio=2},style=help lines,thick] (-2,-2) grid[step=1cm] (4,4);
\draw[penciline={jag ratio=2},style=help lines] (-2,-2) grid[step=1cm] (4,4);
\draw[penciline={jag ratio=0},thick] (0,0) -- (0,3) -- (3,3);
\draw[penciline={jag ratio=2}] (0,0) -- (0,3) -- (3,3);
\draw[decorate,thick,pattern=north east lines] (-0.4cm,-0.8cm) rectangle (1.2,-2);
\draw[penciline={jag ratio=0},ultra thick,blue] (3,3) arc (0:-90:2cm);
\node[penciline={jag ratio=0},draw,inner sep=0.5cm,fill=yellow,circle] (a) at (2,0) {};
\node[penciline={jag ratio=0},penciline={jag ratio=0},draw,inner sep=0.5cm,circle] (a) at (2,0) {};
\node[decorate,inner sep=0.3cm,fill=red] (b) at (2,-2) {};
\node[decorate,draw,thick,inner sep=0.3cm,fill=red] (b) at (2,-2) {};
%% This was supposed to be an edge!!
\draw[decorate] (b) to[in=-45,out=45] (a);
\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);
Might a mix of the repetition and the randomness of the other solutions increase the natural sensation?. Note that I also have changed a little the different jag ratio or pressure in the repetitions. Here the result:
I worked on @percusse example and I managed to fix the circle issues. I might be perfectible but I guess the idea is there.
\documentclass[border=1cm]{standalone}
\RequirePackage{tikz}
\usepackage{ifthen}
\usetikzlibrary{calc,patterns,decorations,plotmarks}
\usepackage{pgfplots}
\pgfplotsset{compat=1.8}
\begin{document}
\pgfdeclaredecoration{penciline}{initial}{
\state{initial}[width=+\pgfdecoratedinputsegmentremainingdistance,
auto corner on length=1pt,
]{
\ifthenelse
{\pgfkeysvalueof{/tikz/penciline/jag ratio}=0} {
\pgfpathcurveto%
{% 1st control point
\pgfpoint
{\pgfdecoratedinputsegmentremainingdistance/2}
{2*rnd*\pgfdecorationsegmentamplitude}
}
{%% 2nd control point
\pgfpoint
%% Make sure random number is always between origin and target points
{\pgfdecoratedinputsegmentremainingdistance/2}
{2*rnd*\pgfdecorationsegmentamplitude}
}
{% 2nd point (1st one is implicit)
\pgfpointadd
{\pgfpointdecoratedinputsegmentlast}
{\pgfpoint{0*rand*1pt}{0*rand*1pt}}
}
} {
\pgfpathcurveto%
{% 1st control point
\pgfpoint
{\pgfdecoratedinputsegmentremainingdistance*rnd*1pt}
{\pgfkeysvalueof{/tikz/penciline/jag ratio}*
rand*\pgfdecorationsegmentamplitude}
}
{%% 2nd control point
\pgfpoint
%% Make sure random number is always between origin and target points
{(.5+0.25*rand)*\pgfdecoratedinputsegmentremainingdistance}
{\pgfkeysvalueof{/tikz/penciline/jag ratio}*
rand*\pgfdecorationsegmentamplitude}
}
{% 2nd point (1st one is implicit)
\pgfpointadd
{\pgfpointdecoratedinputsegmentlast}
{\pgfpoint{rand*1pt}{rand*1pt}}
}
}
}
\state{final}{}
}
\tikzset{
penciline/.code={\pgfqkeys{/tikz/penciline}{#1}},
penciline={
jag ratio/.initial=5,
decoration/.initial = penciline,
},
penciline/.style = {
decorate,
%%decoration={\pgfkeysvalueof{/tikz/penciline/decoration}},
penciline/.cd,
#1,
/tikz/.cd,
},
decorate,
decoration={\pgfkeysvalueof{/tikz/penciline/decoration}},
}
\def\Grid{
\draw[penciline={jag ratio=6},style=help lines] (-2,-2) grid[step=1cm] (4,4);
}
\begin{tikzpicture}[penciline={jag ratio=2}]
\Grid{}
\draw[penciline={jag ratio=0},thick] (0,0) -- (0,3) -- (3,3);
\draw[decorate,thick,pattern=north east lines] (-0.4cm,-0.8cm) rectangle (1.2,-2);
\draw[penciline={jag ratio=0},ultra thick,blue] (3,3) arc (0:-90:2cm);
\node[penciline={jag ratio=0},draw,inner sep=0.5cm,fill=yellow,circle] (a) at (2,0) {};
\node[decorate,draw,inner sep=0.3cm,fill=red] (b) at (2,-2) {};
%% This was supposed to be an edge!!
\draw[decorate] (b) to[in=-45,out=45] (a);
\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}
Edit:
Using test from Conditional using non-integer numbers allow to use floats for jag ratio:
...
\ifthenelse
{\lengthtest{\pgfkeysvalueof{/tikz/penciline/jag ratio}pt = 0pt}} {
\pgfpathcurveto%
...
You might want to create a brush (possibly with transparency) and apply it repeatedly on the paths created by the other replies, possibly with some transformations of the brush itself to make it appear even more random. Intensity effects can be achieved with a highly transparent brush and changing "velocity" of the path movement (or changing frequency of applying the brush).
See how a graphite effect is created in this drawing pad, or the airbrush tool in GIMP. I am not an expert in graphics so I cannot give much advice here; my feeling is that you will need to experiment quite a bit to achieve the desired result. (On that note: A sample drawing would help understand your question better.)
You can use marking decorations (Section 30.4 in the PGF manual). There is also an example that draws arrows along a path, so I'm pretty sure you can do the same thing with a vector or bitmap brush. This has been borrowed from the manual:
\begin{tikzpicture}[decoration={markings,
mark=between positions 0 and 1 step 1cm
with { \node [single arrow,fill=red,
single arrow head extend=3pt,transform shape] {};}}]
\draw [help lines] grid (3,2);
\draw [postaction={decorate}] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
The size of the PDF will not be affected much because TikZ can be instructed to load the brush only once. However, rendering may take quite a while.
