packagestikz-pgftikzlibrary
I'm new to LaTeX and this may have been answered somewhere already. But I don't understand why I have to use the command \usetikzlibrary{...}. Why doesn't \usepackage{tikz} give me all the libraries? Are there other packages beside tikz that do a similar thing?
My guess at why it does this is because tikz might be a big library so it doesn't want to load all of it at once? Basically what is the difference between the two?
TikZ is the only full graphics package for TeX I have ever used, so I can't really do a good comparison. However here are some things that I think are worth mentioning:
Some useful programming features, like \foreach or an extensible mathematics engine.
On the other hand, PSTricks has been around for a longer time. In particular, there are lots of libraries built around it. So if you want to use one of the libraries that doesn't (yet) have a TikZ equivalent, you have to use PSTricks. Also I suppose there is better support on older systems, if updating is not possible.
Update: This is now available on CTAN (see above). Bugfixes and improvements will generally be available on github before being uploaded to CTAN. Note that that repository is quite cluttered, the relevant .dtx file is called spath3.dtx. This generates all the necessary files.
Update: The code has undergone considerable revision following extensive discussion with Jamie in the chat room From Answers to Packages. The code can now be downloaded from the TeX-SX Launchpad Project. The necessary files are knots.dtx and spath.dtx. The file knots_test.tex contains some example code. To create the .sty files from the .dtx, run tex <file>.dtx. Alternatively, running latex (or pdflatex) on knots_test.tex with shell escapes enabled will automatically generate the .sty files.
Okay, here's my first attempt at implementing what we discussed in chat. It is certainly a bit rough around the edges, and I give absolutely no guarantees that it won't TeX your cat instead.
Code:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{intersections}
\makeatletter
\newcounter{knot@strings}
\newif\ifknot@draftmode
\tikzoption{save knot path}{\tikz@addmode{\pgfsyssoftpath@getcurrentpath\knot@tmppath\expandafter\global\expandafter\let#1=\knot@tmppath}}
\tikzoption{use knot path}{\tikz@addmode{\expandafter\pgfsyssoftpath@setcurrentpath#1}}
\tikzset{
knot/draft mode/.is if=knot@draftmode
}
\newenvironment{knot}[1][]{%
\tikzset{#1}%
\setcounter{knot@strings}{0}}{%
\foreach \knot@str in {1,...,\the\value{knot@strings}} {
\expandafter\expandafter\expandafter\draw\expandafter\expandafter\expandafter[\csname knot@string@opts@\knot@str\endcsname,use knot path=\csname knot@string@\knot@str\endcsname] (0,0);
\ifknot@draftmode
\begingroup
\let\pgfsyssoftpath@movetotoken=\pgfqpoint
\let\pgfsyssoftpath@linetotoken=\pgfqpoint
\let\pgfsyssoftpath@curvetotoken=\pgfqpoint
\let\pgfsyssoftpath@curvetosupportatoken=\pgfqpoint
\let\pgfsyssoftpath@curvetosupportbtoken=\pgfqpoint
\csname knot@string@\knot@str\endcsname
\global\pgf@xa=\pgf@x
\global\pgf@ya=\pgf@y
\endgroup
\node[circle,fill=white,fill opacity=.5] at (\pgf@xa,\pgf@ya) {\knot@str};
\fi
}
\pgfmathtruncatemacro{\knot@stam}{\the\value{knot@strings}-1}
\foreach \knot@sta in {1,...,\knot@stam} {
\pgfmathtruncatemacro{\knot@stap}{\knot@sta + 1}
\foreach \knot@stb in {\knot@stap,...,\the\value{knot@strings}} {
\pgfintersectionofpaths{\expandafter\pgfsetpath\csname knot@string@\knot@sta\endcsname}{\expandafter\pgfsetpath\csname knot@string@\knot@stb\endcsname}
\foreach \intsect in {1,...,\pgfintersectionsolutions} {
\pgfpointintersectionsolution{\intsect}
\pgfgetlastxy{\intsectx}{\intsecty}
\ifknot@draftmode
\node[circle,fill=white,fill opacity=.5] at (\intsectx,\intsecty) {\knot@sta-\knot@stb-\intsect};
\else
\@ifundefined{knot@crossing@\knot@sta-\knot@stb-\intsect}{
%\message{\knot@sta-\knot@stb-\intsect not defined}
}{
\pgfmathtruncatemacro{\knot@under}{\csname knot@crossing@\knot@sta-\knot@stb-\intsect\endcsname == \knot@sta ? \knot@stb : \knot@sta}
\expandafter\let\expandafter\knot@over\csname knot@crossing@\knot@sta-\knot@stb-\intsect\endcsname
\pgfscope
\clip (\intsectx,\intsecty) circle[radius=10pt];
\expandafter\expandafter\expandafter\draw\expandafter\expandafter\expandafter[\csname knot@string@opts@\knot@under\endcsname,use knot path=\csname knot@string@\knot@under\endcsname] (0,0);
\expandafter\expandafter\expandafter\draw\expandafter\expandafter\expandafter[\csname knot@string@opts@\knot@over\endcsname,use knot path=\csname knot@string@\knot@over\endcsname,white,line width=3\pgflinewidth] (0,0);
\expandafter\expandafter\expandafter\draw\expandafter\expandafter\expandafter[\csname knot@string@opts@\knot@over\endcsname,use knot path=\csname knot@string@\knot@over\endcsname] (0,0);
\endpgfscope
}
\fi
}
}
}
}
\newcommand{\strand}[1][]{%
\stepcounter{knot@strings}%
\expandafter\def\csname knot@string@opts@\the\value{knot@strings}\endcsname{#1}%
\path[save knot path=\csname knot@string@\the\value{knot@strings}\endcsname]}
\newcommand{\crossing}[2]{%
\expandafter\def\csname knot@crossing@#1\endcsname{#2}}
\makeatother
\begin{document}
\begin{tikzpicture}
\begin{knot}[knot/draft mode]
\strand[red,ultra thick] (0,0) .. controls +(1,0) and +(-1,0) .. ++(2,-1) .. controls +(1,0) and +(-1,0) .. ++(2,1) .. controls +(1,0) and +(-1,0) .. ++(2,-1) .. controls +(1,0) and +(-1,0) .. ++(2,1);
\strand[blue,ultra thick] (0,-1) .. controls +(1,0) and +(-1,0) .. ++(2,1) .. controls +(1,0) and +(-1,0) .. ++(2,-1) .. controls +(1,0) and +(-1,0) .. ++(2,1) .. controls +(1,0) and +(-1,0) .. ++(2,-1);
\crossing{1-2-1}{1}
\crossing{1-2-2}{2}
\crossing{1-2-3}{1}
\crossing{1-2-4}{2}
\end{knot}
\end{tikzpicture}
\begin{tikzpicture}
\begin{knot}
\strand[red,ultra thick] (0,0) .. controls +(1,0) and +(-1,0) .. ++(2,-1) .. controls +(1,0) and +(-1,0) .. ++(2,1) .. controls +(1,0) and +(-1,0) .. ++(2,-1) .. controls +(1,0) and +(-1,0) .. ++(2,1);
\strand[blue,ultra thick] (0,-1) .. controls +(1,0) and +(-1,0) .. ++(2,1) .. controls +(1,0) and +(-1,0) .. ++(2,-1) .. controls +(1,0) and +(-1,0) .. ++(2,1) .. controls +(1,0) and +(-1,0) .. ++(2,-1);
\crossing{1-2-1}{1}
\crossing{1-2-2}{2}
\crossing{1-2-3}{1}
\crossing{1-2-4}{2}
\end{knot}
\end{tikzpicture}
\end{document}
Result (draft version on top):
Hopefully the syntax is obvious enough from the example. (It looks a lot nicer in the original PDF; the conversion to PNG is awful!). There are lots of places for improvement, but I thought I'd see if this was on the right track before polishing it.
Best Answer
When you load TikZ it loads many many macros but this is not slowing down anything per se at this time of history. It is actually not that important to load all the macros. But at the same time every library implements many TeX
ifs,dimens andlengths etc. that might run out if other packages are using lots of registers. This is usually solved (or hoped to be solved) by also loading theetexpackage which boosts the number of registers.Also some of the libraries change the behavior of options such as
positioningswitches thebelow of=tobelow= of,backgroundsswitches layering which might interfere with some patterns etc.So as a very good design decision, you turn on the rockets whenever you need them.
A nice answer by Heiko is good to keep in mind Is it possible to load a TikZ library locally?