[Tex/LaTex] Macros/encapsulation in TIKZ

tikz-pgftikz-styles

I'm considering starting to use TIKZ, and trying to figure out if it will do what I want, and how.

I have a large document with many pictures of Bezier curves. For each of these, I'd like to draw the curve itself, four dots at its control points, and three lines joining these four points. I'm currently drawing these using Powerpoint macros. They look like this:

enter image description here

I want to "encapsulate" this thing in a function or macro, to make it easy to instantiate, and ensure consistency between different pictures. I imagine that the inputs to the function would be the coordinates of the four points and three colors (one for the curve, one for the points, and one for the lines).

I read about the "tikzstyle" facility. It sounds good, because I can place the "style" definition externally, and re-use it in all my pictures, which gives me consistency and easy global changes. But I'm not sure how the "input arguments" (the coordinates) would work.

Is tikzstyle the right approach, or is there some better way (either using TIKZ or some other similar tool)?

Best Answer

This is one possible solution. Here a macro called mybezier is defined within a tikzpicture environment as displayed below that takes 4 arguments: P_0, P_a, P_b, P_1. Then call \mybezier{p0}{pa}{pb}{p1} to draw.

\newcommand\mybezier[4]{
    \begin{tikzpicture}
    \draw [green]          (#1)--(#2)-- (#3)--(#4);
    \draw[very thick,blue] (#1).. controls (#2) and (#3) .. (#4);
    \draw [fill=red,draw=black]    (#1)node[left] {$P_0$} circle (2pt);
    \draw [fill=red,draw=black]    (#2)node[left] {$P_a$} circle (2pt);
    \draw [fill=red,draw=black]    (#3)node[right]{$P_b$} circle (2pt);
    \draw [fill=red,draw=black]    (#4)node[right]{$P_1$} circle (2pt);
    \end{tikzpicture}
}

enter image description here

Code

\documentclass[]{article}
\usepackage{tikz}
\usetikzlibrary{positioning}
\newcommand\mybezier[4]{
    \begin{tikzpicture}
    \draw [green]          (#1)--(#2)-- (#3)--(#4);
    \draw[very thick,blue] (#1).. controls (#2) and (#3) .. (#4);
    \draw [fill=red,draw=black]    (#1)node[left] {$P_0$} circle (2pt);
    \draw [fill=red,draw=black]    (#2)node[left] {$P_a$} circle (2pt);
    \draw [fill=red,draw=black]    (#3)node[right]{$P_b$} circle (2pt);
    \draw [fill=red,draw=black]    (#4)node[right]{$P_1$} circle (2pt);
    \end{tikzpicture}
}
\begin{document}
\mybezier{1,0}{2,3}{5,4}{6,1}
\end{document}

Related Solutions

[Tex/LaTex] Forcing tikz/pgf to expand macros within commands

My knowledge of TeX expansion is rather limited, but I think the problem is not with PGF but with TeX itself. It tries to expand \pgfpoincurveattime first and looks for its arguments before expanding \bcurve. Hence \bcurve is taken as one of the arguments of \pgfpointcurveattime and TeX looks for the other arguments in the text that follows.

So what you want to do, is to expand \bcurve first (once). To change the order of expansion, one uses \expandafter: \expandafter\a\b expands \b and adds the result after \a and then continues on to process \a. The problem here is that you want to skip over five tokens ({.25}), which would require a lot of \expandafters:

\expandafter\pgfpointcurveattime\expandafter{\expandafter.\expandafter2\expandafter5\expandafter}\bcurve

After the execution of the \expandafters, this will leave TeX with

\pgfpointcurveattime{.25}{\pgfpoint{0cm}{0cm}}{\pgfpoint{0cm}{1cm}}{\pgfpoint{1cm}{1cm}}{\pgfpoint{1cm}{0cm}}

One possible solution to save on typing all those \expandafters and getting more readable code is to save .25 into a macro that can be skipped over in one step:

\newcommand*\pos{.25}
\expandafter\pgfpointcurveattime\expandafter\pos\bcurve

After the execution of the \expandafters, this will leave TeX with

\pgfpointcurveattime\pos{\pgfpoint{0cm}{0cm}}{\pgfpoint{0cm}{1cm}}{\pgfpoint{1cm}{1cm}}{\pgfpoint{1cm}{0cm}}

[Tex/LaTex] Basic skills needed to draw simple functions like polynomials, trigonometry, exponential, logarithm, etc

More examples using pgfplots

enter image description here

Code

\documentclass[twocolumn]{article}
\usepackage[margin=1cm]{geometry}
\usepackage{tikz,xcolor}
\usepackage{pgfplots}
\pgfplotsset{compat=1.8}

\begin{document}

\begin{tikzpicture}
\begin{axis}[domain=-4:4,
    restrict y to domain=0:4,
    samples=100,
    grid=major,smooth,
    xlabel=$x$,
    ylabel=$y(x)$, 
    legend pos=north west]
\addplot [color=green,thick]  {exp(x)};
\addplot [color=purple,thick] {exp(-x)}; 
\legend{$e^x$, $e^{-x}$}
\end{axis}
\end{tikzpicture}

\begin{tikzpicture}
\begin{axis}[domain=0.001:6,                  
    samples=50,
    grid=major,smooth,
    xlabel=$x$,
    ylabel=$y(x)$,
    legend pos=north east]
\addplot [color=red,thick]    {1/(0.5*x*(2*pi)^0.5)*exp(-ln(x)*ln(x)/0.5)};
\legend{$ {\frac{1}{(0.5x(2\pi)^{0.5})}e^{-\frac{\ln(x)\ln(x)}{0.5}}}$}
\end{axis}
\end{tikzpicture}

\begin{tikzpicture}
\begin{axis}[                 
    samples=100,
    restrict y to domain=-4:4,
    grid=major,smooth,
    xlabel=$x$,
    ylabel=$y(x)$,
    legend pos=north east]
\addplot [color=red,thick,domain=-180:180]      {sin(x)};
\legend{$sin(x)$,$x*sin(1/x)$}
\end{axis}
\end{tikzpicture}

\begin{tikzpicture}
\begin{axis}[                 
    samples=200,
    restrict y to domain=-1:1,
    grid=major,
    xlabel=$x$,
    ylabel=$y(x)$,
    legend pos=north east]
\addplot [color=red,thick,domain=-0.02:0.02 ]     {x*sin(1/x)};
\legend{$x*sin(1/x)$}
\end{axis}
\end{tikzpicture}

\vspace{2cm}

\begin{tikzpicture}
\begin{semilogyaxis}[                
    log basis y=10,
    grid=major,smooth,
    xlabel=$x$,
    ylabel=$y(x)$,
    legend pos=north east]
\addplot [color=red,thick]  {10^x};
\legend{$10^x$}
\end{semilogyaxis}
\end{tikzpicture}

\vspace{3cm}

\begin{tikzpicture}
\begin{loglogaxis}[
grid=major,
xlabel=$x$,
ylabel=$y(x)$,
legend pos=north west
]
\addplot[only marks, mark size=4pt,mark=triangle,fill,black] coordinates{
(1 , 10)
(10 , 100)
(100 ,  1000)};
\legend{discrete type}
\end{loglogaxis}
\end{tikzpicture}

\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Forcing tikz/pgf to expand macros within commands

[Tex/LaTex] Basic skills needed to draw simple functions like polynomials, trigonometry, exponential, logarithm, etc

Related Question