metapost
I want to label a scale based on a variable value and I wrote a metapost code like this.
$ := 1;
for i = -.3cm step .6cm until 3.6cm:
label.bot(str$,(i,-3.7cm));
$ := incr($);
endfor;
It just labels "$" instead of its value. How to output the variables value?
ConTeXt features several colour conversions, which are built into the core:
They are defined in the file
attr-col.lua.
Here I use the Lua function
hsvtorgb
to convert the HSV input to an RGB value which MetaPost understands. The
interface is not pretty, but it should get you started. Feel free to create a MetaPost definition for the conversion.
%% macros=mkvi
\starttexdefinition hsvtorgb #h #s #v
\ctxlua{context("(\letterpercent f, \letterpercent f, \letterpercent f)", attributes.colors.hsvtorgb(#h, #s, #v))}
\stoptexdefinition
\starttext
Hues
\dostepwiserecurse{0}{360}{20}{\dontleavehmode
\startMPcode
fill unitcircle scaled 1cm withcolor \hsvtorgb{\recurselevel}{.76}{.76};
\stopMPcode}
Saturation
\dorecurse{19}{\dontleavehmode
\startMPcode
fill unitcircle scaled 1cm withcolor \hsvtorgb{120}{.04*\recurselevel}{.76};
\stopMPcode}
Value
\dorecurse{19}{\dontleavehmode
\startMPcode
fill unitcircle scaled 1cm withcolor \hsvtorgb{120}{.76}{.04*\recurselevel};
\stopMPcode}
\stoptext
Integrating Metapost figures into your LaTeX environment is simple, if you can switch to lualatex instead of pdflatex. For example:
\documentclass{article}
\usepackage{stix}
\usepackage{luamplib}
\mplibtextextlabel{enable}
\begin{document}
A document using Stix for maths: $e=mc^2$.
\[
\begin{mplibcode}
beginfig(1);
z0 = 42 dir 12;
drawarrow origin -- z0 cutafter fullcircle scaled 6 shifted z0;
dotlabel.rt("$x$", z0);
endfig;
\end{mplibcode}
\]
\end{document}
Compile this with lualatex to get this:
Documentation is here, and in Section 12 of my own Drawing with Metapost document.
Actually it really isn't any more. Even on my old 2011 Mac Mini, it only takes a few seconds to compile my benchmark document with 120 pages of complex graphics in-line. See pww-2.tex in this project.
OK, my Drawing-with-Metapost document referenced above is also huge, and in that case I have a sort-of hybrid workflow.
I use lualatex to compile the main document -- and it happily includes all of my old .mps graphics with no changes.
And now I am gradually migrating my old .mp source to standalone luamplib graphics.
This is the template I use:
\documentclass[border=5mm]{standalone}
\usepackage{luamplib}
\begin{document}
\mplibtextextlabel{enable}
\begin{mplibcode}
beginfig(1);
endfig;
\end{mplibcode}
\end{document}
Except that for DwM I vary that a bit, and I have the common code for the main document in a separate local style file called dwmcommon.sty. Just before \begin{document} in the main document and in these standalone graphics I have \usepackage{dwmcommon} to load all the common definitions, so that I only have to maintain them in one place.
And of course I have to compile these updated MP files with lualatex instead of mpost. This produces .pdf output files directly instead of .mps or .eps, which saves one more process in the step.
The advantages of this hybrid approach are that:
I did see a Vi syntax file for Context that attempted to define MP ranges and TeX ranges, but it was not a great success. So what I do (in Vim) is just switch between them manually, using set ft=mp or set ft=tex as needed.
Best Answer
To get the value of the variable, use the
decimalmacro. The following works:$:=1; for i = -.3cm step .6cm until 3.6cm: label.bot(decimal $,(i,-3.7cm)); $ := incr($); endforTo quote the MetaPost manual:
further