\section{Work organization} % (fold)
\label{sec:work_organization}

Here's a sample organization. 

The line |% !TEX TS-program = lualatex| ensures that you compile with Lua\LATEX{}. The \code{standalone} class is useful, as all you need to do here is create a figure.

You can load \tkzname{tkz-euclide} in three different ways. The simplest is |\usepackage[mini]{tkz-euclide}| and you have full access to the package. You also have the option to use the \ItkzPopt{tkz-euclide}{lua} option. This will allow you, if you want to perform calculations outside of \tkzname{\tkznameofpack}, to obtain them using \code{lua}. Finally, the recommended method is to use the \ItkzPopt{tkz-euclide}{mini} option. This allows you to load only the modules necessary for drawing. You can still optionally draw using \TIKZ.

The package \pkg{ifthen} is useful if you need to use some Boolean.

While it's possible  to leave the Lua code in the  macro |directlua|, externalizing this code has its advantages. 

The first advantage is that, if you use a good editor, you have a better presentation of the code. Styles differ between \code{Lua} and \LATEX{}, making the code clearer. This is how I proceeded, then reintegrated the code into the main code.

Another advantage is that you don't have to incorrectly comment the code. For Lua code, you comment lines with |--| (double minus sign), whereas for \LATEX{}, you comment with |%|.

A third advantage is that the code can be reused.



\begin{Verbatim}
% !TEX TS-program = lualatex
% Created by Alain Matthes on 2024-01-09.

\documentclass[margin = 12pt]{standalone} 
\usepackage[mini]{tkz-euclide}
\usepackage{tkz-elements,ifthen}

\begin{document}  
\directlua{
 scale = 1.25
 dofile ("sangaku.lua")
}

\begin{tikzpicture}
   \tkzGetNodes
   \tkzDrawCircle(I,F)
   \tkzFillPolygon[color = purple](A,C,D)%
   \tkzFillPolygon[color = blue!50!black](A,B,C)%
   \tkzFillCircle[color = orange](I,F)%
\end{tikzpicture}
\end{document}
\end{Verbatim}

And here is the code for the \code{Lua} part: the file |ex_sangaku.lua|

\begin{Verbatim}
z.A         = point : new ( 0,0 ) 
z.B         = point : new ( 8,0 )
L.AB        = line : new ( z.A , z.B )
S           = L.AB : square ()
_,_,z.C,z.D = get_points (S)
z.F         = S.ac : projection (z.B)
L.BF        = line : new (z.B,z.F)
T.ABC       = triangle : new ( z.A , z.B , z.C )
L.bi        = T.ABC : bisector (2)
z.c         = L.bi.pb
L.Cc        = line : new (z.C,z.c)
z.I         = intersection (L.Cc,L.BF)
\end{Verbatim}

\directlua{
 init_elements ()
 scale = 1.25
 dofile ("sangaku.lua")
}

\begin{tikzpicture}
   \tkzGetNodes
   \tkzDrawCircle(I,F)
   \tkzFillPolygon[color = purple](A,C,D)%
   \tkzFillPolygon[color = blue!50!black](A,B,C)%
   \tkzFillCircle[color = orange](I,F)%
\end{tikzpicture}

\subsection{Scale problem} % (fold)
\label{sub:scale_problem}

If necessary, it's better to perform  scaling in the \code{Lua} section. This approach tends to be more accurate.  However, there is a caveat to be aware of. I've made it a point to avoid using numerical values in my codes whenever possible. Generally, these values only appear in the definition of fixed points.
 If the \code{scale} option is used, scaling is applied when points are created. Let's imagine you want to organize your code as follows:

\begin{mybox}{}
  \begin{verbatim}
    scale = 1.5
    xB    = 8
    z.B   = point : new ( xB,0 )
  \end{verbatim}
\end{mybox}


Scaling would then be ineffective, as the numerical values are not modified, only the point coordinates. To account for scaling, use the function \Igfct{math}{value (v) }.

\begin{mybox}{}
\begin{verbatim}
  scale  = 1.5
  xB     = value (8)
  z.B    = point : new ( xB,0 )
\end{verbatim}
\end{mybox}

\subsection{Code presentation} % (fold)
\label{sub:code_presentation}

The key point is that, unlike \LATEX{} or \TEX{}, you can insert spaces absolutely anywhere. 
% subsection code_presentation (end)
% subsection scale_problem (end)
% section work_organization (end)