Introduction

This answer provided a quick start to the kind of result you want, presenting some methods to organize your styles.

To organize our solution, let's divide it in 3 files:

1. The main mew file: mwe.tex;
2. The style file: myTikzsetStyle.sty;
3. The TikZ draw file: input_mwe_tikz.tex.

Please, save all of them in the same folder and compile the mwe.tex.

mwe.tex

The main file is simple, it calls the package tikz and its libraries; our own style file, and the chemfig package.

You may find more suitable packages for your chemicals, or draw them in another software and insert them as figures.

To make the insertion of the chemical figure more compact and easy to change in the future, I defined a command named \chemA. We just need to change its definition to change the result. This is the base concept, we will return to in the style file.

mwe.tex file

\documentclass{article} \usepackage{tikz} \usetikzlibrary{arrows} \usetikzlibrary{arrows.meta} \usetikzlibrary{calc} \usetikzlibrary{decorations} \usetikzlibrary{decorations.markings} \usetikzlibrary{shapes} \usetikzlibrary{shapes.misc} \usepackage{myTikzsetStyle} \usepackage{chemfig} \newcommand{\chemA}{ \chemfig{[:75]R-C(=[::+60]O)-[::-60]O-[::-60]C(=[::+60]O)-[::-60]R} } \begin{document} \input{input_mwe_tikz} \end{document} 

myTikzsetStyle.sty

Style files are not only useful for organizing your code or text, but also for being reusable.

The last instruction of each tikzset defines the /.default style. The idea is always to define the /.default to be able to use the style without adding parameters all the time.

The tikzsets are:

• addCross: adds an X on the figure you define for the node;
• addSum: same as addCross with a +;
• myBlock: defines the standard block, many variations are possible;
• mySimpleArrow: defines the standard arrow;
• myVecArrow: defines an arrow with different color at the edge and at the middle;
• myInnerColor: useful for keeping internal color of myVecArrow consistent under connections;
• myVecArrowColor: special case from myVecArrow to be used in special connections;
• myInnerNonWhite: used together with myVecArrowColor for connections;
• figNode: defines a way to insert external figures.

To insert the texts above, I chose to use newcommand as an alternative method to create one command for adding the texts:

• \myTextTable: the first parameter is not mandatory and it is the parameters for the scope block.

• Help about break lines in a node.

• Help about vertical alignment in a node.

myTikzsetStyle.sty file

\NeedsTeXFormat{LaTeX2e}[1994/06/01] \ProvidesPackage{myTikzStyle}[2023-12-03 Custom Package to draw my own styles with TikZ] \tikzset{addCross/.style n args={6}{ minimum size={#5 mm}, %minimum height=10mm, path picture={ \draw[#6] (path picture bounding box.south east) -- (path picture bounding box.north west) (path picture bounding box.south west) -- (path picture bounding box.north east); \node at ($(path picture bounding box.south)!0.4!(path picture bounding box.center)$) {#1}; \node at ($(path picture bounding box.west)!0.4!(path picture bounding box.center)$) {#2}; \node at ($(path picture bounding box.north)!0.4!(path picture bounding box.center)$) {#3}; \node at ($(path picture bounding box.east)!0.4!(path picture bounding box.center)$) {#4}; } }, addCross/.default={}{}{}{}{10}{} } \tikzset{addSum/.style n args={6}{ minimum size={#5 mm}, %minimum height=10mm, path picture={ \draw[#6] (path picture bounding box.south) -- (path picture bounding box.north) (path picture bounding box.west) -- (path picture bounding box.east); \node at ($(path picture bounding box.south west)!0.6!(path picture bounding box.center)$) {#1}; \node at ($(path picture bounding box.south east)!0.6!(path picture bounding box.center)$) {#2}; \node at ($(path picture bounding box.north west)!0.6!(path picture bounding box.center)$) {#3}; \node at ($(path picture bounding box.north east)!0.6!(path picture bounding box.center)$) {#4}; } }, addSum/.default={}{}{}{}{10}{black} } \tikzset{myBlock/.style n args={2}{ every node/.style={rectangle,draw, text=black, minimum width=#1, minimum height=#2,} }, myBlock/.default={1cm}{1cm} } \tikzset{mySimpleArrow/.style n args={2}{ >={latex[#1]}, every path/.style={draw=#2} }, mySimpleArrow/.default={black}{black} } \tikzset{myVecArrow/.style n args={4}{ thick, #1, decoration={markings, mark=at position 1 with {\arrow[semithick, #2]{triangle 60[fill=#3]}}}, % open triangle double distance=1.4pt, shorten >= 5.5pt, preaction = {decorate}, postaction = {draw,line width=1.4pt, #4, shorten >= 4.5pt} }, myVecArrow/.default={black}{black}{white}{white} } \tikzset{myInnerColor/.style={ semithick, #1, line width=1.4pt, shorten >= 4.5pt }, myInnerColor/.default={white} } \tikzset{myVecArrowColor/.style={ myVecArrow={red}{blue}{orange}{green}} } \tikzset{myInnerNonWhite/.style={ myInnerColor={cyan}} } \tikzset{figNode/.style={ path picture={ \node at (path picture bounding box.center) {#1};}} } \newcommand{\myTextTable}[5][]{ \begin{scope}[#1] \node[rectangle, fill=#2, text=#3, text centered, minimum width=80, minimum height=10] at (0,0.5) { \begin{tabular}{c} \textbf{#4} \end{tabular} }; \node[minimum width=20, minimum height=10, align=left, text width = 0.25\textwidth, anchor=north] at (0,0) { {#5} }; \end{scope} } 

input_mwe_tikz.tex

The key idea is always to define the largest set of common features possible, it means, use the environment scope with parameters.

At the first block, there are some red dashed rectangles, one of the filled with green.

The second block are the circle nodes applying purple. Here I added the addCross and addSum from the own style. Notice where it became purple and where it didn't.

The third block is the set of nodes using the style myBlock. This is normally the first block to draw and to define the position of its elements. Here I inserted two nodes using figNode and another node with the chemical.

The fourth block contains the basic set of mySimpleArrow, followed by the fifth block in the foreach loop to insert the myVecArrow, this is a special arrow with a colored space in the middle.

In the sequence there is a myVecArrow with parameters followed by a foreach with myVecArrowColor and myInnerNonWhite. Notice how the arrows combine nicely at the bifurcation. Just ignore the unusual color scheme.

Finally, the last block are the text above using \myTextTable. As we would use the same style more than once, we defined a command able to change some features without repeating the whole code over and over. If any change is necessary, we just do them at the command definition.

input_mwe_tikz.tex file

\begin{tikzpicture}[very thick] \begin{scope}[dashed, red] \draw (-3,-2.25) rectangle ++(5,3.25); \draw[fill opacity=0.4,fill=green!50] (-4.5,2.25) rectangle ++(8,3.5); \end{scope} \begin{scope}[purple] \node[circle,draw,addCross={$+$}{$+$}{}{}{10}{black}] (N1) at (-2,0) {}; \node[addSum] (N2) at (5,0) {}; \node[circle,draw,addSum={1}{2}{3}{4}{10}{blue}] (N3) at (5,-2) {}; \end{scope} \begin{scope}[myBlock] \node (A) at (0,-1.5) {A}; \node (B) at (-4,0) {B}; \node[figNode={\includegraphics[width=1cm]{example-image-c}}] (C) at (3,0) {}; \node[figNode={\includegraphics[width=1cm]{example-image-duck}}] (D) at (-3,4) {}; \node (chemA) at (0.5,4) {\chemA}; \node (I) at (0,0) {$\displaystyle \int$}; \end{scope} \begin{scope}[mySimpleArrow] \path[->] ($(B)+(-1.5,0)$) node[above]{$u$} -- (B); \path[->] (B) -- (N1); \path[->] (N1) -- (I) node[midway, above] {$\dot{x}$}; \path[->] (I) -- ++(1.5,0) coordinate(x) node[above]{$x$} -- (C); \path[->] (x) |- (A) -| (N1); \path[->] (C) |- (N3) node[below,midway]{$\hat{z}$}; \path[->] (N3) -- ++(1.5,0) node[above]{$z$}; \end{scope} \foreach \f in {myVecArrow}{ \draw[\f] (B) |- (D); \draw[\f] (C) -- (N2) node[above,midway]{$\hat{y}$}; \draw[\f] (N2) -- ++(1.5,0) node[above]{$y$}; }; \draw[myVecArrow={cyan}{red}{violet}{violet}] (D) -- (chemA); \foreach \f in {myVecArrowColor,myInnerNonWhite}{ \draw[\f] (chemA) -| (C); \draw[\f] (chemA) -| (N2); }; \begin{scope}[shift={(-3,8)}] \myTextTable{blue}{white}{\Large{Title A}}{Text 1.} \myTextTable[shift={(3,0)}]{blue}{white}{\Large{Title B}}{Text 2.} \myTextTable[shift={(6,0)}]{green!50!black}{white}{\Large{Title C}}{This is a very long text, yet not so long.} \end{scope} \end{tikzpicture} 

Result

The following image show our results.

How to make it, in generalized terms, which may need some finer details here and there (like opacity etc.), see the pgfmanual:

1. Separating the usual from the unusual

If you remove in your mind all those colors, rounded corners, arrow tips etc. the vast majority of components are ordinary nodes and lines, using some more colorful styles.

What is remaining then are some structures which need a little more considerations:

• the circle with a plus-sign
• the 4 vertical color-scales (min .. max etc.)
• some layered structures (green, right)
• some labels (x L etc.)
• legend (lower right)
• chem-like figures
• the 4 columns with a kind of "I'm in the background" effect

2. Possible approaches for the unusual parts

There are often more alternatives than I'm listing here. This is just to line out, how it could be achieved.

2.1 Circle+Plus

• could be a shape, i.e. a \node, with some "+" text
• could be a \pic, which just draws a circle and two axes

So \pic seems to be a structure to be used often. Think of it as a kind of macro in Tikz-terms.

2.2 Colorful scales

There's a fading-library, see the pgfmanual. Placing 0, min, max is just a \node away, and you probably will introduce 3-4 \pics or just one or two using arguments.

2.3 Layered structure

There's a whole chapter in the pfgmanual about how to do this.

2.4 Placing lables ...

... as \node will always work.

2.5 Legend

Could be done separately, is perhaps better addressed with the columns.

2.6 Chem-like figures

Basically these are simple objects (circles) which could be created by a few \foreach loops, which could include individual colors (see pgfmanal).

A lazy solution would create half a dozen similar \pics, with varying colors and labels inside. Sophisticared solutions may address it all in one go: @Qrrbrbirlbel will certainly have a few tricks to show here.

The ones with the orange background look very much the same, while just the contrasts seem to create a different visual perception. The smeared out ones may be approximated by some wider line width, or matched exactly by the mindmap-library. It's a matter of balancing effect vs. effort.

2.7 Column-structure

There are several options, too, like:

1. Perceive it all as one big Tikz-drawing. I.e. place \nodes for the headers, other \nodes for the text (which could and should be Latex: \node at (0,-2) {Local PE as node ...};). Probably you'd want to put those columns inside a layer, see above.

2. WHEN you can provide transparency for the Tikz-drawing in the middle, you just overlay the drawing with whatever table- or minipage-structure seems appropriate. (I never tried this, but speculate, it could be done.)