initial import

+all: chap1 chap2
+
+chap1: chap1.pdf chap1-anim.gif
+
+chap2: chap2.pdf
+	python3 chap2-anim.py
+	mv chap2*.gif chap2/
+
+%.pdf: %.tex
+	latexmk -pdf $<
+	latexmk -pdf -c $<
+	mkdir -p $(*F)
+	convert -background white -alpha remove -density 600 $@ $(*F)/fig-%03d.png
+
+%.gif: %.py %.tex
+	python3 $<

+from t2g import *
+
+markings = {0: dict(a=3, b=0, c=0, d=0),
+            1: dict(a=1, b=1, c=0, d=0),
+            2: dict(a=1, b=0, c=1, d=0),
+            3: dict(a=1, b=0, c=0, d=2),
+            4: dict(a=2, b=0, c=0, d=1),
+            5: dict(a=0, b=1, c=0, d=1),
+            6: dict(a=0, b=0, c=1, d=1),
+            7: dict(a=0, b=0, c=0, d=3)}
+
+state = {"a": 0, "b": 0, "c": 0, "d": 0}
+
+trans = {(0,1): "t",
+         (1,2): "u",
+         (2,3): "v",
+         (3,4): "w",
+         (4,0): "w",
+         (4,5): "t",
+         (5,6): "u",
+         (6,7): "v",
+         (7,3): "w",
+         (6,2): "w",
+         (5,1): "w"}
+
+active = dict((t, "") for t in "tuvw")
+active.update((s, "") for s in range(8))
+active.update((f, "") for f in trans)
+
+load("chap1-anim.tex")
+src = 0
+
+for dst in [1, 2, 3, 4, 0, 1, 2, 3, 4, 5, 6, 7, 3, 4, 5, 1, 2, 3, 4, 5, 6, 2, 3, 4, 0] :
+    state = markings[src]
+    active[src] = "active"
+    frame(.8)
+    active[src,dst] = active[trans[src,dst]] = "active"
+    frame(.8)
+    active[src] = active[src,dst] = active[trans[src,dst]] = ""
+    src = dst
+
+gif("chap1-anim.gif")

+\documentclass[multi={tikzpicture},crop=true,border=5pt]{standalone}
+
+\usepackage{tikz}
+\usetikzlibrary{shapes,arrows,arrows.meta,petri}
+\tikzset{
+  >=latex,
+  every place/.style={minimum size=6mm},
+  every transition/.style={minimum size=6mm},
+  token distance=6pt,
+}
+
+\tikzstyle{trans}=[transition]
+
+\tikzstyle{state}=[draw=blue!50!gray!50!white,
+  fill=blue!70!gray!10!white,
+  line width=2pt,
+  cloud,cloud puffs=8,
+  inner sep=-1pt]
+
+\tikzstyle{fire}=[arrows={-Straight Barb[scale=.6]},
+  shorten >=-2pt, shorten <=-1pt,
+  draw=blue!50!gray!50!white,
+  line width=2pt,
+  fill opacity=0,
+  text opacity=1,
+  line cap=round,
+  rounded corners]
+
+\tikzstyle{active}=[draw=green!50!gray!50!white,
+  fill=green!70!gray!10!white]
+
+\def\matrix #1#2#3#4{%
+  $\begin{array}{c@{\hspace{5pt}}c}
+    #1 & #2 \\
+    #3 & #4
+  \end{array}$}
+
+\begin{document}
+
+%%FRAME
+
+\begin{tikzpicture}
+  \begin{scope}[yshift=45mm,xshift=28mm,scale=1.2]
+    \node[place,tokens={{ state["a"] }}] (a) at (0,0) {};
+    \node[left] at (a.west) {$a$};
+    \node[trans,{{ active["t"] }}] (t) at (1,0) {$t$};
+    \draw[->] (a) -- node[above]{2} (t);
+    \node[place,tokens={{ state["b"] }}] (b) at (2,0) {};
+    \node[right] at (b.east) {$b$};
+    \draw[->] (t) -- (b);
+    \node[trans,{{ active["u"] }}] (u) at (2,-1) {$u$};
+    \draw[->] (b) -- (u);
+    \node[place,tokens={{ state["c"] }}] (c) at (2,-2) {};
+    \node[right] at (c.east) {$c$};
+    \draw[->] (u) -- (c);
+    \node[trans,{{ active["v"] }}] (v) at (1,-2) {$v$};
+    \draw[->] (c) -- (v);
+    \node[place,tokens={{ state["d"] }}] (d) at (0,-2) {};
+    \node[left] at (d.west) {$d$};
+    \draw[->] (v) -- node[above]{2} (d);
+    \node[trans,{{ active["w"] }}] (w) at (0,-1) {$w$};
+    \draw[->] (d) -- (w);
+    \draw[->] (w) -- (a);
+  \end{scope}
+  \begin{scope}[scale=2]
+    \node[state,{{ active[0] }}] (0) at (0,0) {\matrix 3000};
+    \node[state,{{ active[1] }}] (1) at (1,0) {\matrix 1100};
+    \draw[fire,{{ active[0,1] }}] (0) -- node[above] {$t$} (1);
+    \node[state,{{ active[2] }}] (2) at (2,0) {\matrix 1001};
+    \draw[fire,{{ active[1,2] }}] (1) -- node[above] {$u$} (2);
+    \node[state,{{ active[3] }}] (3) at (3,0) {\matrix 1020};
+    \draw[fire,{{ active[2,3] }}] (2) -- node[above] {$v$} (3);
+    \node[state,{{ active[4] }}] (4) at (4,0) {\matrix 2010};
+    \draw[fire,{{ active[3,4] }}] (3) -- node[above] {$w$} (4);
+    \draw[fire,{{ active[4,0] }}] (4) |- node[near end,above] {$w$} +(-1,.5) -| (0);
+    \node[state,{{ active[5] }}] (5) at (1,-1) {\matrix 0110};
+    \draw[fire,{{ active[4,5] }}] (4) |- node[pos=.05,right] {$t$} +(-1,-1.5) -| (5);
+    \draw[fire,{{ active[5,1] }}] (5) -- node[left] {$w$} (1);
+    \node[state,{{ active[6] }}] (6) at (2,-1) {\matrix 0011};
+    \draw[fire,{{ active[5,6] }}] (5) -- node[above] {$u$} (6);
+    \draw[fire,{{ active[6,2] }}] (6) -- node[left] {$w$} (2);
+    \node[state,{{ active[7] }}] (7) at (3,-1) {\matrix 0030};
+    \draw[fire,{{ active[7,3] }}] (7) -- node[left] {$w$} (3);
+    \draw[fire,{{ active[6,7] }}] (6) -- node[above] {$v$} (7);
+  \end{scope}
+\end{tikzpicture}
+
+%%/FRAME
+
+\end{document}

+\documentclass[multi={tikzpicture},crop=true,border=5pt]{standalone}
+
+\usepackage{tikz}
+\usetikzlibrary{shapes,arrows,arrows.meta,petri}
+\tikzset{
+  >=latex,
+  every place/.style={minimum size=6mm},
+  every transition/.style={minimum size=6mm},
+  token distance=6pt,
+}
+
+\tikzstyle{trans}=[transition]
+
+\tikzstyle{state}=[draw=blue!50!gray!50!white,
+  fill=blue!70!gray!10!white,
+  line width=2pt,
+  cloud,cloud puffs=8,
+  inner sep=-1pt]
+
+\tikzstyle{fire}=[arrows={-Straight Barb[scale=.6]},
+  shorten >=-2pt, shorten <=-1pt,
+  draw=blue!50!gray!50!white,
+  line width=2pt,
+  line cap=round,
+  rounded corners]
+
+\def\matrix #1#2#3#4{%
+  $\begin{array}{c@{\hspace{5pt}}c}
+    #1 & #2 \\
+    #3 & #4
+  \end{array}$}
+
+\begin{document}
+
+% Les réseaux de Petri
+
+% Chapitre 1. Quoi ?
+% Où l'on apprend ce que sont les réseaux de Petri.
+
+%%%
+
+% Ceci est une place.
+
+\begin{tikzpicture}
+  \node[place] (p) at (0,0) {};
+\end{tikzpicture}
+
+% Une place peut contenir des jetons (ici 3).
+
+\begin{tikzpicture}
+  \node[place,tokens=3] (p) at (0,0) {};
+\end{tikzpicture}
+
+% Ceci est une transition.
+
+% Une transition ne peut pas contenir de jetons, non non.
+
+\begin{tikzpicture}
+  \node[trans] (t) at (0,0) {};
+\end{tikzpicture}
+
+% Ceci est un arc.
+
+\begin{tikzpicture}
+  \draw[->] (0,0) -- (1,0);
+\end{tikzpicture}
+
+% Un arc peut être décoré par un nombre entier (valant au moins 1).
+
+% Quand on ne met pas de nombre, c'est qu'il vaut 1.
+
+\begin{tikzpicture}
+  \draw[->] (0,0) -- node[above]{2} (1,0);
+\end{tikzpicture}
+
+% Un arc relie une place à une transition, ou l'inverse.
+
+\begin{tikzpicture}[xscale=1.2]
+  \node[place,tokens=3] (p) at (0,0) {};
+  \node[trans] (t) at (1,0) {};
+  \draw[->] (p) -- node[above]{2} (t);
+  \node[trans] (u) at (0,-1) {};
+  \node[place] (q) at (1,-1) {};
+  \draw[->] (u) -- (q);
+\end{tikzpicture}
+
+% Mais un arc ne relie jamais deux places ou deux transitions.
+% Jamais, jamais.
+
+\begin{tikzpicture}[xscale=1.2]
+  \node[place,tokens=3] (p) at (0,0) {};
+  \node[place] (q) at (1,0) {};
+  \draw[->] (p) -- node[above]{2} (q);
+  \node[trans] (t) at (0,-1) {};
+  \node[trans] (u) at (1,-1) {};
+  \draw[->] (t) -- (u);
+  \node[forbidden sign,line width=5pt,draw=red,inner sep=6mm] at (.5,-.5) {};
+\end{tikzpicture}
+
+% Ceci est un réseau de Petri que nous appellerons Carl.
+
+% Carl a une transition, deux places (l'une a trois jetons, l'autre
+% zéro), et deux arcs.
+
+\begin{tikzpicture}[xscale=1.2]
+  \node[place,tokens=3] (p) at (0,0) {};
+  \node[trans] (t) at (1,0) {};
+  \draw[->] (p) -- node[above]{2} (t);
+  \node[place] (q) at (2,0) {};
+  \draw[->] (t) -- (q);
+\end{tikzpicture}
+
+% Les transitions consomment et produisent des jetons dans les places,
+% selon ce qu'indiquent les arcs.
+
+% La transition de Carl peut consommer deux jetons dans la place de
+% gauche et en produire un dans celle de droite (le 1 n'est pas
+% indiqué puisque c'est 1 justement).
+
+% Si elle le fait, on dit qu'on tire la transition.
+
+%%%
+
+% Ici, Carl a tiré sa transition. Deux jetons ont disparu de la place
+% de gauche, et un a été ajouté dans celle de droite. Comme indiqué
+% par les arcs.
+
+\begin{tikzpicture}[xscale=1.2]
+  \node[place,tokens=1] (p) at (0,0) {};
+  \node[trans] (t) at (1,0) {};
+  \draw[->] (p) -- node[above]{2} (t);
+  \node[place,tokens=1] (q) at (2,0) {};
+  \draw[->] (t) -- (q);
+\end{tikzpicture}
+
+% Maintenant, Carl ne peut plus tirer sa transition, car elle ne peut
+% pas consommer deux jetons dans la place de gauche qui n'en contient
+% qu'un. Donc Carl est bloqué. (Pauvre Carl.)
+
+%%%
+
+% Voici un autre réseau de Petri, appelons le Adam. Comme il a
+% beaucoup de places et de transitions, on leur donne des noms: a, b,
+% c, d pour les places, et t, u, v, w pour les transitions.
+
+\begin{tikzpicture}[scale=1.2]
+  \node[place,tokens=3] (a) at (0,0) {};
+  \node[left] at (a.west) {$a$};
+  \node[trans] (t) at (1,0) {$t$};
+  \draw[->] (a) -- node[above]{2} (t);
+  \node[place] (b) at (2,0) {};
+  \node[right] at (b.east) {$b$};
+  \draw[->] (t) -- (b);
+  \node[trans] (u) at (2,-1) {$u$};
+  \draw[->] (b) -- (u);
+  \node[place] (c) at (2,-2) {};
+  \node[right] at (c.east) {$c$};
+  \draw[->] (u) -- (c);
+  \node[trans] (v) at (1,-2) {$v$};
+  \draw[->] (c) -- (v);
+  \node[place] (d) at (0,-2) {};
+  \node[left] at (d.west) {$d$};
+  \draw[->] (v) -- node[above]{2} (d);
+  \node[trans] (w) at (0,-1) {$w$};
+  \draw[->] (d) -- (w);
+  \draw[->] (w) -- (a);
+\end{tikzpicture}
+
+% Adam a trois jetons dans sa place a, et aucun ailleurs. On appelle
+% ça son marquage, c'est-à-dire le nombre de jetons dans chaque place.
+
+% On peut le dessiner dans un petit nuage bleu.
+
+\begin{tikzpicture}[scale=1.2]
+  \node[state] (s) at (1,-1) {\matrix 3000};
+  \node[place,tokens=3] (a) at (0,0) {};
+  \node[left] at (a.west) {$a$};
+  \node[trans] (t) at (1,0) {$t$};
+  \draw[->] (a) -- node[above]{2} (t);
+  \node[place] (b) at (2,0) {};
+  \node[right] at (b.east) {$b$};
+  \draw[->] (t) -- (b);
+  \node[trans] (u) at (2,-1) {$u$};
+  \draw[->] (b) -- (u);
+  \node[place] (c) at (2,-2) {};
+  \node[right] at (c.east) {$c$};
+  \draw[->] (u) -- (c);
+  \node[trans] (v) at (1,-2) {$v$};
+  \draw[->] (c) -- (v);
+  \node[place] (d) at (0,-2) {};
+  \node[left] at (d.west) {$d$};
+  \draw[->] (v) -- node[above]{2} (d);
+  \node[trans] (w) at (0,-1) {$w$};
+  \draw[->] (d) -- (w);
+  \draw[->] (w) -- (a);
+  \draw[|->,yellow,very thick,shorten >=-10pt] (a) -- (s.north west);
+  \draw[|->,yellow,very thick,shorten >=-10pt] (b) -- (s.north east);
+  \draw[|->,yellow,very thick,shorten >=-10pt] (c) -- (s.south east);
+  \draw[|->,yellow,very thick,shorten >=-10pt] (d) -- (s.south west);
+\end{tikzpicture}
+
+% Adam peut tirer sa transition t, ce qui enlèvera deux jetons dans a
+% et en ajoutera un dans b. On obtient alors ce marquage.
+
+\begin{tikzpicture}
+  \node[state] {\matrix 1100};
+\end{tikzpicture}
+
+% On peut représenter cette évolution entre deux marquages par un
+% graphe.
+
+\begin{tikzpicture}[scale=2]
+  \node[state] (0) at (0,0) {\matrix 3000};
+  \node[state] (1) at (1,0) {\matrix 1100};
+  \draw[fire] (0) -- node[above] {$t$} (1);
+\end{tikzpicture}
+
+% Et on peut prolonger ce graphe en tirant u, v, puis w.
+
+\begin{tikzpicture}[scale=2]
+  \node[state] (0) at (0,0) {\matrix 3000};
+  \node[state] (1) at (1,0) {\matrix 1100};
+  \draw[fire] (0) -- node[above] {$t$} (1);
+  \node[state] (2) at (2,0) {\matrix 1001};
+  \draw[fire] (1) -- node[above] {$u$} (2);
+  \node[state] (3) at (3,0) {\matrix 1020};
+  \draw[fire] (2) -- node[above] {$v$} (3);
+  \node[state] (4) at (4,0) {\matrix 2010};
+  \draw[fire] (3) -- node[above] {$w$} (4);
+\end{tikzpicture}
+
+% À partir du dernier marquage atteint, on peut encore tirer w, et on
+% retrouve alors le marquage départ.
+
+\begin{tikzpicture}[scale=2]
+  \node[state] (0) at (0,0) {\matrix 3000};
+  \node[state] (1) at (1,0) {\matrix 1100};
+  \draw[fire] (0) -- node[above] {$t$} (1);
+  \node[state] (2) at (2,0) {\matrix 1001};
+  \draw[fire] (1) -- node[above] {$u$} (2);
+  \node[state] (3) at (3,0) {\matrix 1020};
+  \draw[fire] (2) -- node[above] {$v$} (3);
+  \node[state] (4) at (4,0) {\matrix 2010};
+  \draw[fire] (3) -- node[above] {$w$} (4);
+  \draw[fire] (4) |- node[near end,above] {$w$} +(-1,.5) -| (0);
+\end{tikzpicture}
+
+% Mais, hop hop hop, pas si vite... Au lieu de tirer w, on aurait
+% aussi pu tirer t puisqu'il y a deux jetons dans a. Du coup, on
+% obtient un branchement dans notre graphe.
+
+\begin{tikzpicture}[scale=2]
+  \node[state] (0) at (0,0) {\matrix 3000};
+  \node[state] (1) at (1,0) {\matrix 1100};
+  \draw[fire] (0) -- node[above] {$t$} (1);
+  \node[state] (2) at (2,0) {\matrix 1001};
+  \draw[fire] (1) -- node[above] {$u$} (2);
+  \node[state] (3) at (3,0) {\matrix 1020};
+  \draw[fire] (2) -- node[above] {$v$} (3);
+  \node[state] (4) at (4,0) {\matrix 2010};
+  \draw[fire] (3) -- node[above] {$w$} (4);
+  \draw[fire] (4) |- node[near end,above] {$w$} +(-1,.5) -| (0);
+  \node[state] (5) at (1,-1) {\matrix 0110};
+  \draw[fire] (4) |- node[pos=.05,right] {$t$} +(-1,-1.5) -| (5);
+\end{tikzpicture}
+
+% On continue : à partir de chaque marquage, on tire toutes les
+% transitions possibles. Et on obtient ce qu'on appelle le graphe de
+% marquages.
+
+\begin{tikzpicture}[scale=2]
+  \node[state] (0) at (0,0) {\matrix 3000};
+  \node[state] (1) at (1,0) {\matrix 1100};
+  \draw[fire] (0) -- node[above] {$t$} (1);
+  \node[state] (2) at (2,0) {\matrix 1001};
+  \draw[fire] (1) -- node[above] {$u$} (2);
+  \node[state] (3) at (3,0) {\matrix 1020};
+  \draw[fire] (2) -- node[above] {$v$} (3);
+  \node[state] (4) at (4,0) {\matrix 2010};
+  \draw[fire] (3) -- node[above] {$w$} (4);
+  \draw[fire] (4) |- node[near end,above] {$w$} +(-1,.5) -| (0);
+  \node[state] (5) at (1,-1) {\matrix 0110};
+  \draw[fire] (4) |- node[pos=.05,right] {$t$} +(-1,-1.5) -| (5);
+  \draw[fire] (5) -- node[left] {$w$} (1);
+  \node[state] (6) at (2,-1) {\matrix 0011};
+  \draw[fire] (5) -- node[above] {$u$} (6);
+  \draw[fire] (6) -- node[left] {$w$} (2);
+  \node[state] (7) at (3,-1) {\matrix 0030};
+  \draw[fire] (7) -- node[left] {$w$} (3);
+  \draw[fire] (6) -- node[above] {$v$} (7);
+\end{tikzpicture}
+
+% Revoyons cette action au ralenti...
+
+% On remarque qu'Adam, contrairement à Carl, n'a aucun blocage.
+% (C'est un réseau épanoui.)
+
+%%%
+
+% Notre chapitre 1 est maintenant terminé.
+
+% À bientôt pour le chapitre 2: pourquoi ?
+
+\end{document}

+from t2g import *
+
+#######################
+
+load("chap2-gates.tex")
+
+state = {"low": 0, "high": 1}
+active = {"down": "", "up": ""}
+
+frame(.8)
+active["down"] = "active"
+frame(.8)
+active["down"] = ""
+state = {"low": 1, "high": 0}
+frame(.8)
+active["up"] = "active"
+frame(.8)
+
+gif("chap2-gates.gif")
+
+#######################
+
+load("chap2-track.tex")
+
+state = {"far": 1, "before": 0, "inside": 0}
+active = {"enter": "", "exit": "", "approach": ""}
+
+frame(.8)
+active["approach"] = "active"
+frame(.8)
+active["approach"] = ""
+state = {"far": 0, "before": 1, "inside": 0}
+frame(.8)
+active["enter"] = "active"
+frame(.8)
+active["enter"] = ""
+state = {"far": 0, "before": 0, "inside": 1}
+frame(.8)
+active["exit"] = "active"
+frame(.8)
+
+gif("chap2-track.gif")
+
+#######################
+
+load("chap2-draft.tex")
+
+state = {"far": 1, "before": 0, "inside": 0, "low": 0, "high": 1, "godown": 0, "goup": 0}
+active = {"enter": "", "exit": "", "approach": "", "down": "", "up": ""}
+
+frame(.8)
+active["approach"] = "active"
+frame(.8)
+active["approach"] = ""
+state = {"far": 0, "before": 1, "inside": 0, "low": 0, "high": 1, "godown": 1, "goup": 0}
+frame(.8)
+active["down"] = "active"
+frame(.8)
+active["down"] = ""
+state = {"far": 0, "before": 1, "inside": 0, "low": 1, "high": 0, "godown": 0, "goup": 0}
+frame(.8)
+active["enter"] = "active"
+frame(.8)
+active["enter"] = ""
+state = {"far": 0, "before": 0, "inside": 1, "low": 1, "high": 0, "godown": 0, "goup": 0}
+frame(.8)
+active["exit"] = "active"
+frame(.8)
+active["exit"] = ""
+state = {"far": 1, "before": 0, "inside": 0, "low": 1, "high": 0, "godown": 0, "goup": 1}
+frame(.8)
+active["up"] = "active"
+frame(.8)
+
+gif("chap2-draft.gif")
+
+#######################
+
+load("chap2-test.tex")
+
+state = {"far": 1, "before": 0, "inside": 0, "low": 0, "high": 1, "godown": 0, "goup": 0}
+active = {"enter": "", "exit": "", "approach": "", "down": "", "up": "",
+          0: "active"}
+active.update((s, "") for s in range(1,5))
+
+frame(.8)
+active["approach"] = "active"
+frame(.8)
+active["approach"] = active[0] = ""
+active[1] = "active"
+state = {"far": 0, "before": 1, "inside": 0, "low": 0, "high": 1, "godown": 1, "goup": 0}
+frame(.8)
+active["down"] = "active"
+frame(.8)
+active["down"] = active[1] = ""
+active[2] = "active"
+state = {"far": 0, "before": 1, "inside": 0, "low": 1, "high": 0, "godown": 0, "goup": 0}
+frame(.8)
+active["enter"] = "active"
+frame(.8)
+active["enter"] = active[2] = ""
+active[3] = "active"
+state = {"far": 0, "before": 0, "inside": 1, "low": 1, "high": 0, "godown": 0, "goup": 0}
+frame(.8)
+active["exit"] = "active"
+frame(.8)
+active["exit"] = active[3] = ""
+active[4] = "active"
+state = {"far": 1, "before": 0, "inside": 0, "low": 1, "high": 0, "godown": 0, "goup": 1}
+frame(.8)
+active["up"] = "active"
+frame(.8)
+
+gif("chap2-test.gif", dpi=450)

+\documentclass[multi={tikzpicture},crop=true,border=5pt]{standalone}
+
+\usepackage[utf8]{inputenc}
+
+\usepackage{verbatim}
+\usepackage{tikz}
+\usetikzlibrary{shapes,arrows,arrows.meta,petri}
+\tikzset{
+  >=latex,
+  every place/.style={minimum size=6mm},
+  every transition/.style={minimum size=6mm},
+  token distance=6pt,
+}
+
+\tikzstyle{trans}=[transition]
+
+\tikzstyle{arc}=[->,rounded corners]
+
+\tikzstyle{state}=[draw=blue!50!gray!50!white,
+  fill=blue!70!gray!10!white,
+  line width=2pt,
+  cloud,cloud puffs=8,
+  inner sep=-1pt]
+
+\tikzstyle{fire}=[arrows={-Straight Barb[scale=.6]},
+  shorten >=-2pt, shorten <=-1pt,
+  draw=blue!50!gray!50!white,
+  line width=2pt,
+  line cap=round,
+  rounded corners]
+
+\tikzstyle{active}=[draw=green!50!gray!50!white,
+  fill=green!70!gray!10!white]
+
+\begin{document}
+
+%%FRAME
+
+\begin{tikzpicture}[scale=1.2]
+  \node[trans,{{ active["approach"] }}] (approach) at (0,0) {};
+  \node[rotate=45] at (approach) {\tiny\textsf{approche}};
+  \node[place,tokens={{ state["before"] }}] (before) at (1,0) {};
+  \node[below] at (before.south) {\tiny\textsf{avant}};
+  \node[trans,{{ active["enter"] }}] (enter) at (2,0) {};
+  \node[rotate=45] at (enter) {\tiny\textsf{entre}};
+  \node[place,tokens={{ state["inside"] }}] (inside) at (3,0) {};
+  \node[below] at (inside.south) {\tiny\textsf{dedans}};
+  \node[trans,{{ active["exit"] }}] (exit) at (4,0) {};
+  \node[rotate=45] at (exit) {\tiny\textsf{sort}};
+  \node[place,tokens={{ state["far"] }}] (far) at (2,-1) {};
+  \node[below] at (far.south) {\tiny\textsf{loin}};
+  \draw[arc] (before) -- (enter);
+  \draw[arc] (enter) -- (inside);
+  \draw[arc] (inside) -- (exit);
+  \draw[arc] (exit) |- (far);
+  \draw[arc] (far) -| (approach);
+  \draw[arc] (approach) -- (before);
+  %
+  \node[place,tokens={{ state["low"] }}] (low) at (2,1) {};
+  \node[below] at (low.south) {\tiny\textsf{bas}};
+  \node[place,tokens={{ state["high"] }}] (high) at (2,3) {};
+  \node[above] at (high.north) {\tiny\textsf{haut}};
+  \node[trans,{{ active["down"] }}] (down) at (1,2) {};
+  \node[rotate=45] at (down) {\tiny\textsf{baisse}};
+  \node[trans,{{ active["up"] }}] (up) at (3,2) {};
+  \node[rotate=45] at (up) {\tiny\textsf{lève}};
+  \draw[arc] (high) -| (down);
+  \draw[arc] (down) |- (low);
+  \draw[arc] (low) -| (up);
+  \draw[arc] (up) |- (high);
+  %
+  \node[place,tokens={{ state["godown"] }}] (godown) at (0,2) {};
+  \node[above] at (godown.north) {\tiny\textsf{descendre}};
+  \draw[arc] (approach) -- (godown);
+  \draw[arc] (godown) -- (down);
+  \node[place,tokens={{ state["goup"] }}] (goup) at (4,2) {};
+  \node[above] at (goup.north) {\tiny\textsf{relever}};
+  \draw[arc] (exit) -- (goup);
+  \draw[arc] (goup) -- (up);
+\end{tikzpicture}
+
+%%/FRAME
+
+\end{document}

+\documentclass[multi={tikzpicture},crop=true,border=5pt]{standalone}
+
+\usepackage[utf8]{inputenc}
+
+\usepackage{verbatim}
+\usepackage{tikz}
+\usetikzlibrary{shapes,arrows,arrows.meta,petri}
+\tikzset{
+  >=latex,
+  every place/.style={minimum size=6mm},
+  every transition/.style={minimum size=6mm},
+  token distance=6pt,
+}
+
+\tikzstyle{trans}=[transition]
+
+\tikzstyle{arc}=[->,rounded corners]
+
+\tikzstyle{state}=[draw=blue!50!gray!50!white,
+  fill=blue!70!gray!10!white,
+  line width=2pt,
+  cloud,cloud puffs=8,
+  inner sep=-1pt]
+
+\tikzstyle{fire}=[arrows={-Straight Barb[scale=.6]},
+  shorten >=-2pt, shorten <=-1pt,
+  draw=blue!50!gray!50!white,
+  line width=2pt,
+  line cap=round,
+  rounded corners]
+
+\tikzstyle{active}=[draw=green!50!gray!50!white,
+  fill=green!70!gray!10!white]
+
+\begin{document}
+
+%%FRAME
+
+\begin{tikzpicture}[scale=1.2]
+  \node[place,tokens={{ state["low"] }}] (low) at (0,0) {};
+  \node[below] at (low.south) {\tiny\textsf{bas}};
+  \node[place,tokens={{ state["high"] }}] (high) at (0,2) {};
+  \node[above] at (high.north) {\tiny\textsf{haut}};
+  \node[trans,{{ active["down"] }}] (down) at (-1,1) {};
+  \node[rotate=45] at (down) {\tiny\textsf{baisse}};
+  \node[trans,{{ active["up"] }}] (up) at (1,1) {};
+  \node[rotate=45] at (up) {\tiny\textsf{lève}};
+  \draw[arc] (high) -| (down);
+  \draw[arc] (down) |- (low);
+  \draw[arc] (low) -| (up);
+  \draw[arc] (up) |- (high);
+  {% if state["low"] == 1 %}
+  \node at (2.5,1) {\includegraphics[width=2cm]{../chap2/low}};
+  {% else %}  
+  \node at (2.5,1) {\includegraphics[width=2cm]{../chap2/high}};
+  {% endif %}
+\end{tikzpicture}
+
+%%/FRAME
+
+\end{document}

+\documentclass[multi={tikzpicture},crop=true,border=5pt]{standalone}
+
+\usepackage[utf8]{inputenc}
+
+\usepackage{verbatim}
+\usepackage{tikz}
+\usetikzlibrary{shapes,arrows,arrows.meta,petri}
+\tikzset{
+  >=latex,
+  every place/.style={minimum size=6mm},
+  every transition/.style={minimum size=6mm},
+  token distance=6pt,
+}
+
+\tikzstyle{trans}=[transition]
+
+\tikzstyle{arc}=[->,rounded corners]
+
+\tikzstyle{state}=[draw=blue!50!gray!50!white,
+  fill=blue!70!gray!10!white,
+  line width=2pt,
+  cloud,cloud puffs=8,
+  inner sep=-3pt]
+
+\tikzstyle{fire}=[arrows={-Straight Barb[scale=.6]},
+  shorten >=-2pt, shorten <=-1pt,
+  draw=blue!50!gray!50!white,
+  fill opacity=0,
+  text opacity=1,
+  line width=2pt,
+  line cap=round,
+  rounded corners]
+
+\tikzstyle{active}=[draw=green!50!gray!50!white,
+  fill=green!70!gray!10!white]
+
+\def\matrix #1#2#3#4#5#6#7{%
+  {\small$\begin{array}{c@{\hspace{12pt}}c}
+    \multicolumn{2}{c}{#1} \\[-6pt]
+    #2 & #3 \\[-6pt]
+    \multicolumn{2}{c}{\color{red}#4} \\[-6pt]
+    #5 & \color{red}#6 \\[-6pt]
+    \multicolumn{2}{c}{#7}
+  \end{array}$}}
+
+\begin{document}
+
+%%FRAME
+
+\begin{tikzpicture}[scale=1.2]
+  \node[trans,{{ active["approach"] }}] (approach) at (0,0) {};
+  \node[rotate=45] at (approach) {\tiny\textsf{approche}};
+  \node[place,tokens={{ state["before"] }}] (before) at (1,0) {};
+  \node[below] at (before.south) {\tiny\textsf{avant}};
+  \node[trans,{{ active["enter"] }}] (enter) at (2,0) {};
+  \node[rotate=45] at (enter) {\tiny\textsf{entre}};
+  \node[place,tokens={{ state["inside"] }}] (inside) at (3,0) {};
+  \node[below] at (inside.south) {\tiny\textsf{dedans}};
+  \node[trans,{{ active["exit"] }}] (exit) at (4,0) {};
+  \node[rotate=45] at (exit) {\tiny\textsf{sort}};
+  \node[place,tokens={{ state["far"] }}] (far) at (2,-1) {};
+  \node[below] at (far.south) {\tiny\textsf{loin}};
+  \draw[arc] (before) -- (enter);
+  \draw[arc] (enter) -- (inside);
+  \draw[arc] (inside) -- (exit);
+  \draw[arc] (exit) |- (far);
+  \draw[arc] (far) -| (approach);
+  \draw[arc] (approach) -- (before);
+  %
+  \node[place,tokens={{ state["low"] }}] (low) at (2,1) {};
+  \node[below] at (low.south) {\tiny\textsf{bas}};
+  \node[place,tokens={{ state["high"] }}] (high) at (2,3) {};
+  \node[above] at (high.north) {\tiny\textsf{haut}};
+  \node[trans,{{ active["down"] }}] (down) at (1,2) {};
+  \node[rotate=45] at (down) {\tiny\textsf{baisse}};
+  \node[trans,{{ active["up"] }}] (up) at (3,2) {};
+  \node[rotate=45] at (up) {\tiny\textsf{lève}};
+  \draw[arc] (high) -| (down);
+  \draw[arc] (down) |- (low);
+  \draw[arc] (low) -| (up);
+  \draw[arc] (up) |- (high);
+  %
+  \node[place,tokens={{ state["godown"] }}] (godown) at (0,2) {};
+  \node[above] at (godown.north) {\tiny\textsf{descendre}};
+  \draw[arc] (approach) -- (godown);
+  \draw[arc] (godown) -- (down);
+  \node[place,tokens={{ state["goup"] }}] (goup) at (4,2) {};
+  \node[above] at (goup.north) {\tiny\textsf{relever}};
+  \draw[arc] (exit) -- (goup);
+  \draw[arc] (goup) -- (up);
+  %
+  \begin{scope}[scale=2,yshift=-12mm]
+    \node[state,{{ active[0] }}] (0) at (0,0) {\matrix 1000001};
+    \node[state,{{ active[1] }}] (1) at (1,0) {\matrix 1100100};
+    \node[state,{{ active[2] }}] (2) at (2,0) {\matrix 0001100};
+    \node[state,{{ active[3] }}] (3) at (1.5,-1) {\matrix 0001010};
+    \node[state,{{ active[4] }}] (4) at (.5,-1) {\matrix 0011001};
+    \draw[fire,{{ active["approach"] }}] (0) -- node[above]{\tiny\textsf{approche}} (1);
+    \draw[fire,{{ active["down"] }}] (1) -- node[above]{\tiny\textsf{baisse}} (2);
+    \draw[fire,{{ active["enter"] }}] (2) |- node[left,pos=.1]{\tiny\textsf{entre}} (3);
+    \draw[fire,{{ active["exit"] }}] (3) -- node[above]{\tiny\textsf{sort}} (4);
+    \draw[fire,{{ active["up"] }}] (4) -| node[left,pos=.6]{\tiny\textsf{lève}} (0);
+  \end{scope}
+\end{tikzpicture}
+
+%%/FRAME
+
+\end{document}

+\documentclass[multi={tikzpicture},crop=true,border=5pt]{standalone}
+
+\usepackage[utf8]{inputenc}
+
+\usepackage{verbatim}
+\usepackage{tikz}
+\usetikzlibrary{shapes,arrows,arrows.meta,petri}
+\tikzset{
+  >=latex,
+  every place/.style={minimum size=6mm},
+  every transition/.style={minimum size=6mm},
+  token distance=6pt,
+}
+
+\tikzstyle{trans}=[transition]
+
+\tikzstyle{arc}=[->,rounded corners]
+
+\tikzstyle{state}=[draw=blue!50!gray!50!white,
+  fill=blue!70!gray!10!white,
+  line width=2pt,
+  cloud,cloud puffs=8,
+  inner sep=-1pt]
+
+\tikzstyle{fire}=[arrows={-Straight Barb[scale=.6]},
+  shorten >=-2pt, shorten <=-1pt,
+  draw=blue!50!gray!50!white,
+  line width=2pt,
+  line cap=round,
+  rounded corners]
+
+\tikzstyle{active}=[draw=green!50!gray!50!white,
+  fill=green!70!gray!10!white]
+
+\begin{document}
+
+%%FRAME
+
+\begin{tikzpicture}[scale=1.2]
+  \node[trans,{{ active["approach"] }}] (approach) at (0,0) {};
+  \node[rotate=45] at (approach) {\tiny\textsf{approche}};
+  \node[place,tokens={{ state["before"] }}] (before) at (1,0) {};
+  \node[below] at (before.south) {\tiny\textsf{avant}};
+  \node[trans,{{ active["enter"] }}] (enter) at (2,0) {};
+  \node[rotate=45] at (enter) {\tiny\textsf{entre}};
+  \node[place,tokens={{ state["inside"] }}] (inside) at (3,0) {};
+  \node[below] at (inside.south) {\tiny\textsf{dedans}};
+  \node[trans,{{ active["exit"] }}] (exit) at (4,0) {};
+  \node[rotate=45] at (exit) {\tiny\textsf{sort}};
+  \node[place,tokens={{ state["far"] }}] (far) at (2,-1) {};
+  \node[below] at (far.south) {\tiny\textsf{loin}};
+  \draw[arc] (before) -- (enter);
+  \draw[arc] (enter) -- (inside);
+  \draw[arc] (inside) -- (exit);
+  \draw[arc] (exit) |- (far);
+  \draw[arc] (far) -| (approach);
+  \draw[arc] (approach) -- (before);
+  {% if state["far"] == 1 %}
+  \node at (5.5,-.5) {\includegraphics[width=2cm]{../chap2/far}};
+  {% elif state["before"] == 1 %}
+  \node at (5.5,-.5) {\includegraphics[width=2cm]{../chap2/close}};
+  {% else %}  
+  \node at (5.5,-.5) {\includegraphics[width=2cm]{../chap2/inside}};
+  {% endif %}
+\end{tikzpicture}
+
+%%/FRAME
+
+\end{document}

+import tempfile, os, os.path, inspect
+import jinja2
+
+class T2G (object) :
+    def __init__ (self, env, header, body, trailer) :
+        self.env = env
+        self.tpl = jinja2.Template(body)
+        self.trailer = trailer
+        self.frames = []
+        self.tmp = tempfile.TemporaryDirectory(suffix=".t2g", dir=os.getcwd())
+        self.out = open(os.path.join(self.tmp.name, "frames.tex"), "w")
+        self.out.write(header)
+    def frame (self, duration) :
+        env = self.env.copy()
+        self.out.write("\n%%%%%% FRAME %s\n%s\n"
+                       % (len(self.frames), self.tpl.render(**env)))
+        self.frames.append(duration * 100)
+    def gif (self, path, dpi=500) :
+        self.out.write("\n%%%%%% TRAILER\n\n%s\n" % self.trailer)
+        self.out.flush()
+        cwd = os.getcwd()
+        path = os.path.join(cwd, path)
+        try :
+            os.chdir(self.tmp.name)
+            os.system("latexmk -pdf -cd -f frames.tex")
+            print("extracting frames")
+            os.system("convert -background white -alpha remove -density %s"
+                      " frames.pdf frames.png" % dpi)
+            print("building GIF")
+            os.system("convert -layers OptimizeFrame -loop 0 %s %s"
+                      % (" ".join("-delay %s frames-%s.png" % (duration, frame)
+                                  for frame, duration in enumerate(self.frames)),
+                         path))
+            print("optimizing GIF")
+            os.system("gifsicle --batch --optimize=3 %s" % path)
+        finally :
+            os.chdir(cwd)
+
+__t2g__ = None
+
+def load (path) :
+    global __t2g__
+    txt = open(path).read()
+    header, txt = txt.split("%%FRAME")
+    body, trailer = txt.split("%%/FRAME")
+    stack = inspect.stack()
+    __t2g__ = T2G(stack[1].frame.f_globals, header, body, trailer)
+
+def frame (duration) :
+    global __t2g__
+    assert __t2g__, "no template loaded"
+    __t2g__.frame(duration)
+
+def gif (path, dpi=500) :
+    global __t2g__
+    assert __t2g__, "no template loaded"
+    __t2g__.gif(path, dpi)