visualize self-crossing

IV/Makefile

@@ -9,7 +9,9 @@ FIGURES = fig8-definition-of-a-bend.pdf \
 		  fig5-gentle-inflection-before.pdf \
 		  fig5-gentle-inflection-after.pdf \
 		  inflection-1-gentle-inflection-before.pdf \
-		  inflection-1-gentle-inflection-after.pdf
+		  inflection-1-gentle-inflection-after.pdf \
+			fig6-self-crossing-before.pdf \
+			fig6-self-crossing-after.pdf
 
 .PHONY: test
 test: .faux_test
@@ -113,6 +115,21 @@ inflection-1-gentle-inflection-after.pdf: layer2img.py Makefile .faux_test
 		--group2-where="name='inflection-1' AND stage='cinflections-polygon' AND gen=1" \
 		--outfile=$@
 
+fig6-self-crossing-before.pdf: layer2img.py Makefile .faux_test
+	python ./layer2img.py \
+		--widthdiv=4 \
+		--group1-table=wm_debug \
+		--group1-where="name='fig6' AND stage='bbends' AND gen=1" \
+		--group2-table=wm_visuals \
+		--group2-where="name='fig6-baseline'" \
+		--outfile=$@
+
+fig6-self-crossing-after.pdf: layer2img.py Makefile .faux_test
+	python ./layer2img.py \
+		--widthdiv=4 \
+		--group1-table=wm_debug \
+		--group1-where="name='fig6' AND stage='dcrossings' AND gen=1" \
+		--outfile=$@
 
 .faux_test: tests.sql wm.sql .faux_db
 	./db -f tests.sql

IV/mj-msc.tex

@@ -409,7 +409,23 @@ The "quite small angle" was arbitrarily chosen to $\smallAngle$.
 \subsection{Self-line Crossing When Cutting a Bend}
 
 When bend's baseline crosses another bend, it is called self-crossing. This is
-undesirable in the upcoming operators, and self-crossings should be removed.
+undesirable in the upcoming operators, and self-crossings should be removed
+following the rules of the article.
+
+\begin{figure}[h]
+    \centering
+    \begin{subfigure}[b]{.4\textwidth}
+        \includegraphics[width=\textwidth]{fig6-self-crossing-before}
+        \caption{Bend's baseline is crossing another bend}
+    \end{subfigure}
+    \hfill
+    \begin{subfigure}[b]{.4\textwidth}
+        \includegraphics[width=\textwidth]{fig6-self-crossing-after}
+        \caption{Bend's baseline is crossing another bend}
+    \end{subfigure}
+    \caption{Originally Figure 6: self-line crossing}
+    \label{fig:fig6-self-crossing}
+\end{figure}
 
 \subsection{Attributes of a Single Bend}
 

IV/tests.sql

@@ -53,6 +53,16 @@ drop table if exists wm_demo;
 create table wm_demo (name text, i bigint, way geometry);
 insert into wm_demo (name, way) select name, ST_SimplifyWM(way, name) from wm_figures;
 
+-- wm_visuals holds visual aids for the paper.
+drop table if exists wm_visuals;
+create table wm_visuals (name text, way geometry);
+do $$
+  declare fig6 geometry;
+begin
+  select way from wm_debug where name='fig6' and stage='bbends' and gen=1 into fig6 limit 1 offset 2;
+  insert into wm_visuals (name, way) values('fig6-baseline', st_makeline(st_startpoint(fig6), st_endpoint(fig6)));
+end $$ language plpgsql;
+
 do $$
 declare
   vbends geometry[];