From 7d1fdc785e86eb5ade3fc606def3485589f5e95c Mon Sep 17 00:00:00 2001
From: Frank Staals <frank@fstaals.net>
Date: Sat, 14 Sep 2024 16:58:37 +0200
Subject: [PATCH] some more testscases

---
 .../Plane/LowerEnvelope/foo_debug_out.ipe     | 224 ++++++++++
 .../LowerEnvelope/foo_simple1_graph_out.ipe   | 413 ++++++++++++++++++
 .../LowerEnvelope/foo_simple_graph_out.ipe    | 328 ++++++++++++++
 .../VoronoiDiagram/foo_debug.ipe              | 330 ++++++++++++++
 .../VoronoiDiagram/foo_issue.ipe              | 331 ++++++++++++++
 .../VoronoiDiagram/foo_simple.ipe             | 327 ++++++++++++++
 .../VoronoiDiagram/foo_simple1.ipe            | 329 ++++++++++++++
 .../test/Plane/LowerEnvelopeSpec.hs           |  20 +
 8 files changed, 2302 insertions(+)
 create mode 100644 hgeometry/data/test-with-ipe/Plane/LowerEnvelope/foo_debug_out.ipe
 create mode 100644 hgeometry/data/test-with-ipe/Plane/LowerEnvelope/foo_simple1_graph_out.ipe
 create mode 100644 hgeometry/data/test-with-ipe/Plane/LowerEnvelope/foo_simple_graph_out.ipe
 create mode 100644 hgeometry/data/test-with-ipe/VoronoiDiagram/foo_debug.ipe
 create mode 100644 hgeometry/data/test-with-ipe/VoronoiDiagram/foo_issue.ipe
 create mode 100644 hgeometry/data/test-with-ipe/VoronoiDiagram/foo_simple.ipe
 create mode 100644 hgeometry/data/test-with-ipe/VoronoiDiagram/foo_simple1.ipe

diff --git a/hgeometry/data/test-with-ipe/Plane/LowerEnvelope/foo_debug_out.ipe b/hgeometry/data/test-with-ipe/Plane/LowerEnvelope/foo_debug_out.ipe
new file mode 100644
index 000000000..5bbaa9a16
--- /dev/null
+++ b/hgeometry/data/test-with-ipe/Plane/LowerEnvelope/foo_debug_out.ipe
@@ -0,0 +1,224 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ipe version="70005" creator="HGeometry"><ipestyle name="opacities">
+<opacity name="10%" value="0.1"/>
+<opacity name="20%" value="0.2"/>
+<opacity name="30%" value="0.3"/>
+<opacity name="40%" value="0.4"/>
+<opacity name="50%" value="0.5"/>
+<opacity name="60%" value="0.6"/>
+<opacity name="70%" value="0.7"/>
+<opacity name="80%" value="0.8"/>
+<opacity name="90%" value="0.9"/>
+</ipestyle><ipestyle name="basic">
+<color name="red" value="1 0 0"/>
+<color name="green" value="0 1 0"/>
+<color name="blue" value="0 0 1"/>
+<color name="yellow" value="1 1 0"/>
+<color name="orange" value="1 0.647 0"/>
+<color name="gold" value="1 0.843 0"/>
+<color name="purple" value="0.627 0.125 0.941"/>
+<color name="gray" value="0.745 0.745 0.745"/>
+<color name="brown" value="0.647 0.165 0.165"/>
+<color name="navy" value="0 0 0.502"/>
+<color name="pink" value="1 0.753 0.796"/>
+<color name="seagreen" value="0.18 0.545 0.341"/>
+<color name="turquoise" value="0.251 0.878 0.816"/>
+<color name="violet" value="0.933 0.51 0.933"/>
+<color name="darkblue" value="0 0 0.545"/>
+<color name="darkcyan" value="0 0.545 0.545"/>
+<color name="darkgray" value="0.663 0.663 0.663"/>
+<color name="darkgreen" value="0 0.392 0"/>
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+<dashstyle name="dotted" value="[1 3] 0"/>
+<dashstyle name="dash dotted" value="[4 2 1 2] 0"/>
+<dashstyle name="dash dot dotted" value="[4 2 1 2 1 2] 0"/>
+<pen name="heavier" value="0.8"/>
+<pen name="fat" value="1.2"/>
+<pen name="ultrafat" value="2"/>
+<textsize name="large" value="\large"/>
+<textsize name="Large" value="\Large"/>
+<textsize name="LARGE" value="\LARGE"/>
+<textsize name="huge" value="\huge"/>
+<textsize name="Huge" value="\Huge"/>
+<textsize name="small" value="\small"/>
+<textsize name="footnote" value="\footnotesize"/>
+<textsize name="tiny" value="\tiny"/>
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+<symbolsize name="tiny" value="1.1"/>
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+<arrowsize name="small" value="5"/>
+<arrowsize name="tiny" value="3"/>
+<arrowsize name="large" value="10"/>
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+<gridsize name="10 pts (~3.5 mm)" value="10"/>
+<gridsize name="20 pts (~7 mm)" value="20"/>
+<gridsize name="14 pts (~5 mm)" value="14"/>
+<gridsize name="28 pts (~10 mm)" value="28"/>
+<gridsize name="56 pts (~20 mm)" value="56"/>
+<anglesize name="90 deg" value="90"/>
+<anglesize name="60 deg" value="60"/>
+<anglesize name="45 deg" value="45"/>
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+<tiling name="rising" angle="30" width="1" step="4"/>
+<textstyle name="center" begin="\begin{center}" end="\end{center}"/>
+<textstyle name="itemize" begin="\begin{itemize}" end="\end{itemize}"/>
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\ No newline at end of file
diff --git a/hgeometry/data/test-with-ipe/Plane/LowerEnvelope/foo_simple1_graph_out.ipe b/hgeometry/data/test-with-ipe/Plane/LowerEnvelope/foo_simple1_graph_out.ipe
new file mode 100644
index 000000000..ab0dc41d3
--- /dev/null
+++ b/hgeometry/data/test-with-ipe/Plane/LowerEnvelope/foo_simple1_graph_out.ipe
@@ -0,0 +1,413 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ipe version="70005" creator="HGeometry"><ipestyle name="opacities">
+<opacity name="10%" value="0.1"/>
+<opacity name="20%" value="0.2"/>
+<opacity name="30%" value="0.3"/>
+<opacity name="40%" value="0.4"/>
+<opacity name="50%" value="0.5"/>
+<opacity name="60%" value="0.6"/>
+<opacity name="70%" value="0.7"/>
+<opacity name="80%" value="0.8"/>
+<opacity name="90%" value="0.9"/>
+</ipestyle><ipestyle name="basic">
+<color name="red" value="1 0 0"/>
+<color name="green" value="0 1 0"/>
+<color name="blue" value="0 0 1"/>
+<color name="yellow" value="1 1 0"/>
+<color name="orange" value="1 0.647 0"/>
+<color name="gold" value="1 0.843 0"/>
+<color name="purple" value="0.627 0.125 0.941"/>
+<color name="gray" value="0.745 0.745 0.745"/>
+<color name="brown" value="0.647 0.165 0.165"/>
+<color name="navy" value="0 0 0.502"/>
+<color name="pink" value="1 0.753 0.796"/>
+<color name="seagreen" value="0.18 0.545 0.341"/>
+<color name="turquoise" value="0.251 0.878 0.816"/>
+<color name="violet" value="0.933 0.51 0.933"/>
+<color name="darkblue" value="0 0 0.545"/>
+<color name="darkcyan" value="0 0.545 0.545"/>
+<color name="darkgray" value="0.663 0.663 0.663"/>
+<color name="darkgreen" value="0 0.392 0"/>
+<color name="darkmagenta" value="0.545 0 0.545"/>
+<color name="darkorange" value="1 0.549 0"/>
+<color name="darkred" value="0.545 0 0"/>
+<color name="lightblue" value="0.678 0.847 0.902"/>
+<color name="lightcyan" value="0.878 1 1"/>
+<color name="lightgray" value="0.827 0.827 0.827"/>
+<color name="lightgreen" value="0.565 0.933 0.565"/>
+<color name="lightyellow" value="1 1 0.878"/>
+<dashstyle name="dashed" value="[4] 0"/>
+<dashstyle name="dotted" value="[1 3] 0"/>
+<dashstyle name="dash dotted" value="[4 2 1 2] 0"/>
+<dashstyle name="dash dot dotted" value="[4 2 1 2 1 2] 0"/>
+<pen name="heavier" value="0.8"/>
+<pen name="fat" value="1.2"/>
+<pen name="ultrafat" value="2"/>
+<textsize name="large" value="\large"/>
+<textsize name="Large" value="\Large"/>
+<textsize name="LARGE" value="\LARGE"/>
+<textsize name="huge" value="\huge"/>
+<textsize name="Huge" value="\Huge"/>
+<textsize name="small" value="\small"/>
+<textsize name="footnote" value="\footnotesize"/>
+<textsize name="tiny" value="\tiny"/>
+<symbolsize name="small" value="2"/>
+<symbolsize name="tiny" value="1.1"/>
+<symbolsize name="large" value="5"/>
+<arrowsize name="small" value="5"/>
+<arrowsize name="tiny" value="3"/>
+<arrowsize name="large" value="10"/>
+<gridsize name="4 pts" value="4"/>
+<gridsize name="8 pts (~3 mm)" value="8"/>
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+<gridsize name="32 pts (~12 mm)" value="32"/>
+<gridsize name="10 pts (~3.5 mm)" value="10"/>
+<gridsize name="20 pts (~7 mm)" value="20"/>
+<gridsize name="14 pts (~5 mm)" value="14"/>
+<gridsize name="28 pts (~10 mm)" value="28"/>
+<gridsize name="56 pts (~20 mm)" value="56"/>
+<anglesize name="90 deg" value="90"/>
+<anglesize name="60 deg" value="60"/>
+<anglesize name="45 deg" value="45"/>
+<anglesize name="30 deg" value="30"/>
+<anglesize name="22.5 deg" value="22.5"/>
+<symbol name="mark/circle(sx)" transformations="translations">
+<path fill="sym-stroke">
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+</path></symbol>
+<symbol name="mark/disk(sx)" transformations="translations">
+<path fill="sym-stroke">
+0.6 0 0 0.6 0 0 e
+</path></symbol>
+<symbol name="mark/fdisk(sfx)" transformations="translations">
+<group><path fill="sym-fill">
+0.5 0 0 0.5 0 0 e
+</path><path fill="sym-stroke" fillrule="eofill">
+0.6 0 0 0.6 0 0 e 0.4 0 0 0.4 0 0 e
+</path></group></symbol>
+<symbol name="mark/box(sx)" transformations="translations">
+<path fill="sym-stroke" fillrule="eofill">
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+-0.4 -0.4 m 0.4 -0.4 l 0.4 0.4 l -0.4 0.4 l h</path></symbol>
+<symbol name="mark/square(sx)" transformations="translations">
+<path fill="sym-stroke">
+-0.6 -0.6 m 0.6 -0.6 l 0.6 0.6 l -0.6 0.6 l h</path></symbol>
+<symbol name="mark/fsquare(sfx)" transformations="translations">
+<group><path fill="sym-fill">
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+<path fill="sym-stroke" fillrule="eofill">
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diff --git a/hgeometry/data/test-with-ipe/Plane/LowerEnvelope/foo_simple_graph_out.ipe b/hgeometry/data/test-with-ipe/Plane/LowerEnvelope/foo_simple_graph_out.ipe
new file mode 100644
index 000000000..c41a275cc
--- /dev/null
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diff --git a/hgeometry/data/test-with-ipe/VoronoiDiagram/foo_debug.ipe b/hgeometry/data/test-with-ipe/VoronoiDiagram/foo_debug.ipe
new file mode 100644
index 000000000..78c668cea
--- /dev/null
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+<textsize name="Huge" value="\Huge"/>
+<textsize name="LARGE" value="\LARGE"/>
+<textsize name="Large" value="\Large"/>
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+<textsize name="huge" value="\huge"/>
+<textsize name="large" value="\large"/>
+<textsize name="script" value="\scriptsize"/>
+<textsize name="small" value="\small"/>
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+<tiling name="falling" angle="-60" step="4" width="1"/>
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+</ipestyle>
+<page>
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+<use name="mark/disk(sx)" pos="144 384" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="480 384" size="normal" stroke="black"/>
+</page>
+</ipe>
diff --git a/hgeometry/data/test-with-ipe/VoronoiDiagram/foo_issue.ipe b/hgeometry/data/test-with-ipe/VoronoiDiagram/foo_issue.ipe
new file mode 100644
index 000000000..0c3743b7c
--- /dev/null
+++ b/hgeometry/data/test-with-ipe/VoronoiDiagram/foo_issue.ipe
@@ -0,0 +1,331 @@
+<?xml version="1.0"?>
+<!DOCTYPE ipe SYSTEM "ipe.dtd">
+<ipe version="70218" creator="Ipe 7.2.28">
+<info created="D:20240210171226" modified="D:20240914162810"/>
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+</symbol>
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+<use name="mark/disk(sx)" pos="144 384" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="480 384" size="normal" stroke="black"/>
+</page>
+</ipe>
diff --git a/hgeometry/data/test-with-ipe/VoronoiDiagram/foo_simple.ipe b/hgeometry/data/test-with-ipe/VoronoiDiagram/foo_simple.ipe
new file mode 100644
index 000000000..c0d582fcd
--- /dev/null
+++ b/hgeometry/data/test-with-ipe/VoronoiDiagram/foo_simple.ipe
@@ -0,0 +1,327 @@
+<?xml version="1.0"?>
+<!DOCTYPE ipe SYSTEM "ipe.dtd">
+<ipe version="70218" creator="Ipe 7.2.28">
+<info created="D:20240210171226" modified="D:20240914160242"/>
+<ipestyle name="basic">
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+</path>
+</symbol>
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+</path>
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+<symbol name="arrow/ptarc(spx)">
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+</path>
+</symbol>
+<symbol name="mark/circle(sx)" transformations="translations">
+<path fill="sym-stroke">
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+0.4 0 0 0.4 0 0 e
+</path>
+</symbol>
+<symbol name="mark/disk(sx)" transformations="translations">
+<path fill="sym-stroke">
+0.6 0 0 0.6 0 0 e
+</path>
+</symbol>
+<symbol name="mark/fdisk(sfx)" transformations="translations">
+<group>
+<path fill="sym-fill">
+0.5 0 0 0.5 0 0 e
+</path>
+<path fill="sym-stroke" fillrule="eofill">
+0.6 0 0 0.6 0 0 e
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+</path>
+</group>
+</symbol>
+<symbol name="mark/box(sx)" transformations="translations">
+<path fill="sym-stroke" fillrule="eofill">
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+</symbol>
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+</path>
+</symbol>
+<symbol name="mark/fsquare(sfx)" transformations="translations">
+<group>
+<path fill="sym-fill">
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+</path>
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+</path>
+</group>
+</symbol>
+<symbol name="mark/cross(sx)" transformations="translations">
+<group>
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+</path>
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+h
+</path>
+</group>
+</symbol>
+<symbol name="arrow/fnormal(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0 0 m
+-1 0.333 l
+-1 -0.333 l
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+</path>
+</symbol>
+<symbol name="arrow/pointed(spx)">
+<path stroke="sym-stroke" fill="sym-stroke" pen="sym-pen">
+0 0 m
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+-1 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/fpointed(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0 0 m
+-1 0.333 l
+-0.8 0 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/linear(spx)">
+<path stroke="sym-stroke" pen="sym-pen">
+-1 0.333 m
+0 0 l
+-1 -0.333 l
+</path>
+</symbol>
+<symbol name="arrow/fdouble(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0 0 m
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+</path>
+</symbol>
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+0 0 m
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+h
+-1 0 m
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+</path>
+</symbol>
+<symbol name="arrow/mid-normal(spx)">
+<path stroke="sym-stroke" fill="sym-stroke" pen="sym-pen">
+0.5 0 m
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+-0.5 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/mid-fnormal(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0.5 0 m
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+h
+</path>
+</symbol>
+<symbol name="arrow/mid-pointed(spx)">
+<path stroke="sym-stroke" fill="sym-stroke" pen="sym-pen">
+0.5 0 m
+-0.5 0.333 l
+-0.3 0 l
+-0.5 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/mid-fpointed(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0.5 0 m
+-0.5 0.333 l
+-0.3 0 l
+-0.5 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/mid-double(spx)">
+<path stroke="sym-stroke" fill="sym-stroke" pen="sym-pen">
+1 0 m
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+0 -0.333 l
+h
+0 0 m
+-1 0.333 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/mid-fdouble(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+1 0 m
+0 0.333 l
+0 -0.333 l
+h
+0 0 m
+-1 0.333 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<anglesize name="22.5 deg" value="22.5"/>
+<anglesize name="30 deg" value="30"/>
+<anglesize name="45 deg" value="45"/>
+<anglesize name="60 deg" value="60"/>
+<anglesize name="90 deg" value="90"/>
+<arrowsize name="large" value="10"/>
+<arrowsize name="small" value="5"/>
+<arrowsize name="tiny" value="3"/>
+<color name="blue" value="0 0 1"/>
+<color name="brown" value="0.647 0.165 0.165"/>
+<color name="darkblue" value="0 0 0.545"/>
+<color name="darkcyan" value="0 0.545 0.545"/>
+<color name="darkgray" value="0.663"/>
+<color name="darkgreen" value="0 0.392 0"/>
+<color name="darkmagenta" value="0.545 0 0.545"/>
+<color name="darkorange" value="1 0.549 0"/>
+<color name="darkred" value="0.545 0 0"/>
+<color name="gold" value="1 0.843 0"/>
+<color name="gray" value="0.745"/>
+<color name="green" value="0 1 0"/>
+<color name="lightblue" value="0.678 0.847 0.902"/>
+<color name="lightcyan" value="0.878 1 1"/>
+<color name="lightgray" value="0.827"/>
+<color name="lightgreen" value="0.565 0.933 0.565"/>
+<color name="lightyellow" value="1 1 0.878"/>
+<color name="navy" value="0 0 0.502"/>
+<color name="orange" value="1 0.647 0"/>
+<color name="pink" value="1 0.753 0.796"/>
+<color name="purple" value="0.627 0.125 0.941"/>
+<color name="red" value="1 0 0"/>
+<color name="seagreen" value="0.18 0.545 0.341"/>
+<color name="turquoise" value="0.251 0.878 0.816"/>
+<color name="violet" value="0.933 0.51 0.933"/>
+<color name="yellow" value="1 1 0"/>
+<dashstyle name="dash dot dotted" value="[4 2 1 2 1 2] 0"/>
+<dashstyle name="dash dotted" value="[4 2 1 2] 0"/>
+<dashstyle name="dashed" value="[4] 0"/>
+<dashstyle name="dotted" value="[1 3] 0"/>
+<gridsize name="10 pts (~3.5 mm)" value="10"/>
+<gridsize name="14 pts (~5 mm)" value="14"/>
+<gridsize name="16 pts (~6 mm)" value="16"/>
+<gridsize name="20 pts (~7 mm)" value="20"/>
+<gridsize name="28 pts (~10 mm)" value="28"/>
+<gridsize name="32 pts (~12 mm)" value="32"/>
+<gridsize name="4 pts" value="4"/>
+<gridsize name="56 pts (~20 mm)" value="56"/>
+<gridsize name="8 pts (~3 mm)" value="8"/>
+<opacity name="10%" value="0.1"/>
+<opacity name="30%" value="0.3"/>
+<opacity name="50%" value="0.5"/>
+<opacity name="75%" value="0.75"/>
+<pen name="fat" value="1.2"/>
+<pen name="heavier" value="0.8"/>
+<pen name="ultrafat" value="2"/>
+<symbolsize name="large" value="5"/>
+<symbolsize name="small" value="2"/>
+<symbolsize name="tiny" value="1.1"/>
+<textsize name="Huge" value="\Huge"/>
+<textsize name="LARGE" value="\LARGE"/>
+<textsize name="Large" value="\Large"/>
+<textsize name="footnote" value="\footnotesize"/>
+<textsize name="huge" value="\huge"/>
+<textsize name="large" value="\large"/>
+<textsize name="script" value="\scriptsize"/>
+<textsize name="small" value="\small"/>
+<textsize name="tiny" value="\tiny"/>
+<textstyle name="center" begin="\begin{center}" end="\end{center}"/>
+<textstyle name="item" begin="\begin{itemize}\item{}" end="\end{itemize}"/>
+<textstyle name="itemize" begin="\begin{itemize}" end="\end{itemize}"/>
+<tiling name="falling" angle="-60" step="4" width="1"/>
+<tiling name="rising" angle="30" step="4" width="1"/>
+</ipestyle>
+<page>
+<layer name="alpha"/>
+<view layers="alpha" active="alpha"/>
+<use layer="alpha" name="mark/disk(sx)" pos="48 96" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="80 224" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="176 96" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="320 96" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="288 240" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="400 192" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="336 272" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="192 288" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="304 448" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="144 384" size="normal" stroke="black"/>
+</page>
+</ipe>
diff --git a/hgeometry/data/test-with-ipe/VoronoiDiagram/foo_simple1.ipe b/hgeometry/data/test-with-ipe/VoronoiDiagram/foo_simple1.ipe
new file mode 100644
index 000000000..f14d82fe4
--- /dev/null
+++ b/hgeometry/data/test-with-ipe/VoronoiDiagram/foo_simple1.ipe
@@ -0,0 +1,329 @@
+<?xml version="1.0"?>
+<!DOCTYPE ipe SYSTEM "ipe.dtd">
+<ipe version="70218" creator="Ipe 7.2.28">
+<info created="D:20240210171226" modified="D:20240914161908"/>
+<ipestyle name="basic">
+<symbol name="arrow/arc(spx)">
+<path stroke="sym-stroke" fill="sym-stroke" pen="sym-pen">
+0 0 m
+-1 0.333 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/farc(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0 0 m
+-1 0.333 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/ptarc(spx)">
+<path stroke="sym-stroke" fill="sym-stroke" pen="sym-pen">
+0 0 m
+-1 0.333 l
+-0.8 0 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/fptarc(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0 0 m
+-1 0.333 l
+-0.8 0 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="mark/circle(sx)" transformations="translations">
+<path fill="sym-stroke">
+0.6 0 0 0.6 0 0 e
+0.4 0 0 0.4 0 0 e
+</path>
+</symbol>
+<symbol name="mark/disk(sx)" transformations="translations">
+<path fill="sym-stroke">
+0.6 0 0 0.6 0 0 e
+</path>
+</symbol>
+<symbol name="mark/fdisk(sfx)" transformations="translations">
+<group>
+<path fill="sym-fill">
+0.5 0 0 0.5 0 0 e
+</path>
+<path fill="sym-stroke" fillrule="eofill">
+0.6 0 0 0.6 0 0 e
+0.4 0 0 0.4 0 0 e
+</path>
+</group>
+</symbol>
+<symbol name="mark/box(sx)" transformations="translations">
+<path fill="sym-stroke" fillrule="eofill">
+-0.6 -0.6 m
+0.6 -0.6 l
+0.6 0.6 l
+-0.6 0.6 l
+h
+-0.4 -0.4 m
+0.4 -0.4 l
+0.4 0.4 l
+-0.4 0.4 l
+h
+</path>
+</symbol>
+<symbol name="mark/square(sx)" transformations="translations">
+<path fill="sym-stroke">
+-0.6 -0.6 m
+0.6 -0.6 l
+0.6 0.6 l
+-0.6 0.6 l
+h
+</path>
+</symbol>
+<symbol name="mark/fsquare(sfx)" transformations="translations">
+<group>
+<path fill="sym-fill">
+-0.5 -0.5 m
+0.5 -0.5 l
+0.5 0.5 l
+-0.5 0.5 l
+h
+</path>
+<path fill="sym-stroke" fillrule="eofill">
+-0.6 -0.6 m
+0.6 -0.6 l
+0.6 0.6 l
+-0.6 0.6 l
+h
+-0.4 -0.4 m
+0.4 -0.4 l
+0.4 0.4 l
+-0.4 0.4 l
+h
+</path>
+</group>
+</symbol>
+<symbol name="mark/cross(sx)" transformations="translations">
+<group>
+<path fill="sym-stroke">
+-0.43 -0.57 m
+0.57 0.43 l
+0.43 0.57 l
+-0.57 -0.43 l
+h
+</path>
+<path fill="sym-stroke">
+-0.43 0.57 m
+0.57 -0.43 l
+0.43 -0.57 l
+-0.57 0.43 l
+h
+</path>
+</group>
+</symbol>
+<symbol name="arrow/fnormal(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0 0 m
+-1 0.333 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/pointed(spx)">
+<path stroke="sym-stroke" fill="sym-stroke" pen="sym-pen">
+0 0 m
+-1 0.333 l
+-0.8 0 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/fpointed(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0 0 m
+-1 0.333 l
+-0.8 0 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/linear(spx)">
+<path stroke="sym-stroke" pen="sym-pen">
+-1 0.333 m
+0 0 l
+-1 -0.333 l
+</path>
+</symbol>
+<symbol name="arrow/fdouble(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0 0 m
+-1 0.333 l
+-1 -0.333 l
+h
+-1 0 m
+-2 0.333 l
+-2 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/double(spx)">
+<path stroke="sym-stroke" fill="sym-stroke" pen="sym-pen">
+0 0 m
+-1 0.333 l
+-1 -0.333 l
+h
+-1 0 m
+-2 0.333 l
+-2 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/mid-normal(spx)">
+<path stroke="sym-stroke" fill="sym-stroke" pen="sym-pen">
+0.5 0 m
+-0.5 0.333 l
+-0.5 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/mid-fnormal(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0.5 0 m
+-0.5 0.333 l
+-0.5 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/mid-pointed(spx)">
+<path stroke="sym-stroke" fill="sym-stroke" pen="sym-pen">
+0.5 0 m
+-0.5 0.333 l
+-0.3 0 l
+-0.5 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/mid-fpointed(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+0.5 0 m
+-0.5 0.333 l
+-0.3 0 l
+-0.5 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/mid-double(spx)">
+<path stroke="sym-stroke" fill="sym-stroke" pen="sym-pen">
+1 0 m
+0 0.333 l
+0 -0.333 l
+h
+0 0 m
+-1 0.333 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<symbol name="arrow/mid-fdouble(spx)">
+<path stroke="sym-stroke" fill="white" pen="sym-pen">
+1 0 m
+0 0.333 l
+0 -0.333 l
+h
+0 0 m
+-1 0.333 l
+-1 -0.333 l
+h
+</path>
+</symbol>
+<anglesize name="22.5 deg" value="22.5"/>
+<anglesize name="30 deg" value="30"/>
+<anglesize name="45 deg" value="45"/>
+<anglesize name="60 deg" value="60"/>
+<anglesize name="90 deg" value="90"/>
+<arrowsize name="large" value="10"/>
+<arrowsize name="small" value="5"/>
+<arrowsize name="tiny" value="3"/>
+<color name="blue" value="0 0 1"/>
+<color name="brown" value="0.647 0.165 0.165"/>
+<color name="darkblue" value="0 0 0.545"/>
+<color name="darkcyan" value="0 0.545 0.545"/>
+<color name="darkgray" value="0.663"/>
+<color name="darkgreen" value="0 0.392 0"/>
+<color name="darkmagenta" value="0.545 0 0.545"/>
+<color name="darkorange" value="1 0.549 0"/>
+<color name="darkred" value="0.545 0 0"/>
+<color name="gold" value="1 0.843 0"/>
+<color name="gray" value="0.745"/>
+<color name="green" value="0 1 0"/>
+<color name="lightblue" value="0.678 0.847 0.902"/>
+<color name="lightcyan" value="0.878 1 1"/>
+<color name="lightgray" value="0.827"/>
+<color name="lightgreen" value="0.565 0.933 0.565"/>
+<color name="lightyellow" value="1 1 0.878"/>
+<color name="navy" value="0 0 0.502"/>
+<color name="orange" value="1 0.647 0"/>
+<color name="pink" value="1 0.753 0.796"/>
+<color name="purple" value="0.627 0.125 0.941"/>
+<color name="red" value="1 0 0"/>
+<color name="seagreen" value="0.18 0.545 0.341"/>
+<color name="turquoise" value="0.251 0.878 0.816"/>
+<color name="violet" value="0.933 0.51 0.933"/>
+<color name="yellow" value="1 1 0"/>
+<dashstyle name="dash dot dotted" value="[4 2 1 2 1 2] 0"/>
+<dashstyle name="dash dotted" value="[4 2 1 2] 0"/>
+<dashstyle name="dashed" value="[4] 0"/>
+<dashstyle name="dotted" value="[1 3] 0"/>
+<gridsize name="10 pts (~3.5 mm)" value="10"/>
+<gridsize name="14 pts (~5 mm)" value="14"/>
+<gridsize name="16 pts (~6 mm)" value="16"/>
+<gridsize name="20 pts (~7 mm)" value="20"/>
+<gridsize name="28 pts (~10 mm)" value="28"/>
+<gridsize name="32 pts (~12 mm)" value="32"/>
+<gridsize name="4 pts" value="4"/>
+<gridsize name="56 pts (~20 mm)" value="56"/>
+<gridsize name="8 pts (~3 mm)" value="8"/>
+<opacity name="10%" value="0.1"/>
+<opacity name="30%" value="0.3"/>
+<opacity name="50%" value="0.5"/>
+<opacity name="75%" value="0.75"/>
+<pen name="fat" value="1.2"/>
+<pen name="heavier" value="0.8"/>
+<pen name="ultrafat" value="2"/>
+<symbolsize name="large" value="5"/>
+<symbolsize name="small" value="2"/>
+<symbolsize name="tiny" value="1.1"/>
+<textsize name="Huge" value="\Huge"/>
+<textsize name="LARGE" value="\LARGE"/>
+<textsize name="Large" value="\Large"/>
+<textsize name="footnote" value="\footnotesize"/>
+<textsize name="huge" value="\huge"/>
+<textsize name="large" value="\large"/>
+<textsize name="script" value="\scriptsize"/>
+<textsize name="small" value="\small"/>
+<textsize name="tiny" value="\tiny"/>
+<textstyle name="center" begin="\begin{center}" end="\end{center}"/>
+<textstyle name="item" begin="\begin{itemize}\item{}" end="\end{itemize}"/>
+<textstyle name="itemize" begin="\begin{itemize}" end="\end{itemize}"/>
+<tiling name="falling" angle="-60" step="4" width="1"/>
+<tiling name="rising" angle="30" step="4" width="1"/>
+</ipestyle>
+<page>
+<layer name="alpha"/>
+<view layers="alpha" active="alpha"/>
+<use layer="alpha" name="mark/disk(sx)" pos="48 96" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="80 224" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="192 160" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="176 96" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="320 96" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="288 240" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="336 272" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="192 288" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="448 80" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="304 448" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="144 384" size="normal" stroke="black"/>
+<use name="mark/disk(sx)" pos="480 384" size="normal" stroke="black"/>
+</page>
+</ipe>
diff --git a/hgeometry/test-with-ipe/test/Plane/LowerEnvelopeSpec.hs b/hgeometry/test-with-ipe/test/Plane/LowerEnvelopeSpec.hs
index ce6f3ab8c..7dd1dbd00 100644
--- a/hgeometry/test-with-ipe/test/Plane/LowerEnvelopeSpec.hs
+++ b/hgeometry/test-with-ipe/test/Plane/LowerEnvelopeSpec.hs
@@ -444,6 +444,8 @@ testIpeGraph inFp outFp = do
                  (addStyleSheet opacitiesStyle $ singlePageFromContent out)
 
 
+
+
 separatorTests        :: NonEmpty (Point 2 R :+ _) -> Spec
 separatorTests points = describe "separatorTests" $ do
     let vd = voronoiDiagram' $ view core <$> points
@@ -503,6 +505,24 @@ separatorTests points = describe "separatorTests" $ do
 
 
 
+-- FIXME: write some proper shrinker; since apparently we may return something that is
+-- not a separator
+
+-- separatorIsSeparatorTest = prop "separator is a separator" $
+--                              \(MyGraph gr) -> separatorIsSeparator gr
+
+
+separatorIsSeparator gr = null crossingEdges
+  where
+    (Separator sep as bs)  = Set.fromList <$> planarSeparator gr
+    crossingEdges = [ e
+                    | e@(u,v) <- toList (graphEdges gr)
+                    ,    (u `Set.member` as && v `Set.member` bs)
+                      || (u `Set.member` bs && v `Set.member` as)
+                    ]
+
+
+
 
 shouldBeAtMost     :: (Ord a, Show a, HasCallStack) => a -> a -> Expectation
 shouldBeAtMost x y = shouldSatisfy x (<= y)