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Edits to account for Mael's comment from last revision
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@ -11,7 +11,10 @@ namespace CGAL {
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\cgalAutoToc
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\author Iordan Iordanov & Monique Teillaud
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\image html new-triangulation-350px.png
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<center>
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<img src="new-triangulation-350px.png" style="max-width:50%; width=50%;"/>
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</center>
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This package allows to compute Delaunay triangulations of the Bolza surface, which is the
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most symmetric surface of genus 2. The Bolza surface is a hyperbolic closed compact orientable surface.
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@ -34,15 +37,11 @@ Consider the regular hyperbolic octagon \f$ \mathcal D_O \f$ centered at the ori
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all angles equal to \f$ \pi/4\f$ that is shown in
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\cgalFigureRef{P4HTriangulationOctagonId} - Left.
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Note that \f$\mathcal D_O\f$ is unique up to rotation, and cannot
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be scaled, since this operation would change its angles.
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Now, consider the
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be scaled, since this operation would change its angles. Consider the
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four hyperbolic translations \f$ a,b,c,d\f$ with their respective inverses \f$\overline{a},
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\overline{b}, \overline{c}, \overline{d}\f$ that identify the opposite sides of
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\f$ \mathcal D_O \f$. The axes of these translations are diameters of the Poincaré disk.
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See \cgalFigureRef{P4HTriangulationOctagonId} - Left.
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The four translations
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See \cgalFigureRef{P4HTriangulationOctagonId} - Left. The four translations
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\f$a, b, c, d\f$ generate a (non-commutative) discrete group of orientation-preserving isometries, with
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finite presentation
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\f[ \mathcal{G} = \left< a,b,c,d \; \bigg| \;
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@ -79,7 +78,6 @@ onto \f$\mathcal M\f$.
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By definition, all points of \f$\mathbb H^2\f$ that belong to the same
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orbit under the action of \f$\mathcal G\f$ project by \f$\pi\f$ onto
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the same point of the surface \f$\mathcal M\f$.
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The half-open octagon \f$\mathcal D\f$ shown in
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\cgalFigureRef{P4HTriangulationOctagonId} - Right contains exactly one
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<i>representative</i> of each point of \f$\mathcal{M}\f$;
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@ -130,7 +128,7 @@ outside \f$\mathcal D\f$. Such faces can be uniquely specified by
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three pairs of points in \f$\mathcal D\f$ and (reduced) translations
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of \f$\mathcal{G}\f$; points in the original domain are paired with
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the identity translation \f$\mathbb 1\f$. The underlying combinatorial
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triangulation is a \ref PkgTDS2Summary, enriched in each face by the
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triangulation is a \ref PkgTDS2, enriched in each face by the
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three translations that are paired with the point in each vertex. See
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\cgalFigureRef{P4HTriangulationOrientationDS}.
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@ -239,10 +237,6 @@ dummy points necessary to guarantee that the triangulation is a simplicial compl
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\section P4HT2_design Software Design
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\cgalModifBegin
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TODO enlever les redondances dans cette section et améliorer la structure [modified, à discuter]
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\cgalModifEnd
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The main class of this package is `Periodic_4_hyperbolic_Delaunay_triangulation_2`, which
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implements Delaunay triangulations of the Bolza surface \f$\mathcal M\f$. The prefix
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"Periodic_4" emphasizes that the triangulation in the universal covering \f$\mathbb H^2\f$
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@ -279,14 +273,11 @@ the triangulation. See Section \ref P4HT2_datastructure.
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\subsection P4HT2_traits The Geometric Traits Parameter
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\cgalModifBegin
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The geometric traits class must fulfill the requirements described in the concept
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`Periodic_4HyperbolicDelaunayTriangulationTraits_2`. It must provide all necessary objects,
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predicates, and constructions for the computation of Delaunay triangulations of the Bolza surface.
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Moreover, the traits class must represent hyperbolic translations of the group \f$\mathcal G\f$
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via the class `Hyperbolic_octagon_translation`.
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\cgalModifEnd
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A model for the concept `Periodic_4HyperbolicDelaunayTriangulationTraits_2` offered by this
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package is the class `Periodic_4_hyperbolic_Delaunay_triangulation_traits_2`. The class requires
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@ -309,8 +300,8 @@ This model is itself parameterized by a vertex
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base class and a face base class, which gives the possibility to customize the vertices and
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faces used by the triangulation data structure. To represent periodic hyperbolic triangulations,
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the face base and vertex base classes must be models of the concepts
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`Periodic_4HyperbolicTriangulationDSFaceBase_2` and
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`Periodic_4HyperbolicTriangulationDSVertexBase_2`, respectively.
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`Periodic_4HyperbolicTriangulationFaceBase_2` and
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`Periodic_4HyperbolicTriangulationVertexBase_2`, respectively.
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The default value for the triangulation data structure parameter in the class
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`Periodic_4_hyperbolic_Delaunay_triangulation_2` is
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@ -370,7 +361,7 @@ have been executed on two machines:
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</center>
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Another experiment shows that, on average, all dummy points are removed
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from the triangulation with the insertion of less than 200 random points uniformly distributed
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from the triangulation with the insertion of fewer than 200 random points uniformly distributed
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in the unit disk with respect to the Euclidean metric \cgalCite{cgal:it-idtbs-17}.
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We start with an empty triangulation of the Bolza
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surface (i.e., initialized with only the dummy points), and we start inserting random points
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