From 07b3574b19cc158f5d15a4d9795eac9558877201 Mon Sep 17 00:00:00 2001
From: Laurent Rineau <laurent.rineau@cgal.org>
Date: Mon, 16 Jun 2025 12:08:21 +0200
Subject: [PATCH] add an intro to Triangulation_3 user manual

---
 .../Constrained_triangulation_3.txt           |  2 +-
 .../doc/Triangulation_3/Triangulation_3.txt   | 14 ++++++++++++++
 .../doc/Triangulation_3/dependencies          | 19 ++++++++++---------
 3 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/Constrained_triangulation_3/doc/Constrained_triangulation_3/Constrained_triangulation_3.txt b/Constrained_triangulation_3/doc/Constrained_triangulation_3/Constrained_triangulation_3.txt
index 2096f400f10..8fe80b225a6 100644
--- a/Constrained_triangulation_3/doc/Constrained_triangulation_3/Constrained_triangulation_3.txt
+++ b/Constrained_triangulation_3/doc/Constrained_triangulation_3/Constrained_triangulation_3.txt
@@ -66,7 +66,7 @@ The goal of the algorithms developed in this package is to compute a constrained
 triangulation that contains a given set of polygonal constraints in 3D as a subcomplex.
 
 A triangulation is a _Delaunay triangulation_ if the circumscribing sphere of any simplex
-in the triangulation contains no vertex in its interior (see package \ref PkgTriangulation3
+in the triangulation contains no vertex in its interior (see chapter \ref PkgTriangulation3
 for more details on Delaunay triangulations).
 
 A _constrained Delaunay triangulation_ of a PLC is a constrained triangulation that is as close as
diff --git a/Triangulation_3/doc/Triangulation_3/Triangulation_3.txt b/Triangulation_3/doc/Triangulation_3/Triangulation_3.txt
index 0e555a26767..6f1b775e79e 100644
--- a/Triangulation_3/doc/Triangulation_3/Triangulation_3.txt
+++ b/Triangulation_3/doc/Triangulation_3/Triangulation_3.txt
@@ -11,6 +11,20 @@ namespace CGAL {
 \image html triangulation3.png
 \image latex triangulation3.png
 
+This chapter describes the three-dimensional triangulations of \cgal. Section \ref
+Triangulation3secdef recalls the main definitions related to 3D triangulations. Section
+\ref Triangulation3secintro discusses how three-dimensional triangulations are represented
+in \cgal. Section \ref Triangulation3secdesign presents the overall software design of the 3D
+triangulations package. The following sections introduce the different three-dimensional
+triangulation classes available in \cgal: basic triangulations (Section \ref Triangulation3secintro),
+Delaunay triangulations (Section \ref Triangulation_3Delaunay),
+and regular triangulations (Section \ref Triangulation3secclassRegulartriangulation).
+
+The chapter \ref PkgConstrainedTriangulation3 adds 3D constrained
+Delaunay triangulations, which are built on top of the basic 3D triangulations described here.
+
+\section Triangulation3secdef Definition
+
 The basic 3D-triangulation class of \cgal is primarily designed to
 represent the triangulations of a set of points \f$ A\f$ in \f$ \mathbb{R}^3\f$. It is
 a partition of the convex hull of \f$ A\f$ into tetrahedra whose vertices
diff --git a/Triangulation_3/doc/Triangulation_3/dependencies b/Triangulation_3/doc/Triangulation_3/dependencies
index ab8f6c69aa5..f6e2628bbda 100644
--- a/Triangulation_3/doc/Triangulation_3/dependencies
+++ b/Triangulation_3/doc/Triangulation_3/dependencies
@@ -1,11 +1,12 @@
-Manual
-Kernel_23
-STL_Extension
 Algebraic_foundations
-Convex_hull_3
-Circulator
-Spatial_sorting
-Stream_support
-Triangulation_2
-TDS_3
 BGL
+Circulator
+Constrained_triangulation_3
+Convex_hull_3
+Kernel_23
+Manual
+Spatial_sorting
+STL_Extension
+Stream_support
+TDS_3
+Triangulation_2