From 4f1b03496b6f273d6a416f1d20c0c47a056d9957 Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@klayout.de>
Date: Wed, 16 Apr 2025 01:15:18 +0200
Subject: [PATCH] Handling of points in Convex decomposition

---
 src/db/db/dbPLC.cc                            | 13 ++++++++
 src/db/db/dbPLC.h                             | 33 ++++++++++++++++++-
 src/db/db/dbPLCConvexDecomposition.cc         | 27 +++++++++++----
 .../dbPLCConvexDecompositionTests.cc          | 33 +++++++++++++++++++
 4 files changed, 98 insertions(+), 8 deletions(-)

diff --git a/src/db/db/dbPLC.cc b/src/db/db/dbPLC.cc
index f9572550e..d72b57362 100644
--- a/src/db/db/dbPLC.cc
+++ b/src/db/db/dbPLC.cc
@@ -542,6 +542,19 @@ Polygon::bbox () const
   return box;
 }
 
+db::DPolygon
+Polygon::polygon () const
+{
+  std::vector<db::DPoint> pts;
+  for (int i = 0; i < int (size ()); ++i) {
+    pts.push_back (*vertex (i));
+  }
+
+  db::DPolygon poly;
+  poly.assign_hull (pts.begin (), pts.end ());
+  return poly;
+}
+
 std::pair<db::DPoint, double>
 Polygon::circumcircle (bool *ok) const
 {
diff --git a/src/db/db/dbPLC.h b/src/db/db/dbPLC.h
index d5d6f0a26..ee7f1a4f0 100644
--- a/src/db/db/dbPLC.h
+++ b/src/db/db/dbPLC.h
@@ -562,7 +562,25 @@ public:
    */
   size_t size () const
   {
-    return mp_v.size ();
+    return mp_e.size ();
+  }
+
+  /**
+   *  @brief Gets the internal vertexes
+   *
+   *  Internal vertexes are special points inside the polygons.
+   */
+  size_t internal_vertexes () const
+  {
+    return mp_v.size () - mp_e.size ();
+  }
+
+  /**
+   *  @brief Adds a vertex as an internal vertex
+   */
+  void add_internal_vertex (Vertex *v)
+  {
+    mp_v.push_back (v);
   }
 
   /**
@@ -580,6 +598,14 @@ public:
     }
   }
 
+  /**
+   *  @brief Gets the nth internal vertex
+   */
+  inline Vertex *internal_vertex (size_t n) const
+  {
+    return mp_v[mp_e.size () + n];
+  }
+
   /**
    *  @brief Gets the nth edge (n wraps around and can be negative)
    */
@@ -604,6 +630,11 @@ public:
    */
   db::DBox bbox () const;
 
+  /**
+   *  @brief Returns a DPolygon object for this polygon
+   */
+  db::DPolygon polygon () const;
+
   /**
    *  @brief Gets the center point and radius of the circumcircle
    *  If ok is non-null, it will receive a boolean value indicating whether the circumcircle is valid.
diff --git a/src/db/db/dbPLCConvexDecomposition.cc b/src/db/db/dbPLCConvexDecomposition.cc
index 1905b27db..ad7c65735 100644
--- a/src/db/db/dbPLCConvexDecomposition.cc
+++ b/src/db/db/dbPLCConvexDecomposition.cc
@@ -383,12 +383,16 @@ ConvexDecomposition::hertel_mehlhorn_decomposition (Triangulation &tris, const C
     left_triangles.insert (it.operator-> ());
   }
 
-  std::list<std::vector<Edge *> > polygons;
+  std::list<std::unordered_set<Edge *> > polygons;
+  std::list<std::unordered_set<Vertex *> > internal_vertexes;
 
   while (! left_triangles.empty ()) {
 
-    polygons.push_back (std::vector<Edge *> ());
-    std::vector<Edge *> &edges = polygons.back ();
+    polygons.push_back (std::unordered_set<Edge *> ());
+    std::unordered_set<Edge *> &edges = polygons.back ();
+
+    internal_vertexes.push_back (std::unordered_set<Vertex *> ());
+    std::unordered_set<Vertex *> &ivs = internal_vertexes.back ();
 
     const Polygon *tri = *left_triangles.begin ();
     std::vector<const Polygon *> queue, next_queue;
@@ -407,8 +411,15 @@ ConvexDecomposition::hertel_mehlhorn_decomposition (Triangulation &tris, const C
           const Edge *e = (*q)->edge (i);
           const Polygon *qq = e->other (*q);
 
+          if (e->v1 ()->is_precious ()) {
+            ivs.insert (e->v1 ());
+          }
+          if (e->v2 ()->is_precious ()) {
+            ivs.insert (e->v2 ());
+          }
+
           if (! qq || essential_edges.find (e) != essential_edges.end ()) {
-            edges.push_back (const_cast<Edge *> (e));  // @@@ const_cast
+            edges.insert (const_cast<Edge *> (e));  // @@@ const_cast
           } else if (left_triangles.find (qq) != left_triangles.end ()) {
             next_queue.push_back (qq);
           }
@@ -430,8 +441,12 @@ ConvexDecomposition::hertel_mehlhorn_decomposition (Triangulation &tris, const C
 
   //  create the polygons
 
+  auto iv = internal_vertexes.begin ();
   for (auto p = polygons.begin (); p != polygons.end (); ++p) {
-    mp_graph->create_polygon (p->begin (), p->end ());
+    Polygon *poly = mp_graph->create_polygon (p->begin (), p->end ());
+    for (auto i = iv->begin (); i != iv->end (); ++i) {
+      poly->add_internal_vertex (*i); // @@@ reserve?
+    }
   }
 }
 
@@ -472,7 +487,6 @@ ConvexDecomposition::decompose (const db::Polygon &poly, const std::vector<db::P
   Triangulation tri (mp_graph);
   tri.triangulate (poly, vertexes, param, trans);
 
-  //  @@@ consider vertexes
   hertel_mehlhorn_decomposition (tri, parameters);
 }
 
@@ -501,7 +515,6 @@ ConvexDecomposition::decompose (const db::DPolygon &poly, const std::vector<db::
   Triangulation tri (mp_graph);
   tri.triangulate (poly, vertexes, param, trans);
 
-  //  @@@ consider vertexes
   hertel_mehlhorn_decomposition (tri, parameters);
 }
 
diff --git a/src/db/unit_tests/dbPLCConvexDecompositionTests.cc b/src/db/unit_tests/dbPLCConvexDecompositionTests.cc
index d2c334b4b..df2c10a89 100644
--- a/src/db/unit_tests/dbPLCConvexDecompositionTests.cc
+++ b/src/db/unit_tests/dbPLCConvexDecompositionTests.cc
@@ -110,3 +110,36 @@ TEST(basic)
   db::compare_layouts (_this, *ly, tl::testdata () + "/algo/hm_decomposition_au4.gds");
 }
 
+TEST(internal_vertex)
+{
+  db::plc::Graph plc;
+  TestableConvexDecomposition decomp (&plc);
+
+  db::Point contour[] = {
+    db::Point (0, 0),
+    db::Point (0, 100),
+    db::Point (1000, 100),
+    db::Point (1000, 0)
+  };
+
+  std::vector<db::Point> vertexes;
+  vertexes.push_back (db::Point (10, 50));
+  vertexes.push_back (db::Point (200, 70));
+
+  db::Polygon poly;
+  poly.assign_hull (contour + 0, contour + sizeof (contour) / sizeof (contour[0]));
+
+  double dbu = 0.001;
+
+  db::plc::ConvexDecompositionParameters param;
+  decomp.decompose (poly, vertexes, param, dbu);
+
+  for (auto p = plc.begin (); p != plc.end (); ++p) {
+    std::cout << p->polygon ().to_string () << std::endl; // @@@
+    for (size_t i = 0; i < p->internal_vertexes (); ++i) {
+      std::cout << "  " << p->internal_vertex (i)->to_string () << std::endl; // @@@
+    }
+  }
+
+}
+