From 5679540c85465eb67965fdbc95ca5460668c2b78 Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@klayout.de>
Date: Wed, 16 Aug 2023 22:21:49 +0200
Subject: [PATCH] Some refactoring

---
 src/db/db/dbTriangle.cc  | 12 ++++++++++++
 src/db/db/dbTriangle.h   |  5 +++++
 src/db/db/dbTriangles.cc |  2 +-
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/db/db/dbTriangle.cc b/src/db/db/dbTriangle.cc
index bb7c73910..e8da0ae0f 100644
--- a/src/db/db/dbTriangle.cc
+++ b/src/db/db/dbTriangle.cc
@@ -476,6 +476,18 @@ Triangle::find_edge_with (const Vertex *v1, const Vertex *v2) const
   tl_assert (false);
 }
 
+TriangleEdge *
+Triangle::common_edge (const Triangle *other) const
+{
+  for (int i = 0; i < 3; ++i) {
+    TriangleEdge *e = edge (i);
+    if (e->other (this) == other) {
+      return e;
+    }
+  }
+  return 0;
+}
+
 int
 Triangle::contains (const db::DPoint &point) const
 {
diff --git a/src/db/db/dbTriangle.h b/src/db/db/dbTriangle.h
index ff39ab837..ae050b19a 100644
--- a/src/db/db/dbTriangle.h
+++ b/src/db/db/dbTriangle.h
@@ -476,6 +476,11 @@ public:
    */
   TriangleEdge *find_edge_with (const Vertex *v1, const Vertex *v2) const;
 
+  /**
+   *  @brief Finds the common edge for both triangles
+   */
+  TriangleEdge *common_edge (const Triangle *other) const;
+
   /**
    *  @brief Returns a value indicating whether the point is inside (1), on the triangle (0) or outside (-1)
    */
diff --git a/src/db/db/dbTriangles.cc b/src/db/db/dbTriangles.cc
index dd04c56cf..ea8e4aeb9 100644
--- a/src/db/db/dbTriangles.cc
+++ b/src/db/db/dbTriangles.cc
@@ -338,7 +338,7 @@ Triangles::insert (db::Vertex *vertex, std::list<tl::weak_ptr<db::Triangle> > *n
     return vertex;
   }
 
-  //  the new vertex is on the edge between two triangles
+  //  check, if the new vertex is on an edge (may be edge between triangles or edge on outside)
   std::vector<db::TriangleEdge *> on_edges;
   for (int i = 0; i < 3; ++i) {
     db::TriangleEdge *e = tris.front ()->edge (i);