From 83243f06bebaf1a861d188b95fd485cecd914704 Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@klayout.de>
Date: Sun, 20 Aug 2023 16:48:58 +0200
Subject: [PATCH] Triangles: solving a numerical issue

---
 src/db/db/dbTriangles.cc              |  8 +++++++-
 src/db/unit_tests/dbTrianglesTests.cc | 10 +++++-----
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/db/db/dbTriangles.cc b/src/db/db/dbTriangles.cc
index b30a524f1..42e7ae0f7 100644
--- a/src/db/db/dbTriangles.cc
+++ b/src/db/db/dbTriangles.cc
@@ -470,7 +470,7 @@ Triangles::find_closest_edge (const db::DPoint &p, db::Vertex *vstart, bool insi
 
       double ds = (*e)->distance (p);
 
-      if (d < 0.0 || ds < d) {
+      if (d < 0.0) {
 
         d = ds;
         edge = *e;
@@ -494,6 +494,12 @@ Triangles::find_closest_edge (const db::DPoint &p, db::Vertex *vstart, bool insi
           }
         }
 
+      } else if (ds < d) {
+
+        d = ds;
+        edge = *e;
+        vnext = edge->other (v);
+
       }
 
     }
diff --git a/src/db/unit_tests/dbTrianglesTests.cc b/src/db/unit_tests/dbTrianglesTests.cc
index a9d9e8a8c..45eee9612 100644
--- a/src/db/unit_tests/dbTrianglesTests.cc
+++ b/src/db/unit_tests/dbTrianglesTests.cc
@@ -875,8 +875,8 @@ TEST(triangulate_problematic)
   db::DPoint contour[] = {
     db::DPoint (129145.00000, -30060.80000),
     db::DPoint (129145.00000, -28769.50000),
-    db::DPoint (129159.50000, -28754.90000),
-    db::DPoint (129159.60000, -28754.80000),
+    db::DPoint (129159.50000, -28754.90000), //  this is a very short edge  <-- from here.
+    db::DPoint (129159.60000, -28754.80000), //  <-- to here.
     db::DPoint (129159.50000, -28754.70000),
     db::DPoint (129366.32200, -28547.90000),
     db::DPoint (130958.54600, -26955.84600),
@@ -890,7 +890,7 @@ TEST(triangulate_problematic)
 
   db::Triangles::TriangulateParameters param;
   param.min_b = 1.0;
-  param.max_area = 10000.0;
+  param.max_area = 100000.0;
   param.min_length = 0.002;
 
   TestableTriangles tri;
@@ -906,7 +906,7 @@ TEST(triangulate_problematic)
     EXPECT_GE (t->b (), param.min_b);
   }
 
-  EXPECT_GT (tri.num_triangles (), size_t (1250));
-  EXPECT_LT (tri.num_triangles (), size_t (1300));
+  EXPECT_GT (tri.num_triangles (), size_t (470));
+  EXPECT_LT (tri.num_triangles (), size_t (490));
 }