From 8b14f399c1455e489a08fdef5ecd9fd3ab445eec Mon Sep 17 00:00:00 2001
From: Matthias Hochsteger <mhochsteger@cerbsim.com>
Date: Tue, 3 Nov 2020 18:42:04 +0100
Subject: [PATCH] csg2d - fix bug in getNonIntersectionVertex()

If a loop has no non-intersecting vertex, a new one is inserted
-> set all vertex properties correctly (info, spline)
---
 libsrc/geom2d/csg2d.cpp | 33 +++++++++++++++++++++++++++++++++
 libsrc/geom2d/csg2d.hpp | 26 +++++---------------------
 2 files changed, 38 insertions(+), 21 deletions(-)

diff --git a/libsrc/geom2d/csg2d.cpp b/libsrc/geom2d/csg2d.cpp
index a96986b8..01e20981 100644
--- a/libsrc/geom2d/csg2d.cpp
+++ b/libsrc/geom2d/csg2d.cpp
@@ -1565,6 +1565,39 @@ Solid2d ClipSolids ( Solid2d && s1, Solid2d && s2, char op)
   return std::move(res);
 }
 
+Vertex* Loop :: getNonIntersectionVertex()
+  {
+    for (Vertex* v : Vertices(ALL))
+      if (!v->is_intersection)
+        return(v);
+
+    // no non-intersection vertex found -> generate and return temporary vertex
+    for (Vertex* v : Vertices(ALL))
+      // make sure that edge from V to V->next is not collinear with other polygon
+      if ( (v->next->neighbour != v->neighbour->prev) && (v->next->neighbour != v->neighbour->next) )
+      {
+        // add edge midpoint as temporary vertex
+        if(v->spline)
+        {
+          auto p = v->spline->GetPoint(0.5);
+          auto s = *v->spline;
+          v->spline = Split(s, 0, 0.5);
+          auto vnew = v->Insert(p);
+          vnew->info = v->info;
+          vnew->spline = Split(s, 0.5, 1.0);
+          return vnew;
+        }
+        else
+        {
+          auto p = Center(*v, *v->next);
+          auto vnew = v->Insert(p);
+          vnew->info = v->info;
+          return vnew;
+        }
+      }
+    return(NULL);
+  }
+
 bool Loop :: IsInside( Point<2> r ) const
 {
   int w = 0;
diff --git a/libsrc/geom2d/csg2d.hpp b/libsrc/geom2d/csg2d.hpp
index 118060f8..42c44a89 100644
--- a/libsrc/geom2d/csg2d.hpp
+++ b/libsrc/geom2d/csg2d.hpp
@@ -29,10 +29,10 @@ enum IntersectionType
   T_INTERSECTION_Q,
   T_INTERSECTION_P,
   V_INTERSECTION,
-  X_OVERLAP,
-  T_OVERLAP_Q,
-  T_OVERLAP_P,
-  V_OVERLAP
+  X_OVERLAP,      // Q0 -- P1 -- Q1 -- P0   (different direction)
+  T_OVERLAP_Q,    // same direction or P inside Q
+  T_OVERLAP_P,    // same direction or Q inside P
+  V_OVERLAP       // one common point
 };
 
 enum IntersectionLabel
@@ -588,23 +588,7 @@ struct Loop
   //
   // return and insert a non-intersection vertex
   //
-  Vertex* getNonIntersectionVertex()
-  {
-    for (Vertex* v : Vertices(ALL))
-      if (!v->is_intersection)
-        return(v);
-
-    // no non-intersection vertex found -> generate and return temporary vertex
-    for (Vertex* v : Vertices(ALL))
-      // make sure that edge from V to V->next is not collinear with other polygon
-      if ( (v->next->neighbour != v->neighbour->prev) && (v->next->neighbour != v->neighbour->next) )
-      {
-        // add edge midpoint as temporary vertex
-        auto p = Center(*v, *v->next);
-        return v->Insert(p);
-      }
-    return(NULL);
-  }
+  Vertex* getNonIntersectionVertex();
 
   void SetBC(string bc)
   {