From 71a2c4f6f42aa1a21a25ed7a1955cd735f442c39 Mon Sep 17 00:00:00 2001
From: Christopher Lackner <clackner@cerbsim.com>
Date: Thu, 4 Aug 2022 10:35:06 +0200
Subject: [PATCH] do invert if periodic bc face domin & domout do not match

---
 libsrc/meshing/basegeom.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libsrc/meshing/basegeom.cpp b/libsrc/meshing/basegeom.cpp
index f5d67144..cb5b8407 100644
--- a/libsrc/meshing/basegeom.cpp
+++ b/libsrc/meshing/basegeom.cpp
@@ -976,6 +976,12 @@ namespace netgen
           }
 
     xbool do_invert = maybe;
+    if(dst.identifications[0].type == Identifications::PERIODIC)
+      {
+        auto other = static_cast<GeometryFace*>(dst.primary);
+        if(dst.domin != other->domout && dst.domout != other->domin)
+          do_invert = true;
+      }
 
     // now insert mapped surface elements
     for(auto sei : mesh.SurfaceElements().Range())