From: David Wells <drwells@email.unc.edu>
Date: Fri, 16 Apr 2021 17:03:17 +0000 (-0400)
Subject: Make the vertex swapping algorithm work with the new-style ordering.
X-Git-Tag: v9.3.0-rc1~216^2~2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7df92c7ab76f4fea69304b3df403d6afefe2b82c;p=dealii.git

Make the vertex swapping algorithm work with the new-style ordering.

This is necessary for the tecplot reader, which relies on this behavior.
---

diff --git a/source/grid/grid_reordering.cc b/source/grid/grid_reordering.cc
index 90f93551c6..922af99583 100644
--- a/source/grid/grid_reordering.cc
+++ b/source/grid/grid_reordering.cc
@@ -1179,7 +1179,10 @@ GridReordering<2>::invert_all_cells_of_negative_grid(
       if (GridTools::cell_measure<2>(all_vertices, vertices_lex) < 0)
         {
           ++n_negative_cells;
-          std::swap(cell.vertices[1], cell.vertices[3]);
+          if (use_new_style_ordering)
+            std::swap(cell.vertices[1], cell.vertices[2]);
+          else
+            std::swap(cell.vertices[1], cell.vertices[3]);
 
           // Check whether the resulting cell is now ok.
           // If not, then the grid is seriously broken and