From: Matthias Maier <tamiko@kyomu.43-1.org>
Date: Wed, 26 Nov 2014 23:51:46 +0000 (+0100)
Subject: Bugfix: adjust rotation for inverted matching
X-Git-Tag: v8.2.0-rc1~36^2~3
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4c5c033002a4f46bca2b65347c6a7bd6a970447f;p=dealii.git

Bugfix: adjust rotation for inverted matching

When constraining from face_1 to face_2 we have to use an (orientation,
flip, rotation) bitset that actually gives the relative orientation of
face_2 to face_1 (and not as specified face_1 to face_2).

This worked by accident because the constraining direction face_2 to face_1
is accidentally almost always used in all test cases.
---

diff --git a/source/dofs/dof_tools_constraints.cc b/source/dofs/dof_tools_constraints.cc
index 2d1f8f22b7..cf1832a494 100644
--- a/source/dofs/dof_tools_constraints.cc
+++ b/source/dofs/dof_tools_constraints.cc
@@ -2133,6 +2133,7 @@ namespace DoFTools
           {
             FullMatrix<double> inverse(transformation.m());
             inverse.invert(transformation);
+
             set_periodicity_constraints(face_2,
                                         face_1,
                                         inverse,
@@ -2146,13 +2147,22 @@ namespace DoFTools
           {
             Assert(!face_1->has_children(), ExcInternalError());
 
+            // Important note:
+            // In 3D we have to take care of the fact that face_rotation
+            // gives the relative rotation of face_1 to face_2, i.e. we
+            // have to invert the rotation when constraining face_2 to
+            // face_1. Therefore face_flip has to be toggled if
+            // face_rotation is true:
+            // In case of inverted orientation, nothing has to be done.
             set_periodicity_constraints(face_1,
                                         face_2,
                                         transformation,
                                         constraint_matrix,
                                         component_mask,
                                         face_orientation,
-                                        face_flip,
+                                        face_orientation
+                                          ? face_rotation ^ face_flip
+                                          : face_flip,
                                         face_rotation);
           }
       }