From a057e4e38c3625a120fa4ae42addb86eb00ee443 Mon Sep 17 00:00:00 2001
From: pauletti <pauletti@0785d39b-7218-0410-832d-ea1e28bc413d>
Date: Thu, 9 Dec 2010 17:06:19 +0000
Subject: [PATCH] FEValues with mapping Q1, now uses direction_flag to return
 the oriented normal for meshes of dim<spacedim

git-svn-id: https://svn.dealii.org/trunk@22951 0785d39b-7218-0410-832d-ea1e28bc413d
---
 deal.II/include/deal.II/fe/fe_update_flags.h |  4 +-
 deal.II/source/fe/fe_values.cc               |  6 ++
 deal.II/source/fe/mapping_q1.cc              | 85 +++++++++++---------
 3 files changed, 57 insertions(+), 38 deletions(-)

diff --git a/deal.II/include/deal.II/fe/fe_update_flags.h b/deal.II/include/deal.II/fe/fe_update_flags.h
index eabd2e4e9e..e292ac9795 100644
--- a/deal.II/include/deal.II/fe/fe_update_flags.h
+++ b/deal.II/include/deal.II/fe/fe_update_flags.h
@@ -340,7 +340,8 @@ operator &= (UpdateFlags &f1, UpdateFlags f2)
  * to the previously visited cell. This information is used for reusing data
  * when calling the method FEValues::reinit() (like derivatives, which do
  * not change if one cell is just a translation of the previous). Currently,
- * this variable does only recognize a translation. However, this concept
+ * this variable does only recognize a translation and a inverted traslation
+ * (if dim<spacedim). However, this concept
  * makes it easy to add additional staties to be detected in
  * FEValues/FEFaceValues for making use of these similarities as well.
  */
@@ -350,6 +351,7 @@ namespace CellSimilarity
     {
       none, 
       translation,
+      inverted_translation,
       invalid_next_cell
     };
 }
diff --git a/deal.II/source/fe/fe_values.cc b/deal.II/source/fe/fe_values.cc
index d09ea748bd..c5f3a2a6a9 100644
--- a/deal.II/source/fe/fe_values.cc
+++ b/deal.II/source/fe/fe_values.cc
@@ -3263,6 +3263,12 @@ FEValuesBase<dim,spacedim>::check_cell_similarity
 			 :
 			 CellSimilarity::none);
 
+  if ( (dim<spacedim) &&  (cell_similarity == CellSimilarity::translation) ) {
+    if (static_cast<const typename Triangulation<dim,spacedim>::cell_iterator &>
+	(*this->present_cell)->direction_flag()
+	!= cell->direction_flag() )
+      cell_similarity =  CellSimilarity::inverted_translation;
+  }
 				   // TODO: here, one could implement other
 				   // checks for similarity, e.g. for
 				   // children of a parallelogram.
diff --git a/deal.II/source/fe/mapping_q1.cc b/deal.II/source/fe/mapping_q1.cc
index a842c3ecc7..5f13f7f0ad 100644
--- a/deal.II/source/fe/mapping_q1.cc
+++ b/deal.II/source/fe/mapping_q1.cc
@@ -774,49 +774,60 @@ MappingQ1<dim,spacedim>::fill_fe_values (
 	     ExcDimensionMismatch(normal_vectors.size(), n_q_points));
 
       if (cell_similarity != CellSimilarity::translation)
-	for (unsigned int point=0; point<n_q_points; ++point)
-	  {
-
-	    if (dim==spacedim)
-	      JxW_values[point]
-		= determinant(data.contravariant[point])*weights[point];
-	    else if ( (dim==1) && (spacedim==2) )
-	      {
-   	        data.contravariant[point]=transpose(data.contravariant[point]);
+	for (unsigned int point=0; point<n_q_points; ++point) {
+
+	  if (dim==spacedim)
+	    JxW_values[point]
+	      = determinant(data.contravariant[point])*weights[point];
+	    
+	  else {
+	    if (cell_similarity == CellSimilarity::inverted_translation) {
+	      // we only need to flip the normal
+	      if(update_flags & update_normal_vectors)
+		normal_vectors[point] *= -1.;
+	    }
+	    else { 
+	      if ( (dim==1) && (spacedim==2) ) {
+		data.contravariant[point]=transpose(data.contravariant[point]);
 		JxW_values[point]
 		  = data.contravariant[point][0].norm()*weights[point];
-		if(update_flags & update_normal_vectors)
-		  {
-		    normal_vectors[point][0]
-		      = -(data.contravariant[point][0][1]
-			  /
-			  data.contravariant[point][0].norm());
-		    normal_vectors[point][1]
-		      = (data.contravariant[point][0][0]
-			 /
-			 data.contravariant[point][0].norm());
-		  }
+		if(update_flags & update_normal_vectors) {
+		  normal_vectors[point][0]
+		    = -(data.contravariant[point][0][1]
+			/
+			data.contravariant[point][0].norm());
+		  normal_vectors[point][1]
+		    = (data.contravariant[point][0][0]
+		       /
+		       data.contravariant[point][0].norm());
+		  if (!cell->direction_flag())
+		    normal_vectors[point] *= -1.;
+		}
 	      }
-	    else if ( (dim==2) && (spacedim==3) )
-	      {
-		data.contravariant[point]=transpose(data.contravariant[point]);
-		cross_product(data.contravariant[point][2],
-			      data.contravariant[point][0],
-			      data.contravariant[point][1]);
-		JxW_values[point]
-		  = data.contravariant[point][2].norm()*weights[point];
-		                          //the cell normal vector
-		                          //(normal to the surface)
-                                          //is stored in the 3d
-		                          //subtensor of the contravariant tensor
-		data.contravariant[point][2] /= data.contravariant[point][2].norm();
-		if(update_flags & update_normal_vectors)
-		  normal_vectors[point]=data.contravariant[point][2];
+	      else { 
+		if ( (dim==2) && (spacedim==3) ) {
+		  data.contravariant[point]=transpose(data.contravariant[point]);
+		  cross_product(data.contravariant[point][2],
+				data.contravariant[point][0],
+				data.contravariant[point][1]);
+		  JxW_values[point]
+		    = data.contravariant[point][2].norm()*weights[point];
+		  //the cell normal vector
+		  //(normal to the surface)
+		  //is stored in the 3d
+		  //subtensor of the contravariant tensor
+		  data.contravariant[point][2] /= data.contravariant[point][2].norm();
+		  if(update_flags & update_normal_vectors){
+		    normal_vectors[point]=data.contravariant[point][2];
+		    if (!cell->direction_flag())
+		      normal_vectors[point] *= -1.;
+		  }
+		}
 	      }
-
+	    }
 	  }
+	}
     }
-
 				   // copy values from InternalData to vector
 				   // given by reference
   if (update_flags & update_jacobians)
-- 
2.39.5