From: Peter Munch <peterrmuench@gmail.com>
Date: Fri, 5 Jun 2020 07:26:16 +0000 (+0200)
Subject: Simplify line_orientation()
X-Git-Tag: v9.3.0-rc1~1485^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=25bae99ce913a6ccd443e99d8bf46f4b89fea3cd;p=dealii.git

Simplify line_orientation()
---

diff --git a/include/deal.II/grid/tria_accessor.templates.h b/include/deal.II/grid/tria_accessor.templates.h
index bbd52503ee..20a7f6db38 100644
--- a/include/deal.II/grid/tria_accessor.templates.h
+++ b/include/deal.II/grid/tria_accessor.templates.h
@@ -753,71 +753,40 @@ namespace internal
       }
 
 
-      template <int dim, int spacedim>
+      template <int spacedim>
       inline static bool
-      line_orientation(const TriaAccessor<3, dim, spacedim> &accessor,
-                       const unsigned int                    line)
+      line_orientation(const TriaAccessor<3, 3, spacedim> &accessor,
+                       const unsigned int                  line)
       {
         Assert(accessor.used(), TriaAccessorExceptions::ExcCellNotUsed());
         AssertIndexRange(line, GeometryInfo<3>::lines_per_cell);
 
-        // get the line index by asking the
-        // quads. first assume standard orientation
-        //
-        // set up a table that for each
-        // line describes a) from which
-        // quad to take it, b) which line
-        // therein it is if the face is
-        // oriented correctly
-        static const unsigned int
-          lookup_table[GeometryInfo<3>::lines_per_cell][2] = {
-            {4, 0}, // take first four lines from bottom face
-            {4, 1},
-            {4, 2},
-            {4, 3},
-
-            {5, 0}, // second four lines from top face
-            {5, 1},
-            {5, 2},
-            {5, 3},
-
-            {0, 0}, // the rest randomly
-            {1, 0},
-            {0, 1},
-            {1, 1}};
-
-        const unsigned int quad_index     = lookup_table[line][0];
-        const unsigned int std_line_index = lookup_table[line][1];
-
-        const unsigned int line_index =
-          GeometryInfo<dim>::standard_to_real_face_line(
-            std_line_index,
-            accessor.face_orientation(quad_index),
-            accessor.face_flip(quad_index),
-            accessor.face_rotation(quad_index));
-
-        // now we got to the correct line and ask
-        // the quad for its line_orientation. however, if
-        // the face is rotated, it might be possible,
-        // that a standard orientation of the line
-        // with respect to the face corresponds to a
-        // non-standard orientation for the line with
+        const auto pair =
+          GeometryInfo<3>::standard_hex_line_to_quad_line_index(line);
+        const auto quad_index     = pair[0];
+        const auto std_line_index = pair[1];
+        const auto line_index     = GeometryInfo<3>::standard_to_real_face_line(
+          std_line_index,
+          accessor.face_orientation(quad_index),
+          accessor.face_flip(quad_index),
+          accessor.face_rotation(quad_index));
+
+        // now we got to the correct line and ask the quad for its
+        // line_orientation. however, if the face is rotated, it might be
+        // possible, that a standard orientation of the line with respect to
+        // the face corresponds to a non-standard orientation for the line with
         // respect to the cell.
         //
-        // set up a table indicating if the two
-        // standard orientations coincide
+        // set up a table indicating if the two standard orientations coincide
         //
-        // first index: two pairs of lines 0(lines
-        // 0/1) and 1(lines 2/3)
+        // first index: two pairs of lines 0(lines 0/1) and 1(lines 2/3)
         //
-        // second index: face_orientation; 0:
-        // opposite normal, 1: standard
+        // second index: face_orientation; 0: opposite normal, 1: standard
         //
-        // third index: face_flip; 0: standard, 1:
-        // face rotated by 180 degrees
+        // third index: face_flip; 0: standard, 1: face rotated by 180 degrees
         //
-        // forth index: face_rotation: 0: standard,
-        // 1: face rotated by 90 degrees
+        // forth index: face_rotation: 0: standard, 1: face rotated by 90
+        // degrees
 
         static const bool bool_table[2][2][2][2] = {
           {{{true, false},  // lines 0/1, face_orientation=false,