Added short description of manifold indicators

git-svn-id: https://svn.dealii.org/branches/branch_manifold_id@31727 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/doc/doxygen/headers/glossary.h b/deal.II/doc/doxygen/headers/glossary.h
index a4acb8b8c6ce7e928c106809f69a11ddcdb2e6f1..ae354e18fabf783d5fbf63d0eb6e7d89b6e7313e 100644 (file)
--- a/deal.II/doc/doxygen/headers/glossary.h
+++ b/deal.II/doc/doxygen/headers/glossary.h
@@ -378,6 +378,51 @@
  *
  * @see @ref boundary "The module on boundaries"
  *
+ * <dt class="glossary">@anchor GlossManifoldIndicator <b>%Manifold indicator</b></dt>
+ *
+ * <dd> Every object that makes up a Triangulation (cells, faces,
+ * edges, etc.), is associated with a unique number (of type
+ * types::manifol_id) that is used to identify which manifold object
+ * is responsible to generate new points when the mesh is refined. 
+ *
+ * By default, all manifold indicators of a mesh are set to
+ * types::invalid_manifold_id. A typical piece of code that sets the
+ * manifold indicator on a object to something else would look like
+ * this, here setting the manifold indicator to 42 for all cells whose
+ * center has the x component located at $-1$:
+ *
+ * @code
+ * for (typename Triangulation<dim>::active_cell_iterator cell =
+ *     triangulation.begin_active();
+ *     cell != triangulation.end(); ++cell)
+ *             if (cell->center()[0] == -1)
+ *                     cell->set_manifold_id (42);
+ * @endcode
+ *
+ * Here we call the function TriaAccessor::set_manifold_id. It may
+ * also be appropriate to call TriaAccessor::set_all_manifold_ids
+ * instead, to set recursively the manifold id on each face (and edge,
+ * if in 3d). To query the manifold indicator of a particular object
+ * edge, use TriaAccessor::manifold_id.
+ *
+ * The code above only sets the manifold indicators of a particular
+ * part of the Triangulation, but it does not by itself change the way
+ * the Triangulation class treats this object for the purposes of mesh
+ * refinement. For this, you need to call Triangulation::set_manifold
+ * to associate a manifold object with a particular manifold
+ * indicator. This allows the Triangulation objects to use a different
+ * method of finding new points on cells, faces or edges to be
+ * refined; the default is to use a FlatManifold object for all faces
+ * and edges.
+ *
+ * @note Manifold indicators are inherited from parents to their
+ * children upon mesh refinement. Some more information about manifold
+ * indicators is also presented in a section of the documentation of
+ * the Triangulation class.
+ * </dd>
+ *
+ * @see @ref manifold "The module on Manifolds"
+ *
  *
  * <dt class="glossary">@anchor GlossComponent <b>Component</b></dt>
  *