Merge pull request #11572 from peterrum/simplex_get_position_vector

Generalize VectorTools::get_position_vector for simplex meshes

diff --cc include/deal.II/grid/reference_cell.h
Simple merge

diff --cc source/grid/reference_cell.cc
index 54ee83ba0a09283b34d91e204bd79c0977c94c32,68a599be18909b7d15905d02411b48887394dae0..8ae0afa4f4d0af99b1ed8084962d4f0581e9240a
--- 1/source/grid/reference_cell.cc
--- 2/source/grid/reference_cell.cc
+++ b/source/grid/reference_cell.cc
@@@ -105,7 -102,32 +105,33 @@@ namespace ReferenceCel
    }
  
  
 +
+   template <int dim, int spacedim>
+   std::unique_ptr<Mapping<dim, spacedim>>
+   get_default_mapping(const Type &reference_cell, const unsigned int degree)
+   {
+     AssertDimension(dim, get_dimension(reference_cell));
+ 
+     if (reference_cell == get_hypercube(dim))
+       return std::make_unique<MappingQGeneric<dim, spacedim>>(degree);
+     else if (reference_cell == Type::Tri || reference_cell == Type::Tet)
+       return std::make_unique<MappingFE<dim, spacedim>>(
+         Simplex::FE_P<dim, spacedim>(degree));
+     else if (reference_cell == Type::Pyramid)
+       return std::make_unique<MappingFE<dim, spacedim>>(
+         Simplex::FE_PyramidP<dim, spacedim>(degree));
+     else if (reference_cell == Type::Wedge)
+       return std::make_unique<MappingFE<dim, spacedim>>(
+         Simplex::FE_WedgeP<dim, spacedim>(degree));
+     else
+       {
+         Assert(false, ExcNotImplemented());
+       }
+ 
+     return std::make_unique<MappingQGeneric<dim, spacedim>>(degree);
+   }
+ 
+ 
    template <int dim, int spacedim>
    const Mapping<dim, spacedim> &
    get_default_linear_mapping(const Type &reference_cell)