From: Luca Heltai <luca.heltai@sissa.it>
Date: Sat, 12 Aug 2017 21:52:49 +0000 (-0600)
Subject: Get closest vertex to cell.
X-Git-Tag: v9.0.0-rc1~1252^2~2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eb0dd9604bcc9f74833b8485aa11dccbf235d4be;p=dealii.git

Get closest vertex to cell.
---

diff --git a/include/deal.II/grid/grid_tools.h b/include/deal.II/grid/grid_tools.h
index 1a2532d306..32d3bc5245 100644
--- a/include/deal.II/grid/grid_tools.h
+++ b/include/deal.II/grid/grid_tools.h
@@ -1023,6 +1023,20 @@ namespace GridTools
   std::vector<std::set<typename Triangulation<dim,spacedim>::active_cell_iterator> >
   vertex_to_cell_map(const Triangulation<dim,spacedim> &triangulation);
 
+  /**
+
+
+  /**
+   * Returns the local vertex index of cell @p cell that is closest to
+   * the given location @p position.
+   *
+   * @author Rene Gassmoeller, Luca Heltai, 2017.
+   */
+  template <int dim, int spacedim>
+  unsigned int
+  get_closest_vertex_of_cell(const typename Triangulation<dim,spacedim>::active_cell_iterator &cell,
+                             const Point<spacedim> &position);
+
   /**
    * Compute a globally unique index for each vertex and hanging node
    * associated with a locally owned active cell. The vertices of a ghost cell
diff --git a/source/grid/grid_tools.cc b/source/grid/grid_tools.cc
index 85a9194788..6c9e9d5a38 100644
--- a/source/grid/grid_tools.cc
+++ b/source/grid/grid_tools.cc
@@ -1460,6 +1460,28 @@ next_cell:
 
 
 
+  template <int dim, int spacedim>
+  unsigned int
+  get_closest_vertex_of_cell(const typename Triangulation<dim,spacedim>::active_cell_iterator &cell,
+                             const Point<spacedim> &position)
+  {
+    double minimum_distance = std::numeric_limits<double>::max();
+    unsigned int closest_vertex = numbers::invalid_unsigned_int;
+
+    for (unsigned int v=0; v<GeometryInfo<dim>::vertices_per_cell; ++v)
+      {
+        const double vertex_distance = position.distance(cell->vertex(v));
+        if (vertex_distance < minimum_distance)
+          {
+            closest_vertex = v;
+            minimum_distance = vertex_distance;
+          }
+      }
+    return closest_vertex;
+  }
+
+
+
   template <int dim, int spacedim>
   std::pair<typename hp::DoFHandler<dim,spacedim>::active_cell_iterator, Point<dim> >
   find_active_cell_around_point (const hp::MappingCollection<dim,spacedim>   &mapping,