Added method to access face normals.

opm/core/grid/GridHelpers.cpp

@@ -53,6 +53,11 @@ const double* faceCentroid(const UnstructuredGrid& grid, int face_index)
     return grid.face_centroids+face_index*grid.dimensions;
 }
 
+const double* faceNormal(const UnstructuredGrid& grid, int face_index)
+{
+    return grid.face_normals+face_index*grid.dimensions;
+}
+
 SparseTableView cell2Faces(const UnstructuredGrid& grid)
 {
     return SparseTableView(grid.cell_faces, grid.cell_facepos, numCells(grid));

opm/core/grid/GridHelpers.hpp

@@ -134,6 +134,12 @@ const double* beginFaceCentroids(const UnstructuredGrid& grid);
 /// \breif coordinate The coordinate index.
 const double* faceCentroid(const UnstructuredGrid& grid, int face_index);
 
+/// \brief Get the normal of a face.
+/// \param grid The grid that the face is part of.
+/// \param face_index The index of the face in the grid.
+const double* faceNormal(const UnstructuredGrid& grid, int face_index);
+
+
 /// \brief Maps the grid type to the associated type of the cell to faces mapping.
 ///
 /// Provides a type named Type.