/usr/include/dune/grid/utility/structuredgridfactory.hh is in libdune-grid-dev 2.5.1-1.
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// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_STRUCTURED_GRID_FACTORY_HH
#define DUNE_STRUCTURED_GRID_FACTORY_HH
/** \file
\brief A class to construct structured cube and simplex grids using the grid factory
*/
#include <algorithm>
#include <array>
#include <cstddef>
#include <cstdlib>
#include <memory>
#include <dune/common/classname.hh>
#include <dune/common/exceptions.hh>
#include <dune/common/fvector.hh>
#include <dune/common/parallel/mpihelper.hh>
#include <dune/grid/common/gridfactory.hh>
#include <dune/grid/utility/multiindex.hh>
namespace Dune {
/** \brief Construct structured cube and simplex grids in unstructured grid managers
*/
template <class GridType>
class StructuredGridFactory
{
typedef typename GridType::ctype ctype;
static const int dim = GridType::dimension;
static const int dimworld = GridType::dimensionworld;
/** \brief Insert a structured set of vertices into the factory */
static void insertVertices(GridFactory<GridType>& factory,
const FieldVector<ctype,dimworld>& lowerLeft,
const FieldVector<ctype,dimworld>& upperRight,
const std::array<unsigned int,dim>& vertices)
{
FactoryUtilities::MultiIndex<dim> index(vertices);
// Compute the total number of vertices to be created
int numVertices = index.cycle();
// Create vertices
for (int i=0; i<numVertices; i++, ++index) {
// scale the multiindex to obtain a world position
FieldVector<double,dimworld> pos(0);
for (int j=0; j<dim; j++)
pos[j] = lowerLeft[j] + index[j] * (upperRight[j]-lowerLeft[j])/(vertices[j]-1);
for (int j=dim; j<dimworld; j++)
pos[j] = lowerLeft[j];
factory.insertVertex(pos);
}
}
// Compute the index offsets needed to move to the adjacent vertices
// in the different coordinate directions
static std::array<unsigned int, dim> computeUnitOffsets(const std::array<unsigned int,dim>& vertices)
{
std::array<unsigned int, dim> unitOffsets;
if (dim>0) // paranoia
unitOffsets[0] = 1;
for (int i=1; i<dim; i++)
unitOffsets[i] = unitOffsets[i-1] * vertices[i-1];
return unitOffsets;
}
public:
/** \brief Create a structured cube grid
If the grid dimension is less than the world dimension, the coefficients (dim+1,...,dimworld) in
the vertex coordinates are set to the corresponding values of the lowerLeft input argument.
\param lowerLeft Lower left corner of the grid
\param upperRight Upper right corner of the grid
\param elements Number of elements in each coordinate direction
*/
static std::shared_ptr<GridType> createCubeGrid(const FieldVector<ctype,dimworld>& lowerLeft,
const FieldVector<ctype,dimworld>& upperRight,
const std::array<unsigned int,dim>& elements)
{
// The grid factory
GridFactory<GridType> factory;
if (MPIHelper::getCollectiveCommunication().rank() == 0)
{
// Insert uniformly spaced vertices
std::array<unsigned int,dim> vertices = elements;
for( size_t i = 0; i < vertices.size(); ++i )
vertices[i]++;
// Insert vertices for structured grid into the factory
insertVertices(factory, lowerLeft, upperRight, vertices);
// Compute the index offsets needed to move to the adjacent
// vertices in the different coordinate directions
std::array<unsigned int, dim> unitOffsets =
computeUnitOffsets(vertices);
// Compute an element template (the cube at (0,...,0). All
// other cubes are constructed by moving this template around
unsigned int nCorners = 1<<dim;
std::vector<unsigned int> cornersTemplate(nCorners,0);
for (size_t i=0; i<nCorners; i++)
for (int j=0; j<dim; j++)
if ( i & (1<<j) )
cornersTemplate[i] += unitOffsets[j];
// Insert elements
FactoryUtilities::MultiIndex<dim> index(elements);
// Compute the total number of elementss to be created
int numElements = index.cycle();
for (int i=0; i<numElements; i++, ++index) {
// 'base' is the index of the lower left element corner
unsigned int base = 0;
for (int j=0; j<dim; j++)
base += index[j] * unitOffsets[j];
// insert new element
std::vector<unsigned int> corners = cornersTemplate;
for (size_t j=0; j<corners.size(); j++)
corners[j] += base;
factory.insertElement
(GeometryType(GeometryType::cube, dim), corners);
}
} // if(rank == 0)
// Create the grid and hand it to the calling method
return std::shared_ptr<GridType>(factory.createGrid());
}
/** \brief Create a structured simplex grid
This works in all dimensions. The Coxeter-Freudenthal-Kuhn triangulation is
used, which splits each cube into dim! (i.e., dim faculty) simplices. See Allgower and Georg,
'Numerical Path Following' for a description.
If the grid dimension is less than the world dimension, the coefficients (dim+1,...,dimworld) in
the vertex coordinates are set to the corresponding values of the lowerLeft input argument.
\param lowerLeft Lower left corner of the grid
\param upperRight Upper right corner of the grid
\param elements Number of elements in each coordinate direction
*/
static std::shared_ptr<GridType> createSimplexGrid(const FieldVector<ctype,dimworld>& lowerLeft,
const FieldVector<ctype,dimworld>& upperRight,
const std::array<unsigned int,dim>& elements)
{
// The grid factory
GridFactory<GridType> factory;
if(MPIHelper::getCollectiveCommunication().rank() == 0)
{
// Insert uniformly spaced vertices
std::array<unsigned int,dim> vertices = elements;
for (std::size_t i=0; i<vertices.size(); i++)
vertices[i]++;
insertVertices(factory, lowerLeft, upperRight, vertices);
// Compute the index offsets needed to move to the adjacent
// vertices in the different coordinate directions
std::array<unsigned int, dim> unitOffsets =
computeUnitOffsets(vertices);
// Loop over all "cubes", and split up each cube into dim!
// (factorial) simplices
FactoryUtilities::MultiIndex<dim> elementsIndex(elements);
size_t cycle = elementsIndex.cycle();
for (size_t i=0; i<cycle; ++elementsIndex, i++) {
// 'base' is the index of the lower left element corner
unsigned int base = 0;
for (int j=0; j<dim; j++)
base += elementsIndex[j] * unitOffsets[j];
// each permutation of the unit vectors gives a simplex.
std::vector<unsigned int> permutation(dim);
for (int j=0; j<dim; j++)
permutation[j] = j;
do {
// Make a simplex
std::vector<unsigned int> corners(dim+1);
corners[0] = base;
for (int j=0; j<dim; j++)
corners[j+1] =
corners[j] + unitOffsets[permutation[j]];
factory.insertElement
(GeometryType(GeometryType::simplex, dim),
corners);
} while (std::next_permutation(permutation.begin(),
permutation.end()));
}
} // if(rank == 0)
// Create the grid and hand it to the calling method
return std::shared_ptr<GridType>(factory.createGrid());
}
};
} // namespace Dune
#endif
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