opm-core/opm/core/grid/GridUtilities.cpp
2014-12-01 14:55:06 +01:00

130 lines
5.4 KiB
C++

/*
Copyright 2014 SINTEF ICT, Applied Mathematics.
This file is part of the Open Porous Media project (OPM).
OPM is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
OPM is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with OPM. If not, see <http://www.gnu.org/licenses/>.
*/
#include <opm/core/grid/GridUtilities.hpp>
#include <opm/core/grid/GridHelpers.hpp>
#include <boost/math/constants/constants.hpp>
#include <set>
#include <vector>
#include <cmath>
#include <algorithm>
namespace Opm
{
/// For each cell, find indices of all other cells sharing a vertex with it.
/// \param[in] grid A grid object.
/// \return A table of neighbour cell-indices by cell.
SparseTable<int> cellNeighboursAcrossVertices(const UnstructuredGrid& grid)
{
// 1. Create vertex->cell mapping. We do this by iterating
// over all faces, and adding both its cell neighbours
// to each of its vertices' data.
using namespace UgGridHelpers;
const int num_vertices = grid.number_of_nodes;
std::vector<std::set<int>> v2c(num_vertices);
const int num_faces = numFaces(grid);
const auto fc = faceCells(grid);
for (int face = 0; face < num_faces; ++face) {
for (int nodepos = grid.face_nodepos[face]; nodepos < grid.face_nodepos[face + 1]; ++nodepos) {
const int vertex = grid.face_nodes[nodepos];
for (int face_nb = 0; face_nb < 2; ++face_nb) {
const int face_nb_cell = fc(face, face_nb);
if (face_nb_cell >= 0) {
v2c[vertex].insert(face_nb_cell);
}
}
}
}
// 2. For each cell, iterate over its faces, iterate over
// their vertices, and collect all those vertices' cell
// neighbours. Add as row to sparse table.
SparseTable<int> cell_nb;
const int num_cells = numCells(grid);
const auto c2f = cell2Faces(grid);
// Reserve sufficient room for cartesian grids in 2 and 3
// dimensions. Note that this is not a limit, just an
// optimization similar to std::vector.
cell_nb.reserve(num_cells, (dimensions(grid) == 2 ? 8 : 26) * num_cells);
std::set<int> nb;
for (int cell = 0; cell < num_cells; ++cell) {
nb.clear();
const auto cell_faces = c2f[cell];
const int num_cell_faces = cell_faces.size();
for (int local_face = 0; local_face < num_cell_faces; ++local_face) {
const int face = cell_faces[local_face];
for (int nodepos = grid.face_nodepos[face]; nodepos < grid.face_nodepos[face + 1]; ++nodepos) {
const int vertex = grid.face_nodes[nodepos];
nb.insert(v2c[vertex].begin(), v2c[vertex].end());
}
}
nb.erase(cell);
cell_nb.appendRow(nb.begin(), nb.end());
}
// 3. Done. Return.
return cell_nb;
}
/// For each cell, order the (cell) neighbours counterclockwise.
/// \param[in] grid A 2d grid object.
/// \param[in, out] nb A cell-cell neighbourhood table, such as from cellNeighboursAcrossVertices().
void orderCounterClockwise(const UnstructuredGrid& grid,
SparseTable<int>& nb)
{
if (grid.dimensions != 2) {
OPM_THROW(std::logic_error, "Cannot use orderCounterClockwise in " << grid.dimensions << " dimensions.");
}
const int num_cells = grid.number_of_cells;
if (nb.size() != num_cells) {
OPM_THROW(std::logic_error, "Inconsistent arguments for orderCounterClockwise().");
}
// For each cell, compute each neighbour's angle with the x axis,
// sort that to find the correct permutation of the neighbours.
typedef std::pair<double, int> AngleAndPos;
std::vector<AngleAndPos> angle_and_pos;
std::vector<int> original;
for (int cell = 0; cell < num_cells; ++cell) {
const int num_nb = nb[cell].size();
angle_and_pos.clear();
angle_and_pos.resize(num_nb);
for (int ii = 0; ii < num_nb; ++ii) {
const int cell2 = nb[cell][ii];
const double v[2] = { grid.cell_centroids[2*cell2] - grid.cell_centroids[2*cell],
grid.cell_centroids[2*cell2 + 1] - grid.cell_centroids[2*cell + 1] };
// The formula below gives an angle in [0, 2*pi] with the positive x axis.
const double angle = boost::math::constants::pi<double>() - std::atan2(v[1], -v[0]);
angle_and_pos[ii] = std::make_pair(angle, ii);
}
original.assign(nb[cell].begin(), nb[cell].end());
std::sort(angle_and_pos.begin(), angle_and_pos.end());
for (int ii = 0; ii < num_nb; ++ii) {
nb[cell][ii] = original[angle_and_pos[ii].second];
}
}
}
} // namespace Opm