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#include <gmsh.h>
#include <math.h>
void create_mesh(std::size_t N, std::vector<double> &coords,
std::vector<std::size_t> &nodes,
std::vector<std::size_t> &tris)
{
auto get_node_tag = [N](std::size_t i, std::size_t j) {
return (N + 1) * i + j + 1;
};
std::size_t k = 0, l = 0;
for(std::size_t i = 0; i < N + 1; i++) {
for(std::size_t j = 0; j < N + 1; j++) {
nodes[k] = get_node_tag(i, j);
coords[3 * k] = (double)i / N;
coords[3 * k + 1] = (double)j / N;
coords[3 * k + 2] = 0.05 * sin(10 * (double)(i + j) / N);
k++;
if(i > 0 && j > 0) {
tris[6 * l] = get_node_tag(i - 1, j - 1);
tris[6 * l + 1] = get_node_tag(i, j - 1);
tris[6 * l + 2] = get_node_tag(i - 1, j);
tris[6 * l + 3] = get_node_tag(i, j - 1);
tris[6 * l + 4] = get_node_tag(i, j);
tris[6 * l + 5] = get_node_tag(i - 1, j);
l++;
}
}
}
}
int main()
{
gmsh::initialize();
int N = 2500;
double tic = gmsh::logger::getWallTime();
// x, y, z coordinates of all the nodes
std::vector<double> coords((N + 1) * (N + 1) * 3);
// tags of corresponding nodes
std::vector<std::size_t> nodes((N + 1) * (N + 1));
// connectivities (node tags) of triangle elements
std::vector<std::size_t> tris(N * N * 2 * 3);
create_mesh(N, coords, nodes, tris);
double toc = gmsh::logger::getWallTime();
printf("==> created nodes and connectivities in %g seconds\n", toc - tic);
tic = gmsh::logger::getWallTime();
int surf = gmsh::model::addDiscreteEntity(2);
toc = gmsh::logger::getWallTime();
printf("==> created surface in %g seconds\n", toc - tic);
tic = gmsh::logger::getWallTime();
gmsh::model::mesh::addNodes(2, 1, nodes, coords);
toc = gmsh::logger::getWallTime();
printf("==> imported nodes in %g seconds\n", toc - tic);
tic = gmsh::logger::getWallTime();
gmsh::model::mesh::addElementsByType(1, 2, {}, tris);
toc = gmsh::logger::getWallTime();
printf("==> imported elements in %g seconds\n", toc - tic);
tic = gmsh::logger::getWallTime();
gmsh::option::setNumber("Mesh.Binary", 1);
gmsh::write("import_perf_cpp.msh");
toc = gmsh::logger::getWallTime();
printf("==> wrote to disk in %g seconds\n", toc - tic);
tic = gmsh::logger::getWallTime();
gmsh::merge("import_perf_cpp.msh");
toc = gmsh::logger::getWallTime();
printf("==> read from disk in %g seconds\n", toc - tic);
//gmsh::fltk::run();
gmsh::finalize();
return 0;
}
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