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// -----------------------------------------------------------------------------
//
// Gmsh C++ tutorial 19
//
// Thrusections, fillets, pipes, mesh size from curvature
//
// -----------------------------------------------------------------------------
// The OpenCASCADE geometry kernel supports several useful features for solid
// modelling.
#include <set>
#include <cmath>
#include <cstdlib>
#include <gmsh.h>
int main(int argc, char **argv)
{
gmsh::initialize(argc, argv);
gmsh::model::add("t19");
// Volumes can be constructed from (closed) curve loops thanks to the
// `addThruSections()' function
gmsh::model::occ::addCircle(0, 0, 0, 0.5, 1);
gmsh::model::occ::addCurveLoop({1}, 1);
gmsh::model::occ::addCircle(0.1, 0.05, 1, 0.1, 2);
gmsh::model::occ::addCurveLoop({2}, 2);
gmsh::model::occ::addCircle(-0.1, -0.1, 2, 0.3, 3);
gmsh::model::occ::addCurveLoop({3}, 3);
std::vector<std::pair<int, int> > out;
gmsh::model::occ::addThruSections({1, 2, 3}, out, 1);
gmsh::model::occ::synchronize();
// We can also force the creation of ruled surfaces:
gmsh::model::occ::addCircle(2 + 0, 0, 0, 0.5, 11);
gmsh::model::occ::addCurveLoop({11}, 11);
gmsh::model::occ::addCircle(2 + 0.1, 0.05, 1, 0.1, 12);
gmsh::model::occ::addCurveLoop({12}, 12);
gmsh::model::occ::addCircle(2 - 0.1, -0.1, 2, 0.3, 13);
gmsh::model::occ::addCurveLoop({13}, 13);
gmsh::model::occ::addThruSections({11, 12, 13}, out, 11, true, true);
gmsh::model::occ::synchronize();
// We copy the first volume, and fillet all its edges:
gmsh::model::occ::copy({{3, 1}}, out);
gmsh::model::occ::translate(out, 4, 0, 0);
gmsh::model::occ::synchronize();
std::vector<std::pair<int, int> > f;
gmsh::model::getBoundary(out, f);
std::vector<std::pair<int, int> > e;
gmsh::model::getBoundary(f, e, false);
std::vector<int> c;
for(auto i : e) c.push_back(abs(i.second));
gmsh::model::occ::fillet({out[0].second}, c, {0.1}, out);
gmsh::model::occ::synchronize();
// OpenCASCADE also allows general extrusions along a smooth path. Let's first
// define a spline curve:
double nturns = 1;
int npts = 20;
double r = 1;
double h = 1 * nturns;
std::vector<int> p;
for(int i = 0; i < npts; i++) {
double theta = i * 2 * M_PI * nturns / npts;
gmsh::model::occ::addPoint(r * cos(theta), r * sin(theta), i * h / npts, 1,
1000 + i);
p.push_back(1000 + i);
}
gmsh::model::occ::addSpline(p, 1000);
// A wire is like a curve loop, but open:
gmsh::model::occ::addWire({1000}, 1000);
// We define the shape we would like to extrude along the spline (a disk):
gmsh::model::occ::addDisk(1, 0, 0, 0.2, 0.2, 1000);
gmsh::model::occ::rotate({{2, 1000}}, 0, 0, 0, 1, 0, 0, M_PI / 2);
// We extrude the disk along the spline to create a pipe (other sweeping types
// can be specified; try e.g. "Frenet" instead of "DiscreteTrihedron"):
gmsh::model::occ::addPipe({{2, 1000}}, 1000, out, "DiscreteTrihedron");
// We delete the source surface, and increase the number of sub-edges for a
// nicer display of the geometry:
gmsh::model::occ::remove({{2, 1000}});
gmsh::option::setNumber("Geometry.NumSubEdges", 1000);
gmsh::model::occ::synchronize();
// We can activate the calculation of mesh element sizes based on curvature
// (here with a target of 20 elements per 2*Pi radians):
gmsh::option::setNumber("Mesh.MeshSizeFromCurvature", 20);
// We can constraint the min and max element sizes to stay within reasonnable
// values (see `t10.cpp' for more details):
gmsh::option::setNumber("Mesh.MeshSizeMin", 0.001);
gmsh::option::setNumber("Mesh.MeshSizeMax", 0.3);
gmsh::model::mesh::generate(3);
gmsh::write("t19.msh");
// Launch the GUI to see the results:
std::set<std::string> args(argv, argv + argc);
if(!args.count("-nopopup")) gmsh::fltk::run();
gmsh::finalize();
return 0;
}
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