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// -----------------------------------------------------------------------------
//
// Gmsh C++ tutorial 6
//
// Transfinite meshes, deleting entities
//
// -----------------------------------------------------------------------------
#include <set>
#include <gmsh.h>
int main(int argc, char **argv)
{
gmsh::initialize();
gmsh::model::add("t2");
// Copied from `t1.cpp'...
double lc = 1e-2;
gmsh::model::geo::addPoint(0, 0, 0, lc, 1);
gmsh::model::geo::addPoint(.1, 0, 0, lc, 2);
gmsh::model::geo::addPoint(.1, .3, 0, lc, 3);
gmsh::model::geo::addPoint(0, .3, 0, lc, 4);
gmsh::model::geo::addLine(1, 2, 1);
gmsh::model::geo::addLine(3, 2, 2);
gmsh::model::geo::addLine(3, 4, 3);
gmsh::model::geo::addLine(4, 1, 4);
gmsh::model::geo::addCurveLoop({4, 1, -2, 3}, 1);
gmsh::model::geo::addPlaneSurface({1}, 1);
// Delete the surface and the left line, and replace the line with 3 new ones:
gmsh::model::geo::remove({{2, 1}, {1, 4}});
int p1 = gmsh::model::geo::addPoint(-0.05, 0.05, 0, lc);
int p2 = gmsh::model::geo::addPoint(-0.05, 0.1, 0, lc);
int l1 = gmsh::model::geo::addLine(1, p1);
int l2 = gmsh::model::geo::addLine(p1, p2);
int l3 = gmsh::model::geo::addLine(p2, 4);
// Create surface:
gmsh::model::geo::addCurveLoop({2, -1, l1, l2, l3, -3}, 2);
gmsh::model::geo::addPlaneSurface({-2}, 1);
// The `setTransfiniteCurve()' meshing constraints explicitly specifies the
// location of the nodes on the curve. For example, the following command
// forces 20 uniformly placed nodes on curve 2 (including the nodes on the two
// end points):
gmsh::model::geo::mesh::setTransfiniteCurve(2, 20);
// Let's put 20 points total on combination of curves `l1', `l2' and `l3'
// (beware that the points `p1' and `p2' are shared by the curves, so we do
// not create 6 + 6 + 10 = 22 nodes, but 20!)
gmsh::model::geo::mesh::setTransfiniteCurve(l1, 6);
gmsh::model::geo::mesh::setTransfiniteCurve(l2, 6);
gmsh::model::geo::mesh::setTransfiniteCurve(l3, 10);
// Finally, we put 30 nodes following a geometric progression on curve 1
// (reversed) and on curve 3: Put 30 points following a geometric progression
gmsh::model::geo::mesh::setTransfiniteCurve(1, 30, "Progression", -1.2);
gmsh::model::geo::mesh::setTransfiniteCurve(3, 30, "Progression", 1.2);
// The `setTransfiniteSurface()' meshing constraint uses a transfinite
// interpolation algorithm in the parametric plane of the surface to connect
// the nodes on the boundary using a structured grid. If the surface has more
// than 4 corner points, the corners of the transfinite interpolation have to
// be specified by hand:
gmsh::model::geo::mesh::setTransfiniteSurface(1, "Left", {1, 2, 3, 4});
// To create quadrangles instead of triangles, one can use the `setRecombine'
// constraint:
gmsh::model::geo::mesh::setRecombine(2, 1);
// When the surface has only 3 or 4 points on its boundary the list of corners
// can be omitted in the `setTransfiniteSurface()' call:
gmsh::model::geo::addPoint(0.2, 0.2, 0, 1.0, 7);
gmsh::model::geo::addPoint(0.2, 0.1, 0, 1.0, 8);
gmsh::model::geo::addPoint(0.25, 0.2, 0, 1.0, 9);
gmsh::model::geo::addPoint(0.3, 0.1, 0, 1.0, 10);
gmsh::model::geo::addLine(8, 10, 10);
gmsh::model::geo::addLine(10, 9, 11);
gmsh::model::geo::addLine(9, 7, 12);
gmsh::model::geo::addLine(7, 8, 13);
gmsh::model::geo::addCurveLoop({10, 11, 12, 13}, 14);
gmsh::model::geo::addPlaneSurface({14}, 15);
for(int i = 10; i <= 13; i++)
gmsh::model::geo::mesh::setTransfiniteCurve(i, 10);
gmsh::model::geo::mesh::setTransfiniteSurface(15);
// The way triangles are generated can be controlled by specifying "Left",
// "Right" or "Alternate" in `setTransfiniteSurface()'. Try e.g.
//
// gmsh::model::geo::mesh::setTransfiniteSurface(15, "Alternate");
// Finally we apply an elliptic smoother to the grid to have a more regular
// mesh:
gmsh::option::setNumber("Mesh.Smoothing", 100);
gmsh::model::geo::synchronize();
gmsh::model::mesh::generate(2);
gmsh::write("t6.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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