Select Git revision
-
Christophe Geuzaine authored
in addition to the default camelCase function names, add snake case aliases in the Python and Julia API, as this is the recommended style in these languages
Christophe Geuzaine authoredin addition to the default camelCase function names, add snake case aliases in the Python and Julia API, as this is the recommended style in these languages
t3.cpp 5.80 KiB
// -----------------------------------------------------------------------------
//
// Gmsh C++ tutorial 3
//
// Extruded meshes, ONELAB parameters, options
//
// -----------------------------------------------------------------------------
#include <set>
#include <cmath>
#include <gmsh.h>
int main(int argc, char **argv)
{
gmsh::initialize(argc, argv);
auto createGeometryAndMesh = []()
{
// Clear all models and create a new one
gmsh::clear();
gmsh::model::add("t3");
// 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);
gmsh::model::geo::synchronize();
gmsh::model::addPhysicalGroup(1, {1, 2, 4}, 5);
gmsh::model::addPhysicalGroup(2, {1}, -1, "My surface");
// As in `t2.cpp', we plan to perform an extrusion along the z axis. But
// here, instead of only extruding the geometry, we also want to extrude the
// 2D mesh. This is done with the same `extrude()' function, but by
// specifying element 'Layers' (2 layers in this case, the first one with 8
// subdivisions and the second one with 2 subdivisions, both with a height
// of h/2). The number of elements for each layer and the (end) height of
// each layer are specified in two vectors:
double h = 0.1;
std::vector<std::pair<int, int> > ov;
gmsh::model::geo::extrude({{2, 1}}, 0, 0, h, ov, {8, 2}, {0.5, 1});
// The extrusion can also be performed with a rotation instead of a
// translation, and the resulting mesh can be recombined into prisms (we use
// only one layer here, with 7 subdivisions). All rotations are specified by
// an an axis point (-0.1, 0, 0.1), an axis direction (0, 1, 0), and a
// rotation angle (-Pi/2):
gmsh::model::geo::revolve({{2, 28}}, -0.1, 0, 0.1, 0, 1, 0, -M_PI / 2, ov,
{7});
// Using the built-in geometry kernel, only rotations with angles < Pi are
// supported. To do a full turn, you will thus need to apply at least 3
// rotations. The OpenCASCADE geometry kernel does not have this limitation.
// A translation (-2 * h, 0, 0) and a rotation ((0, 0.15, 0.25), (1, 0, 0),
// angle * Pi / 180) can also be combined to form a "twist". The last
// (optional) argument for the extrude() and twist() functions specifies
// whether the extruded mesh should be recombined or not. The `angle'
// parameter is retrieved from the ONELAB database (it can be set
// interactively in the GUI -- see below):
std::vector<double> angle;
gmsh::onelab::getNumber("Parameters/Twisting angle", angle);
gmsh::model::geo::twist({{2, 50}}, 0, 0.15, 0.25, -2 * h, 0, 0, 1, 0, 0,
angle[0] * M_PI / 180., ov, {10}, {}, true);
gmsh::model::geo::synchronize();
// All the extrusion functions return a vector of extruded entities: the
// "top" of the extruded surface (in `ov[0]'), the newly created volume (in
// `ov[1]') and the tags of the lateral surfaces (in `ov[2]', `ov[3]', ...).
// We can then define a new physical volume (with tag 101) to group all the
// elementary volumes:
gmsh::model::addPhysicalGroup(3, {1, 2, ov[1].second}, 101);
gmsh::model::mesh::generate(3);
gmsh::write("t3.msh");
};
// Let us now change some options... Since all interactive options are
// accessible through the API, we can for example make point tags visible or
// redefine some colors:
gmsh::option::setNumber("Geometry.PointNumbers", 1);
gmsh::option::setColor("Geometry.Color.Points", 255, 165, 0);
gmsh::option::setColor("General.Color.Text", 255, 255, 255);
gmsh::option::setColor("Mesh.Color.Points", 255, 0, 0);
// Note that for conciseness "Color." can be ommitted in color options:
int r, g, b, a;
gmsh::option::getColor("Geometry.Points", r, g, b, a);
gmsh::option::setColor("Geometry.Surfaces", r, g, b, a);
// We create a ONELAB parameter to define the angle of the twist. ONELAB
// parameters can be modified interactively in the GUI, and can be exchanged
// with other codes connected to the same ONELAB database. The database can be
// accessed through the Gmsh C++ API using JSON-formatted strings (see
// https://gitlab.onelab.info/doc/tutorials/-/wikis/ONELAB-JSON-interface for
// more information):
gmsh::onelab::set(R"( [
{
"type":"number",
"name":"Parameters/Twisting angle",
"values":[90],
"min":0,
"max":120,
"step":1
}
] )");
// Create the geometry and mesh it:
createGeometryAndMesh();
// Launch the GUI and handle the "check" event (recorded in the
// "ONELAB/Action" parameter) to recreate the geometry with a new twisting
// angle if necessary:
auto checkForEvent = [=]() -> bool {
std::vector<std::string> action;
gmsh::onelab::getString("ONELAB/Action", action);
if(action.size() && action[0] == "check") {
gmsh::onelab::setString("ONELAB/Action", {""});
createGeometryAndMesh();
gmsh::graphics::draw();
}
return true;
};
std::set<std::string> args(argv, argv + argc);
if(!args.count("-nopopup")) {
gmsh::fltk::initialize();
while(gmsh::fltk::isAvailable() && checkForEvent())
gmsh::fltk::wait();
}
// When the GUI is launched, you can use the `Help->Current Options and
// Workspace' menu to see the current values of all options. To save the
// options in a file, use `File->Export->Gmsh Options', or through the api:
// gmsh::write("t3.opt");
gmsh::finalize();
return 0;
}