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// -----------------------------------------------------------------------------
//
// Gmsh C++ tutorial 4
//
// Holes in surfaces, annotations, entity colors
//
// -----------------------------------------------------------------------------
#include <set>
#include <cmath>
#include <gmsh.h>
double hypoth(double a, double b) { return sqrt(a * a + b * b); }
int main(int argc, char **argv)
{
gmsh::initialize(argc, argv);
gmsh::model::add("t4");
double cm = 1e-02;
double e1 = 4.5 * cm, e2 = 6 * cm / 2, e3 = 5 * cm / 2;
double h1 = 5 * cm, h2 = 10 * cm, h3 = 5 * cm, h4 = 2 * cm, h5 = 4.5 * cm;
double R1 = 1 * cm, R2 = 1.5 * cm, r = 1 * cm;
double Lc1 = 0.01;
double Lc2 = 0.003;
double ccos =
(-h5 * R1 + e2 * hypot(h5, hypot(e2, R1))) / (h5 * h5 + e2 * e2);
double ssin = sqrt(1 - ccos * ccos);
// We start by defining some points and some lines. To make the code shorter
// we can redefine a namespace:
namespace factory = gmsh::model::geo;
factory::addPoint(-e1 - e2, 0, 0, Lc1, 1);
factory::addPoint(-e1 - e2, h1, 0, Lc1, 2);
factory::addPoint(-e3 - r, h1, 0, Lc2, 3);
factory::addPoint(-e3 - r, h1 + r, 0, Lc2, 4);
factory::addPoint(-e3, h1 + r, 0, Lc2, 5);
factory::addPoint(-e3, h1 + h2, 0, Lc1, 6);
factory::addPoint(e3, h1 + h2, 0, Lc1, 7);
factory::addPoint(e3, h1 + r, 0, Lc2, 8);
factory::addPoint(e3 + r, h1 + r, 0, Lc2, 9);
factory::addPoint(e3 + r, h1, 0, Lc2, 10);
factory::addPoint(e1 + e2, h1, 0, Lc1, 11);
factory::addPoint(e1 + e2, 0, 0, Lc1, 12);
factory::addPoint(e2, 0, 0, Lc1, 13);
factory::addPoint(R1 / ssin, h5 + R1 * ccos, 0, Lc2, 14);
factory::addPoint(0, h5, 0, Lc2, 15);
factory::addPoint(-R1 / ssin, h5 + R1 * ccos, 0, Lc2, 16);
factory::addPoint(-e2, 0.0, 0, Lc1, 17);
factory::addPoint(-R2, h1 + h3, 0, Lc2, 18);
factory::addPoint(-R2, h1 + h3 + h4, 0, Lc2, 19);
factory::addPoint(0, h1 + h3 + h4, 0, Lc2, 20);
factory::addPoint(R2, h1 + h3 + h4, 0, Lc2, 21);
factory::addPoint(R2, h1 + h3, 0, Lc2, 22);
factory::addPoint(0, h1 + h3, 0, Lc2, 23);
factory::addPoint(0, h1 + h3 + h4 + R2, 0, Lc2, 24);
factory::addPoint(0, h1 + h3 - R2, 0, Lc2, 25);
factory::addLine(1, 17, 1);
factory::addLine(17, 16, 2);
// Gmsh provides other curve primitives than straight lines: splines,
// B-splines, circle arcs, ellipse arcs, etc. Here we define a new circle arc,
// starting at point 14 and ending at point 16, with the circle's center being
// the point 15:
factory::addCircleArc(14, 15, 16, 3);
// Note that, in Gmsh, circle arcs should always be smaller than Pi. The
// OpenCASCADE geometry kernel does not have this limitation.
// We can then define additional lines and circles, as well as a new surface:
factory::addLine(14, 13, 4);
factory::addLine(13, 12, 5);
factory::addLine(12, 11, 6);
factory::addLine(11, 10, 7);
factory::addCircleArc(8, 9, 10, 8);
factory::addLine(8, 7, 9);
factory::addLine(7, 6, 10);
factory::addLine(6, 5, 11);
factory::addCircleArc(3, 4, 5, 12);
factory::addLine(3, 2, 13);
factory::addLine(2, 1, 14);
factory::addLine(18, 19, 15);
factory::addCircleArc(21, 20, 24, 16);
factory::addCircleArc(24, 20, 19, 17);
factory::addCircleArc(18, 23, 25, 18);
factory::addCircleArc(25, 23, 22, 19);
factory::addLine(21, 22, 20);
factory::addCurveLoop({17, -15, 18, 19, -20, 16}, 21);
factory::addPlaneSurface({21}, 22);
// But we still need to define the exterior surface. Since this surface has a
// hole, its definition now requires two curves loops:
factory::addCurveLoop({11, -12, 13, 14, 1, 2, -3, 4, 5, 6, 7, -8, 9, 10}, 23);
factory::addPlaneSurface({23, 21}, 24);
// As a general rule, if a surface has N holes, it is defined by N+1 curve
// loops: the first loop defines the exterior boundary; the other loops define
// the boundaries of the holes.
factory::synchronize();
// Finally, we can add some comments by creating a post-processing view
// containing some strings:
int v = gmsh::view::add("comments");
// Add a text string in window coordinates, 10 pixels from the left and 10
// pixels from the bottom:
gmsh::view::addListDataString(v, {10, -10}, {"Created with Gmsh"});
// Add a text string in model coordinates centered at (X,Y,Z) = (0, 0.11, 0),
// with some style attributes:
gmsh::view::addListDataString(v, {0, 0.11, 0}, {"Hole"},
{"Align", "Center", "Font", "Helvetica"});
// If a string starts with `file://', the rest is interpreted as an image
// file. For 3D annotations, the size in model coordinates can be specified
// after a `@' symbol in the form `widthxheight' (if one of `width' or
// `height' is zero, natural scaling is used; if both are zero, original image
// dimensions in pixels are used):
gmsh::view::addListDataString(
v, {0, 0.09, 0}, {"file://../t4_image.png@0.01x0"}, {"Align", "Center"});
// The 3D orientation of the image can be specified by proving the direction
// of the bottom and left edge of the image in model space:
gmsh::view::addListDataString(v, {-0.01, 0.09, 0},
{"file://../t4_image.png@0.01x0,0,0,1,0,1,0"});
// The image can also be drawn in "billboard" mode, i.e. always parallel to
// the camera, by using the `#' symbol:
gmsh::view::addListDataString(
v, {0, 0.12, 0}, {"file://../t4_image.png@0.01x0#"}, {"Align", "Center"});
// The size of 2D annotations is given directly in pixels:
gmsh::view::addListDataString(v, {150, -7}, {"file://../t4_image.png@20x0"});
// These annotations are handled by a list-based post-processing view. For
// large post-processing datasets, that contain actual field values defined on
// a mesh, you should use model-based post-processing views instead, which
// allow to efficiently store continuous or discontinuous scalar, vector and
// tensor fields, or arbitrary polynomial order.
// Views and geometrical entities can be made to respond to double-click
// events, here to print some messages to the console:
gmsh::view::option::setString(v, "DoubleClickedCommand",
"Printf('View[0] has been double-clicked!');");
gmsh::option::setString("Geometry.DoubleClickedLineCommand",
"Printf('Curve %g has been double-clicked!', "
"Geometry.DoubleClickedEntityTag);");
// We can also change the color of some entities:
gmsh::model::setColor({{2, 22}}, 127, 127, 127); // Gray50
gmsh::model::setColor({{2, 24}}, 160, 32, 240); // Purple
for(int i = 1; i <= 14; i++)
gmsh::model::setColor({{1, i}}, 255, 0, 0); // Red
for(int i = 15; i <= 20; i++)
gmsh::model::setColor({{1, i}}, 255, 255, 0); // Yellow
gmsh::model::mesh::generate(2);
gmsh::write("t4.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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