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/*************************************
* Write Gmsh file
* First issue the 04/26/2004 by Paul CARRICO (paul.carrico@free.fr)
* At the moment, the GMSH format is available for
* linear tetrahedron elements i.e. in 3D
* (based on Neutral Format)
*
* Second issue the 05/05/2004 by Paul CARRICO
* Thanks to Joachim Schoeberl for the correction of a minor bug
* the 2 initial Gmsh Format (i.e. volume format and surface format) are group together)
* in only one file
**************************************/
#include <mystdlib.h>
#include <myadt.hpp>
#include <linalg.hpp>
#include <csg.hpp>
#include <meshing.hpp>
#include "writeuser.hpp"
namespace netgen
{
extern MeshingParameters mparam;
/*
* GMSH mesh format
* points, elements, surface elements and physical entities
*/
void WriteGmshFormat (const Mesh & mesh,
const filesystem::path & filename)
{
ofstream outfile (filename);
outfile.precision(6);
outfile.setf (ios::fixed, ios::floatfield);
outfile.setf (ios::showpoint);
int np = mesh.GetNP(); /// number of point
int ne = mesh.GetNE(); /// number of element
int nse = mesh.GetNSE(); /// number of surface element (BC)
int i, j, k, l;
/*
* 3D section : Linear volume elements (only tetrahedra)
*/
if (ne > 0 && mesh.VolumeElement(1).GetNP() == 4)
{
cout << "Write GMSH Format \n";
cout << "The GMSH format is available for linear tetrahedron elements only in 3D\n" << endl;
int inverttets = mparam.inverttets;
int invertsurf = mparam.inverttrigs;
/// Write nodes
outfile << "$NOD\n";
outfile << np << "\n";
for (i = 1; i <= np; i++)
{
const Point3d & p = mesh.Point(i);
outfile << i << " "; /// node number
outfile << p.X() << " ";
outfile << p.Y() << " ";
outfile << p.Z() << "\n";
}
outfile << "$ENDNOD\n";
/// write elements
outfile << "$ELM\n";
outfile << ne + nse << "\n"; //// number of elements + number of surfaces BC
for (i = 1; i <= nse; i++)
{
Element2d el = mesh.SurfaceElement(i);
if (invertsurf) el.Invert();
outfile << i;
outfile << " ";
outfile << "2";
outfile << " ";
outfile << mesh.GetFaceDescriptor (el.GetIndex()).BCProperty() << " ";
/// that means that physical entity = elementary entity (arbitrary approach)
outfile << mesh.GetFaceDescriptor (el.GetIndex()).BCProperty() << " ";
outfile << "3";
outfile << " ";
for (j = 1; j <= el.GetNP(); j++)
{
outfile << " ";
outfile << el.PNum(j);
}
outfile << "\n";
}
for (i = 1; i <= ne; i++)
{
Element el = mesh.VolumeElement(i);
if (inverttets) el.Invert();
outfile << nse + i; /// element number
outfile << " ";
outfile << "4"; /// element type i.e. Tetraedron == 4
outfile << " ";
outfile << 100000 + el.GetIndex();
/// that means that physical entity = elementary entity (arbitrary approach)
outfile << " ";
outfile << 100000 + el.GetIndex(); /// volume number
outfile << " ";
outfile << "4"; /// number of nodes i.e. 4 for a tetrahedron
for (j = 1; j <= el.GetNP(); j++)
{
outfile << " ";
outfile << el.PNum(j);
}
outfile << "\n";
}
outfile << "$ENDELM\n";
}
/*
* End of 3D section
*/
/*
* 2D section : available for triangles and quadrangles
*/
else if (ne == 0) /// means that there's no 3D element
{
cout << "\n Write Gmsh Surface Mesh (triangle and/or quadrangles)" << endl;
/// Write nodes
outfile << "$NOD\n";
outfile << np << "\n";
for (i = 1; i <= np; i++)
{
const Point3d & p = mesh.Point(i);
outfile << i << " "; /// node number
outfile << p.X() << " ";
outfile << p.Y() << " ";
outfile << p.Z() << "\n";
}
outfile << "$ENDNOD\n";
/// write triangles & quadrangles
outfile << "$ELM\n";
outfile << nse << "\n";
for (k = 1; k <= nse; k++)
{
const Element2d & el = mesh.SurfaceElement(k);
outfile << k;
outfile << " ";
outfile << (el.GetNP()-1); // 2 for a triangle and 3 for a quadrangle
outfile << " ";
outfile << mesh.GetFaceDescriptor (el.GetIndex()).BCProperty() << " ";
/// that means that physical entity = elementary entity (arbitrary approach)
outfile << mesh.GetFaceDescriptor (el.GetIndex()).BCProperty() << " ";
outfile << (el.GetNP()); // number of node per surfacic element
outfile << " ";
for (l = 1; l <= el.GetNP(); l++)
{
outfile << " ";
outfile << el.PNum(l);
}
outfile << "\n";
}
outfile << "$ENDELM$ \n";
}
/*
* End of 2D section
*/
else
{
cout << " Invalid element type for Gmsh volume Format !\n";
}
}
static RegisterUserFormat reg_gmsh ("Gmsh Format", {".gmsh"}, nullopt, WriteGmshFormat);
}
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