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New function Mesh::FindIllegalTrigs()

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Find illegal trigs after surface meshing and use this information in
surface mesh optimization
This commit is contained in:
Matthias Hochsteger 2019-09-30 14:19:12 +02:00
parent 4987d12556
commit 8defe2f864
5 changed files with 50 additions and 18 deletions
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2
libsrc/csg/genmesh.cpp
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@ -504,6 +504,8 @@ namespace netgen
for (SurfaceElementIndex sei = oldnf; sei < mesh.GetNSE(); sei++)
mesh[sei].SetIndex (k);
auto n_illegal_trigs = mesh.FindIllegalTrigs();
PrintMessage (3, n_illegal_trigs, " illegal triangles");
// mesh.CalcSurfacesOfNode();

56
libsrc/meshing/meshclass.cpp
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@ -3689,31 +3689,51 @@ namespace netgen
return 0;
}
int Mesh :: FindIllegalTrigs ()
{
// Temporary table to store the vertex numbers of all triangles
INDEX_3_CLOSED_HASHTABLE<int> temp_tab(3*GetNSE() + 1);
size_t cnt = 0;
for (SurfaceElementIndex sei = 0; sei < GetNSE(); sei++)
{
const Element2d & sel = surfelements[sei];
if (sel.IsDeleted()) continue;
INDEX_3 i3(sel[0], sel[1], sel[2]);
i3.Sort();
if(temp_tab.Used(i3))
{
temp_tab.Set (i3, -1);
cnt++;
}
else
{
temp_tab.Set (i3, sei);
}
}
illegal_trigs = make_unique<INDEX_3_CLOSED_HASHTABLE<int>> (2*cnt+1);
for (SurfaceElementIndex sei = 0; sei < GetNSE(); sei++)
{
const Element2d & sel = surfelements[sei];
if (sel.IsDeleted()) continue;
INDEX_3 i3(sel[0], sel[1], sel[2]);
i3.Sort();
if(temp_tab.Get(i3)==-1)
illegal_trigs -> Set (i3, 1);
}
return cnt;
}
bool Mesh :: LegalTrig (const Element2d & el) const
{
// Search for surface trigs with same vertices ( may happen for instance with close surfaces in stl geometies )
if(!illegal_trigs)
{
auto & tab = const_cast<decltype(illegal_trigs)&>(illegal_trigs);
tab = make_unique<INDEX_3_CLOSED_HASHTABLE<int>> (3*GetNSE() + 1);
for (SurfaceElementIndex sei = 0; sei < GetNSE(); sei++)
{
const Element2d & sel = surfelements[sei];
if (sel.IsDeleted()) continue;
INDEX_3 i3(sel[0], sel[1], sel[2]);
i3.Sort();
if(tab->Used(i3) && tab->Get(i3)!=sei)
tab -> Set (i3, -1);
else
tab -> Set (i3, sei);
}
}
throw Exception("In Mesh::LegalTrig() - illegal_trigs table not built");
INDEX_3 i3 (el[0], el[1], el[2]);
i3.Sort();
if(illegal_trigs->Used(i3) && illegal_trigs->Get(i3)==-1)
if(illegal_trigs->Used(i3))
return false;
return 1;

4
libsrc/meshing/meshclass.hpp
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@ -571,6 +571,10 @@ namespace netgen
///
// Find trigs with same vertices
// return: number of illegal trigs
int FindIllegalTrigs ();
bool LegalTrig (const Element2d & el) const;
/**
if values non-null, return values in 4-double array:

3
libsrc/occ/occgenmesh.cpp
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@ -862,6 +862,9 @@ namespace netgen
for (SurfaceElementIndex sei = oldnf; sei < mesh.GetNSE(); sei++)
mesh[sei].SetIndex (k);
auto n_illegal_trigs = mesh.FindIllegalTrigs();
PrintMessage (3, n_illegal_trigs, " illegal triangles");
}
// ofstream problemfile("occmesh.rep");

3
libsrc/stlgeom/meshstlsurface.cpp
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@ -279,6 +279,9 @@ int STLSurfaceMeshing (STLGeometry & geom, class Mesh & mesh, const MeshingParam
mesh.FindOpenSegments();
nopen = mesh.GetNOpenSegments();
auto n_illegal_trigs = mesh.FindIllegalTrigs();
PrintMessage (3, n_illegal_trigs, " illegal triangles");
if (nopen)
{
geom.ClearMarkedSegs();