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better growth vector computation for non orthogonal faces

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This commit is contained in:
Christopher Lackner 2023-02-13 12:04:30 +01:00
parent ecd077f154
commit 46d53168b8
1 changed files with 71 additions and 4 deletions
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71
libsrc/meshing/boundarylayer.cpp
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@ -669,15 +669,82 @@ namespace netgen
// combine normal vectors for each face to keep uniform distances
auto & np = growthvectors[pi];
for(auto & [facei, n] : normals)
ArrayMem<Vec<3>, 3> ns;
for (auto &[facei, n] : normals) {
ns.Append(n);
}
ArrayMem<Vec<3>, 3> removed;
// reduce to full rank of max 3
while(true)
{
if(np.Length() == 0) { np = n; continue; }
if(ns.Size() <= 1)
break;
if(ns.Size() == 2 && ns[0] * ns[1] < 1 - 1e-6)
break;
if (ns.Size() == 3)
{
DenseMatrix mat(3,3);
for(auto i : Range(3))
for(auto j : Range(3))
mat(i,j) = ns[i][j];
if(fabs(mat.Det()) > 1e-6)
break;
}
int maxpos1;
int maxpos2;
double val = 0;
for (auto i : Range(ns))
{
for (auto j : Range(i + 1, ns.Size()))
{
double ip = ns[i] * ns[j];
if(ip > val)
{
val = ip;
maxpos1 = i;
maxpos2 = j;
}
}
}
removed.Append(ns[maxpos1]);
removed.Append(ns[maxpos2]);
ns[maxpos1] = 0.5 * (ns[maxpos1] + ns[maxpos2]);
ns.DeleteElement(maxpos2);
}
if(ns.Size() == 0)
continue;
if(ns.Size() == 1)
np = ns[0];
else if(ns.Size() == 2)
{
np = ns[0];
auto n = ns[1];
auto npn = np * n;
auto npnp = np * np;
auto nn = n * n;
if(nn-npn*npn/npnp == 0) { np = n; continue; }
np += (nn - npn)/(nn - npn*npn/npnp) * (n - npn/npnp * np);
}
else // ns.Size() == 3
{
DenseMatrix mat(3,3);
for(auto i : Range(3))
for(auto j : Range(3))
mat(i, j) = ns[i] * ns[j];
Vector rhs(3);
rhs = 1.;
Vector res(3);
DenseMatrix inv(3, ns.Size());
CalcInverse(mat, inv);
inv.Mult(rhs, res);
for(auto i : Range(ns))
np += res[i] * ns[i];
}
for(auto& n : removed)
if(n * np < 0)
cout << "WARNING: Growth vector at point " << pi << " in opposite direction to face normal!" << endl << "Growthvector = " << np << ", face normal = " << n << endl;
}
}