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improve robustness for revolution surface meshing (FindSpecialPoints)

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This commit is contained in:
Joachim Schöberl 2020-10-11 13:26:34 +02:00
parent b5a9580a8e
commit b81f7f5ada
4 changed files with 123 additions and 9 deletions
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22
libsrc/csg/revolution.cpp
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@ -670,6 +670,23 @@ namespace netgen
surfaceactive.Append(1);
surfaceids.Append(0);
}
// checking
if (type == 2)
{
auto t0 = spline_in.GetSpline(0).GetTangent(0);
cout << "tstart (must be vertically): " << t0 << endl;
auto tn = spline_in.GetSpline(nsplines-1).GetTangent(1);
cout << "tend (must be vertically): " << tn << endl;
for (int i = 0; i < nsplines-1; i++)
{
auto ta = spline_in.GetSpline(i).GetTangent(1);
auto tb = spline_in.GetSpline(i+1).GetTangent(0);
cout << "sin (must not be 0) = " << abs(ta(0)*tb(1)-ta(1)*tb(0)) / (Abs(ta)*Abs(tb));
}
}
}
Revolution::~Revolution()
@ -764,8 +781,9 @@ namespace netgen
int intersections_before(0), intersections_after(0);
double randomx = 7.42357;
double randomy = 1.814756;
randomx *= 1./sqrt(randomx*randomx+randomy*randomy);
randomy *= 1./sqrt(randomx*randomx+randomy*randomy);
double randomlen = sqrt(randomx*randomx+randomy*randomy);
randomx *= 1./randomlen;
randomy *= 1./randomlen;
const double a = randomy;

5
libsrc/csg/revolution.hpp
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@ -67,7 +67,10 @@ namespace netgen
virtual double MaxCurvature () const;
//virtual double MaxCurvatureLoc (const Point<3> & /* c */ ,
// double /* rad */) const;
Point<3> P0() const { return p0; }
Vec<3> Axis() const { return v_axis; }
virtual void Project (Point<3> & p) const;
virtual Point<3> GetSurfacePoint () const;

102
libsrc/csg/specpoin.cpp
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@ -463,8 +463,35 @@ namespace netgen
return;
}
}
if (numprim == 2 &&
(typeid(*geometry->GetSurface(locsurf[0])) == typeid(RevolutionFace&)) &&
(typeid(*geometry->GetSurface(locsurf[1])) == typeid(RevolutionFace&)))
{
NgArray<Point<3>> pts;
bool check =
ComputeExtremalPoints (static_cast<const RevolutionFace*> (geometry->GetSurface(locsurf[0])),
static_cast<const RevolutionFace*> (geometry->GetSurface(locsurf[1])),
pts);
if (check)
{
// int cnt_inbox = 0;
for (auto p : pts)
if (box.IsIn(p))
{
AddPoint (p, layer);
// cnt_inbox++;
}
return;
/*
if (cnt_inbox == 0)
return;
*/
}
}
} // end if (numprim <= check_crosspoint)
possiblecrossp = (numprim >= 3) && calccp;
@ -608,9 +635,9 @@ namespace netgen
decision = 0;
}
}
// (*testout) << "l = " << level << " dec/sureexp = " << decision << sureexp << endl;
#ifdef DEVELOP
(*testout) << "edgepnt decision = " << decision << " sure = " << sureexp << endl;
#endif
if (decision && sureexp)
{
for (int k1 = 0; k1 < locsurf.Size() - 1; k1++)
@ -890,9 +917,18 @@ namespace netgen
f1->CalcGradient (p, g1);
f2->CalcGradient (p, g2);
if ( sqr (g1 * g2) > (1 - 1e-10) * Abs2 (g1) * Abs2 (g2))
return 1;
// if ( sqr (g1 * g2) > (1 - 1e-10) * Abs2 (g1) * Abs2 (g2))
// return 1;
if ( Abs2 (Cross(g1,g2)) < 1e-10 * Abs2 (g1) * Abs2 (g2)) // same, but stable
{
if (Abs2(vrs) < 1e-12*sqr(size)) // degenerate only if on both surfaces
return 1;
else
return 0;
}
for (int j = 0; j < 3; j++)
{
mat(0,j) = g1(j);
@ -1534,7 +1570,61 @@ namespace netgen
}
bool SpecialPointCalculation ::
ComputeExtremalPoints (const RevolutionFace * rev1,
const RevolutionFace * rev2,
NgArray<Point<3> > & pts)
{
// if (rev1 -> P0() != rev2 -> P0()) return false; // missing ????
if (Dist2 (rev1 -> P0(), rev2 -> P0()) > 1e-20*sqr(size)) return false;
// if (rev1 -> Axis() != rev2 -> Axis()) return false;
if ( (rev1 -> Axis()-rev2 -> Axis()).Length2() > 1e-16) return false;
Point<2> p1s = rev1->GetSpline().StartPI();
Point<2> p1e = rev1->GetSpline().EndPI();
Point<2> p2s = rev2->GetSpline().StartPI();
Point<2> p2e = rev2->GetSpline().EndPI();
Point<2> p2d;
if (Dist2(p1s,p2e) < 1e-20*sqr(size))
p2d = p1s;
else if (Dist2(p1e, p2s) < 1e-20*sqr(size))
p2d = p1e;
else
return false;
*testout << "Norm axis = " << rev1->Axis().Length() << endl;
Point<3> center = rev1->P0() + p2d(0)*rev1->Axis();
Vec<3> n = rev1->Axis();
// extremal points of circle, center, normal axis, radius p2d(1)
// Lagrange:
// L(x, lam1, lam2) = x_i + lam1 * (x-c)*v + lam2 * ( |x-c|^2 - r^2 )
for (double i = 0; i < 3; i++)
{
double lam1 = -n(i) / n.Length2();
Vec<3> ei(0,0,0); ei(i) = 1;
// double lam2 = 1/(2*p2d(1)) * sqrt(1 - sqr(n(i))/n.Length2());
double fac = 1-sqr(n(i))/n.Length2();
// if (fabs(lam2) > 1e-10)
if (fac > 1e-10)
{
double lam2 = 1/(2*p2d(1)) * sqrt(fac);
Point<3> x = center - 1.0/(2*lam2) * (ei + lam1*n);
pts.Append (x);
x = center + 1.0/(2*lam2) * (ei + lam1*n);
pts.Append (x);
/*
// check:
Point<2> p2d;
rev1 -> CalcProj (x, p2d);
*testout << "special solution, p2d = " << p2d << endl;
rev2 -> CalcProj (x, p2d);
*testout << "special solution, p2d = " << p2d << endl;
*/
}
}
return true;
}

3
libsrc/csg/specpoin.hpp
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@ -167,6 +167,9 @@ namespace netgen
const Sphere * sphere2,
NgArray<Point<3> > & pts);
bool ComputeExtremalPoints (const RevolutionFace * rev1,
const RevolutionFace * rev2,
NgArray<Point<3> > & pts);
void ComputeCrossPoints (const Plane * plane1,
const Plane * plane2,