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0033828: Modeling Algorithms - GCPnts_QuasiUniformDeflection returns very different results under small change in deflection

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jfa
2024-09-17 17:51:36 +01:00
committed by dpasukhi
parent d8a26498d2
commit b0922ff9a1
2 changed files with 66 additions and 5 deletions
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36
src/GCPnts/GCPnts_QuasiUniformDeflection.cxx
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@@ -103,29 +103,55 @@ static void QuasiFleche (const TheCurve& theC,
aVdelta = theVfin;
}
// square length of chord
const Standard_Real aNorme = gp_Vec (thePdeb, aPdelta).SquareMagnitude();
Standard_Real aFleche = 0.0;
Standard_Boolean isFlecheOk = Standard_False;
if (aNorme > theEps)
if (aNorme > theEps && aNorme > 16. * theDeflection2)
{
// Evaluation de la fleche par interpolation . Voir IntWalk_IWalking_5.gxx
Standard_Real N1 = theVdeb.SquareMagnitude();
Standard_Real N2 = aVdelta.SquareMagnitude();
if (N1 > theEps && N2 > theEps)
{
// square distance between ends of two normalized vectors [0; 4]
Standard_Real aNormediff = (theVdeb.Normalized().XYZ() - aVdelta.Normalized().XYZ()).SquareModulus();
if (aNormediff > theEps)
{
aFleche = aNormediff * aNorme / 64.0;
// So, fleche <= (aNorme / 16), independently of Vdeb and Vdelta.
// And if (aNorme / 16) < theDeflection2, this approach gives
// fleche < theDeflection2 independently of real curve.
// That is why we exclude case aNorme < (16. * theDeflection2)
isFlecheOk = Standard_True;
}
}
}
if (!isFlecheOk)
gp_Pnt aPmid ((thePdeb.XYZ() + aPdelta.XYZ()) * 0.5);
gp_Pnt aPverif (Value (theC, theUdeb + aUdelta * 0.5));
Standard_Real aFlecheMidMid = aPmid.SquareDistance (aPverif);
if (isFlecheOk)
{
gp_Pnt aPmid ((thePdeb.XYZ() + aPdelta.XYZ()) * 0.5);
gp_Pnt aPverif (Value (theC, theUdeb + aUdelta * 0.5));
aFleche = aPmid.SquareDistance (aPverif);
// Algorithm, evaluating "fleche" by interpolation,
// can give false-positive result.
// So we check also distance between Pmid and Pverif (aFlecheMidMid).
// But aFlecheMidMid gives worse result in case of non-uniform parameterisation.
// Maximum aFlecheMidMid, that seems reasonable, is (chord/2)^2 + theDeflection2
// .---------------.Pverif .
// | | | Deflection
// ._______. ______. .
// Pdeb Pmid Pdelta
if (aFlecheMidMid > aNorme/4. + theDeflection2)
//if (aFlecheMidMid > aNorme/4.)
{
aFleche = aFlecheMidMid;
}
}
else
{
aFleche = aFlecheMidMid;
}
if (aFleche < theDeflection2)