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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
parent b20ae1d3f5
commit f73afb8591
2 changed files with 65 additions and 5 deletions
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35
src/GCPnts/GCPnts_QuasiUniformDeflection.pxx
View File

@ -371,29 +371,54 @@ void QuasiFleche (const TheCurve& C,
Vdelta = Vfin;
}
// square length of chord
Standard_Real Norme = gp_Vec (Pdeb, Pdelta).SquareMagnitude();
Standard_Real theFleche = 0;
Standard_Boolean flecheok = Standard_False;
if (Norme > Eps)
if (Norme > Eps && Norme > 16. * Deflection2)
{
// Evaluation de la fleche par interpolation . Voir IntWalk_IWalking_5.gxx
Standard_Real N1 = Vdeb.SquareMagnitude();
Standard_Real N2 = Vdelta.SquareMagnitude();
if (N1 > Eps && N2 > Eps)
{
// square distance between ends of two normalized vectors [0; 4]
Standard_Real Normediff = (Vdeb.Normalized().XYZ() - Vdelta.Normalized().XYZ()).SquareModulus();
if (Normediff > Eps)
{
theFleche = Normediff * Norme / 64.;
// So, fleche <= (Norme / 16), independently of Vdeb and Vdelta.
// And if (Norme / 16) < Deflection2, this approach gives
// fleche < Deflection2 independently of real curve.
// That is why we exclude case Norme < (16. * Deflection2)
flecheok = Standard_True;
}
}
}
if (!flecheok)
gp_Pnt Pmid ((Pdeb.XYZ() + Pdelta.XYZ()) * 0.5);
gp_Pnt Pverif (Value (C, Udeb + Udelta * 0.5));
Standard_Real FlecheMidMid = Pmid.SquareDistance (Pverif);
if (flecheok)
{
gp_Pnt Pmid ((Pdeb.XYZ() + Pdelta.XYZ()) * 0.5);
gp_Pnt Pverif (Value(C, Udeb + Udelta * 0.5));
theFleche = Pmid.SquareDistance (Pverif);
// Algorithm, evaluating "fleche" by interpolation,
// can give false-positive result.
// So we check also distance between Pmid and Pverif (FlecheMidMid).
// But FlecheMidMid gives worse result in case of non-uniform parameterisation.
// Maximum FlecheMidMid, that seems reasonable, is (chord/2)^2 + Deflection2
// .---------------.Pverif .
// | | | Deflection
// ._______. ______. .
// Pdeb Pmid Pdelta
if (FlecheMidMid > Norme/4. + Deflection2)
{
theFleche = FlecheMidMid;
}
}
else
{
theFleche = FlecheMidMid;
}
if (theFleche < Deflection2)

35
tests/bugs/moddata_3/bug33828 Normal file
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@ -0,0 +1,35 @@
puts "==========================================================="
puts "0033828: Modeling Data - GCPnts_QuasiUniformDeflection"
puts "returns very different results under small change in deflection"
puts "==========================================================="
proc check_crvpoints {cc deflection nb_expected} {
upvar ${cc} ${cc}
set str1 "Nb points +: +(\[-0-9.+eE\]+)\n"
set str2 "Max defl: +(\[-0-9.+eE\]+) +(\[-0-9.+eE\]+) +(\[-0-9.+eE\]+) +(\[-0-9.+eE\]+)"
set info [crvpoints r ${cc} ${deflection}]
regexp "${str1}${str2}" ${info} full Nb dmax ufmax ulmax i
if { ${Nb} != ${nb_expected} } {
puts "Error : bad value of Nb points = ${Nb}, expected ${nb_expected}"
}
if { ${dmax} > ${deflection} } {
puts "Error : bad value of maximum deflection = ${dmax}, expected < ${deflection}"
}
}
bsplinecurve cu 3 7 0 4 0.17 2 0.33 2 0.5 2 0.67 2 0.83 2 1 4 0.163 0.233 0 1 0.158 0.204 0 1 0.139 0.180 0 1 0.086 0.159 0 1 0.055 0.163 0 1 0.009 0.196 0 1 -0.004 0.225 0 1 0.002 0.281 0 1 0.019 0.307 0 1 0.070 0.332 0 1 0.101 0.331 0 1 0.149 0.301 0 1 0.164 0.274 0 1 0.163 0.246 0 1
check_crvpoints cu .5 2
check_crvpoints cu .1 3
check_crvpoints cu .05 5
check_crvpoints cu .025 5
check_crvpoints cu .007 9
check_crvpoints cu .005 17
check_crvpoints cu .0005 33
check_crvpoints cu .0003 65
check_crvpoints cu .0002 65
check_crvpoints cu .0001 73