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0030082: Intersection algorithm returns curve with big tolerance value

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The fix inserts new points at the end of the WLine in case when the direction of the intersection curve is significantly changed.
This commit is contained in:
nbv
2018-08-23 16:37:59 +03:00
committed by bugmaster
parent 4a056d205b
commit 7eb3580b79
3 changed files with 180 additions and 2 deletions
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88
src/IntPatch/IntPatch_ImpImpIntersection_4.gxx
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@@ -3376,6 +3376,90 @@ static IntPatch_ImpImpIntersection::IntStatus
if (aPf.IsSame(aPl, Precision::Confusion()))
isGood = Standard_False;
}
else if (aWLine[i]->NbPnts() > 2)
{
// Sometimes points of the WLine are distributed
// linearly and uniformly. However, such position
// of the points does not always describe the real intersection
// curve. I.e. real tangents at the ends of the intersection
// curve can significantly deviate from this "line" direction.
// Here we are processing this case by inserting additional points
// to the beginning/end of the WLine to make it more precise.
// See description to the issue #30082.
const Standard_Real aSqTol3D = aTol3D*aTol3D;
for (Standard_Integer j = 0; j < 2; j++)
{
// If j == 0 ==> add point at begin of WLine.
// If j == 1 ==> add point at end of WLine.
for (;;)
{
if (aWLine[i]->NbPnts() >= aNbMaxPoints)
{
break;
}
// Take 1st and 2nd point to compute the "line" direction.
// For our convenience, we make 2nd point be the ends of the WLine
// because it will be used for computation of the normals
// to the surfaces.
const Standard_Integer anIdx1 = j ? aWLine[i]->NbPnts() - 1 : 2;
const Standard_Integer anIdx2 = j ? aWLine[i]->NbPnts() : 1;
const gp_Pnt &aP1 = aWLine[i]->Point(anIdx1).Value();
const gp_Pnt &aP2 = aWLine[i]->Point(anIdx2).Value();
const gp_Vec aDir(aP1, aP2);
if (aDir.SquareMagnitude() < aSqTol3D)
{
break;
}
// Compute tangent in first/last point of the WLine.
// We do not take into account the flag "isReversed"
// because strict direction of the tangent is not
// important here (we are interested in the tangent
// line itself and nothing to fear if its direction
// is reversed).
const gp_Vec aN1 = aQuad1.Normale(aP2);
const gp_Vec aN2 = aQuad2.Normale(aP2);
const gp_Vec aTg(aN1.Crossed(aN2));
if (aTg.SquareMagnitude() < Precision::SquareConfusion())
{
// Tangent zone
break;
}
// Check of the bending
Standard_Real anAngle = aDir.Angle(aTg);
if (anAngle > M_PI_2)
anAngle -= M_PI;
if (Abs(anAngle) > 0.25) // ~ 14deg.
{
const Standard_Integer aNbPntsPrev = aWLine[i]->NbPnts();
SeekAdditionalPoints(aQuad1, aQuad2, aWLine[i]->Curve(),
anEquationCoeffs, i, 3, anIdx1, anIdx2,
aTol2D, aPeriod, isReversed);
if (aWLine[i]->NbPnts() == aNbPntsPrev)
{
// No points have been added. ==> Exit from a loop.
break;
}
}
else
{
// Good result has been achieved. ==> Exit from a loop.
break;
}
} // for (;;)
}
}
if (isGood)
{
@@ -3383,8 +3467,8 @@ static IntPatch_ImpImpIntersection::IntStatus
isAddedIntoWL[i] = Standard_True;
SeekAdditionalPoints(aQuad1, aQuad2, aWLine[i]->Curve(),
anEquationCoeffs, i, aNbPoints, 1,
aWLine[i]->NbPnts(), aTol2D, aPeriod,
isReversed);
aWLine[i]->NbPnts(), aTol2D, aPeriod,
isReversed);
aWLine[i]->ComputeVertexParameters(aTol3D);
theSlin.Append(aWLine[i]);