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0025782: The result of intersection between two cylinders is incorrect

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1. Cylinders are tangent to each other indeed. Fix processes this case.
2. Algorithm of intersection line computing (in case of cylinders with two parallel axes) has been changed.

Test cases for issue CR25782
This commit is contained in:
nbv
2015-02-11 09:16:00 +03:00
committed by bugmaster
parent b8f2022f8c
commit b70d2b0999
3 changed files with 247 additions and 20 deletions
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95
src/IntAna/IntAna_QuadQuadGeo.cxx
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@@ -977,6 +977,8 @@ void IntAna_QuadQuadGeo::Perform(const gp_Cylinder& Cyl1,
gp_Dir DirCyl = Cyl1.Position().Direction();
Standard_Real ProjP2OnDirCyl1=gp_Vec(DirCyl).Dot(gp_Vec(P1,P2t));
//P2 is a projection the location of the 2nd cylinder on the base
//of the 1st cylinder
P2.SetCoord(P2t.X() - ProjP2OnDirCyl1*DirCyl.X(),
P2t.Y() - ProjP2OnDirCyl1*DirCyl.Y(),
P2t.Z() - ProjP2OnDirCyl1*DirCyl.Z());
@@ -987,7 +989,7 @@ void IntAna_QuadQuadGeo::Perform(const gp_Cylinder& Cyl1,
typeres=IntAna_Empty;
nbint=0;
}
else if(DistA1A2>(R1pR2))
else if((R1pR2 - DistA1A2) <= RealSmall())
{
//-- 1 Tangent line -------------------------------------OK
typeres=IntAna_Line;
@@ -1005,32 +1007,85 @@ void IntAna_QuadQuadGeo::Perform(const gp_Cylinder& Cyl1,
typeres=IntAna_Line;
nbint=2;
dir1=DirCyl;
gp_Vec P1P2(P1,P2);
gp_Dir DirA1A2=gp_Dir(P1P2);
gp_Dir Ortho_dir1_P1P2 = dir1.Crossed(DirA1A2);
dir2=dir1;
Standard_Real Alpha=0.5*(R1*R1-R2*R2+DistA1A2*DistA1A2)/(DistA1A2);
//Standard_Real Beta = Sqrt(R1*R1-Alpha*Alpha);
Standard_Real anSqrtArg = R1*R1-Alpha*Alpha;
Standard_Real Beta = (anSqrtArg > 0.) ? Sqrt(anSqrtArg) : 0.;
const Standard_Real aR1R1 = R1*R1;
/*
P1
o
* | *
* O1| *
A o-----o-----o B
* | *
* | *
o
P2
Two cylinders have axes collinear. Therefore, problem can be reformulated as
to find intersection point of two circles (the bases of the cylinders) on
the plane: 1st circle has center P1 and radius R1 (the radius of the
1st cylinder) and 2nd circle has center P2 and radius R2 (the radius of the
2nd cylinder). The plane is the base of the 1st cylinder. Points A and B
are intersection point of these circles. Distance P1P2 is equal to DistA1A2.
O1 is the intersection point of P1P2 and AB segments.
At that, if distance AB < Tol we consider that the circles are tangent and
has only one intersection point.
AB = 2*R1*sin(angle AP1P2).
Accordingly,
AB^2 < Tol^2 => 4*R1*R1*sin(angle AP1P2)^2 < Tol*Tol.
*/
if((Beta+Beta)<Tol)
//Cosine and Square of Sine of the A-P1-P2 angle
const Standard_Real aCos = 0.5*(aR1R1-R2*R2+DistA1A2*DistA1A2)/(R1*DistA1A2);
const Standard_Real aSin2 = 1-aCos*aCos;
const Standard_Boolean isTangent =((4.0*aR1R1*aSin2) < Tol*Tol);
//Normalized vector P1P2
const gp_Vec DirA1A2((P2.XYZ() - P1.XYZ())/DistA1A2);
if(isTangent)
{
//Intercept the segment from P1 point along P1P2 direction
//and having |P1O1| length
nbint=1;
pt1.SetCoord( P1.X() + Alpha*DirA1A2.X()
,P1.Y() + Alpha*DirA1A2.Y()
,P1.Z() + Alpha*DirA1A2.Z());
pt1.SetXYZ(P1.XYZ() + DirA1A2.XYZ()*R1*aCos);
}
else
{
pt1.SetCoord( P1.X() + Alpha*DirA1A2.X() + Beta*Ortho_dir1_P1P2.X(),
P1.Y() + Alpha*DirA1A2.Y() + Beta*Ortho_dir1_P1P2.Y(),
P1.Z() + Alpha*DirA1A2.Z() + Beta*Ortho_dir1_P1P2.Z());
pt2.SetCoord( P1.X() + Alpha*DirA1A2.X() - Beta*Ortho_dir1_P1P2.X(),
P1.Y() + Alpha*DirA1A2.Y() - Beta*Ortho_dir1_P1P2.Y(),
P1.Z() + Alpha*DirA1A2.Z() - Beta*Ortho_dir1_P1P2.Z());
{
//Sine of the A-P1-P2 angle (if aSin2 < 0 then isTangent == TRUE =>
//go to another branch)
const Standard_Real aSin = sqrt(aSin2);
//1. Rotate P1P2 to the angle A-P1-P2 relative to P1
//(clockwise and anticlockwise for getting
//two intersection points).
//2. Intercept the segment from P1 along direction,
//determined in the preview paragraph and having R1 length
const gp_Dir &aXDir = Cyl1.Position().XDirection(),
&aYDir = Cyl1.Position().YDirection();
const gp_Vec aR1Xdir = R1*aXDir.XYZ(),
aR1Ydir = R1*aYDir.XYZ();
//Source 2D-coordinates of the P1P2 vector normalized
//in coordinate system, based on the X- and Y-directions
//of the 1st cylinder in the plane of the 1st cylinder base
//(P1 is the origin of the coordinate system).
const Standard_Real aDx = DirA1A2.Dot(aXDir),
aDy = DirA1A2.Dot(aYDir);
//New coordinate (after rotation) of the P1P2 vector normalized.
Standard_Real aNewDx = aDx*aCos - aDy*aSin,
aNewDy = aDy*aCos + aDx*aSin;
pt1.SetXYZ(P1.XYZ() + aNewDx*aR1Xdir.XYZ() + aNewDy*aR1Ydir.XYZ());
aNewDx = aDx*aCos + aDy*aSin;
aNewDy = aDy*aCos - aDx*aSin;
pt2.SetXYZ(P1.XYZ() + aNewDx*aR1Xdir.XYZ() + aNewDy*aR1Ydir.XYZ());
}
}
else if(DistA1A2>(RmR-Tol))