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bugfix in csg2d

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handle degenerate quadratic equation in intersection of spline and
segment correctly
This commit is contained in:
Matthias Hochsteger 2020-11-13 16:09:59 +01:00
parent 6b5ba0b072
commit 22d6303c5c
1 changed files with 22 additions and 8 deletions
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18
libsrc/geom2d/csg2d.cpp
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@ -250,13 +250,20 @@ IntersectionType IntersectSplineSegment( const Spline & s, const Point<2> & r0,
double det = b_*b_ - 4*a_*c_; double det = b_*b_ - 4*a_*c_;
if(det<0.0) if(det<0.0)
return NO_INTERSECTION; return NO_INTERSECTION;
double t;
if(fabs(a_)>EPSILON)
{
double sqrt_det = sqrt(det); double sqrt_det = sqrt(det);
double t1 = 1.0/(2*a_) * (-b_ + sqrt_det); double t1 = 1.0/(2*a_) * (-b_ + sqrt_det);
double t2 = 1.0/(2*a_) * (-b_ - sqrt_det); double t2 = 1.0/(2*a_) * (-b_ - sqrt_det);
t = min(t1, t2);
double t = min(t1,t2);
if(t<alpha) if(t<alpha)
t = max(t1,t2); t = max(t1,t2);
}
else // degenerate quadratic equation
t = -c_/b_;
if(t+EPSILON<alpha) if(t+EPSILON<alpha)
return NO_INTERSECTION; return NO_INTERSECTION;
@ -288,10 +295,17 @@ IntersectionType IntersectSplineSegment1( const Spline & s, const Point<2> & r0,
double det = b_*b_ - 4*a_*c_; double det = b_*b_ - 4*a_*c_;
if(det<0.0) if(det<0.0)
return NO_INTERSECTION; return NO_INTERSECTION;
double sqrt_det = sqrt(det); double sqrt_det = sqrt(det);
double vbeta[2]; double vbeta[2];
if(fabs(a_)>EPSILON)
{
vbeta[0] = 1.0/(2*a_) * (-b_ + sqrt_det); vbeta[0] = 1.0/(2*a_) * (-b_ + sqrt_det);
vbeta[1] = 1.0/(2*a_) * (-b_ - sqrt_det); vbeta[1] = 1.0/(2*a_) * (-b_ - sqrt_det);
}
else // degenrate quadratic equation
vbeta[0] = vbeta[1] = -c_/b_;
int dim = fabs(vr[0]) > fabs(vr[1]) ? 0 : 1; int dim = fabs(vr[0]) > fabs(vr[1]) ? 0 : 1;
double valpha[2]; double valpha[2];