Vector2.cc

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#include <blort/Recognizer3D/Vector2.hh>

namespace P 
{

Vector2 LineIntersection(const Vector2 &p1, const Vector2 &d1,
    const Vector2 &p2, const Vector2 &d2) throw(Except)
{
  double d = Cross(d2, d1);
  if(d == 0.)
    throw Except(__HERE__, "lines do not intersect");
  double l = Cross(d2, p2 - p1)/d;
  return Vector2(p1.x + l*d1.x, p1.y + l*d1.y);
}

Vector2 LineIntersection(const Vector2 &p1, const Vector2 &d1,
    const Vector2 &p2, const Vector2 &d2, double *l1, double *l2) throw(Except)
{
  double d = Cross(d2, d1);
  if(d == 0.)
    throw Except(__HERE__, "lines do not intersect");
  Vector2 p12 = p2 - p1;
  *l1 = Cross(d2, p12)/d;
  *l2 = Cross(d1, p12)/d;
  return Vector2(p1.x + *l1*d1.x, p1.y + *l1*d1.y);
}

bool LinesIntersecting(const Vector2 &a1, const Vector2 &a2,
    const Vector2 &b1, const Vector2 &b2)
{
  double l1 = 0., l2 = 0.;
  LineIntersection(a1, a2 - a1, b1, b2 - b1, &l1, &l2);
  return (l1 >= 0. && l1 <= 1.) && (l2 >= 0. && l2 <= 1.);
}

bool LinesIntersecting(const Vector2 &a1, const Vector2 &a2,
    const Vector2 &b1, const Vector2 &b2, Vector2 &isct)
{
  double l1 = 0., l2 = 0.;
  isct=LineIntersection(a1, a2 - a1, b1, b2 - b1, &l1, &l2);
  return (l1 >= 0. && l1 <= 1.) && (l2 >= 0. && l2 <= 1.);
}

}