Intersection2DImpl.hpp

/* $ Id: $ */

namespace jafar {
  namespace geom {
    template<>
    inline bool intersection( const Line<2>& l1, const Line<2>& l2, Atom<2>::HomogenousVecD& _vec )
    {
      typedef Atom<2>::HomogenousVecD HomogenousVec;
      HomogenousVec v1 = l1.pointAt(0.0); double x1 = v1(0); double y1 = v1(1);
      HomogenousVec v2 = l1.pointAt(1.0); double x2 = v2(0); double y2 = v2(1);
      HomogenousVec v3 = l2.pointAt(0.0); double x3 = v3(0); double y3 = v3(1);
      HomogenousVec v4 = l2.pointAt(1.0); double x4 = v4(0); double y4 = v4(1);
      double d = (x1 - x2)*(y3 - y4) - (y1 - y2)*(x3 - x4);
      if(fabs(d) < 1e-6) return false;
      _vec(2) = 1.0;
      double x1y2my1x2 = ( x1 * y2 - y1 * x2 );
      double x3y4my3x4 = ( x3 * y4 - y3 * x4 );
      _vec(0) = ( x1y2my1x2 * ( x3 - x4 ) - ( x1 - x2 ) * x3y4my3x4 ) / d;
      _vec(1) = ( x1y2my1x2 * ( y3 - y4 ) - ( y1 - y2 ) * x3y4my3x4 ) / d;
      return false;
    } 

  }
}