Find Point of Intersection of Two Lines

 

pdd LinesIntersection(pdd A, pdd B, pdd C, pdd D)

{

    // Line AB represented as a1x + b1y = c1

    double a1 = B.second - A.second;

    double b1 = A.first - B.first;

    double c1 = a1*(A.first) + b1*(A.second);

  

    // Line CD represented as a2x + b2y = c2

    double a2 = D.second - C.second;

    double b2 = C.first - D.first;

    double c2 = a2*(C.first)+ b2*(C.second);

  

    double determinant = a1*b2 - a2*b1;

  

    if (determinant == 0)

    {

        // The lines are parallel. This is simplified

        // by returning a pair of FLT_MAX

        return make_pair(FLT_MAX, FLT_MAX);

    }

    else

    {

        double x = (b2*c1 - b1*c2)/determinant;

        double y = (a1*c2 - a2*c1)/determinant;

        return make_pair(x, y);

    }

}