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#include "geometry/line2d.hpp"
#include <cmath>
#include <sstream>
using namespace std;
namespace m2
{
namespace
{
bool Collinear(PointD const & a, PointD const & b, double eps)
{
return fabs(CrossProduct(a, b)) < eps;
}
} // namespace
string DebugPrint(Line2D const & line)
{
ostringstream os;
os << "Line2D [ ";
os << "point: " << DebugPrint(line.m_point) << ", ";
os << "direction: " << DebugPrint(line.m_direction);
os << " ]";
return os.str();
}
IntersectionResult Intersect(Line2D const & lhs, Line2D const & rhs, double eps)
{
auto const & a = lhs.m_point;
auto const & ab = lhs.m_direction;
auto const & c = rhs.m_point;
auto const & cd = rhs.m_direction;
if (Collinear(ab, cd, eps))
{
if (Collinear(c - a, cd, eps))
return IntersectionResult(IntersectionResult::Type::Infinity);
return IntersectionResult(IntersectionResult::Type::Zero);
}
auto const ac = c - a;
auto const n = CrossProduct(ac, cd);
auto const d = CrossProduct(ab, cd);
auto const scale = n / d;
return IntersectionResult(a + ab * scale);
}
} // namespace m2
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