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#pragma once
#include "point2d.hpp"
#include "../base/math.hpp"
#include "../std/limits.hpp"
#include "../std/static_assert.hpp"
// Similarly to namespace m2 - 2d math, this is a namespace for nd math.
namespace mn
{
template <typename PointT> class DistanceToLineSquare
{
private:
// we do not support unsigned points!!!
STATIC_ASSERT(numeric_limits<typename PointT::value_type>::is_signed);
public:
void SetEpsilon(double) {}
void SetBounds(PointT const & p0, PointT const & p1)
{
m_P0 = p0;
m_P1 = p1;
m_D = m_P1 - m_P0;
m_D2 = DotProduct(m_D, m_D);
m_D2 = sqrt(m_D2);
if (my::AlmostEqual(m_D2, 0.0))
{
// make zero vector - then all DotProduct will be equal to zero
m_D = m2::PointD(0, 0);
}
else
{
// normalize vector
m_D = m_D / m_D2;
}
}
double operator() (PointT Y) const
{
m2::PointD const YmP0 = Y - m_P0;
double const t = DotProduct(m_D, YmP0);
if (t <= 0)
{
// Y is closest to P0.
return DotProduct(YmP0, YmP0);
}
if (t >= m_D2)
{
// Y is closest to P1.
PointT const YmP1 = Y - m_P1;
return DotProduct(YmP1, YmP1);
}
// Closest point is interior to segment.
return my::sq(CrossProduct(YmP0, m_D));
}
private:
PointT m_P0, m_P1;
m2::PointD m_D;
double m_D2;
};
}
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