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#pragma once
#include "rect2d.hpp"
#include "point2d.hpp"
namespace m2
{
namespace detail
{
// bit masks for code kinds
static const int LEFT = 1;
static const int RIGHT = 2;
static const int BOT = 4;
static const int TOP = 8;
// return accumulated bit mask for point-rect interaction
template <class T>
int vcode(m2::Rect<T> const & r, m2::Point<T> const & p)
{
return ((p.x < r.minX() ? LEFT : 0) +
(p.x > r.maxX() ? RIGHT : 0) +
(p.y < r.minY() ? BOT : 0) +
(p.y > r.maxY() ? TOP : 0));
}
}
template <class T>
bool Intersect(m2::Rect<T> const & r, m2::Point<T> & p1, m2::Point<T> & p2)
{
int code[2] = { detail::vcode(r, p1), detail::vcode(r, p2) };
// do while one of the point is out of rect
while (code[0] || code[1])
{
if (code[0] & code[1])
{
// both point area on the one side of rect
return false;
}
// choose point with non-zero code
m2::Point<T> * pp;
int i;
if (code[0])
{
i = 0;
pp = &p1;
}
else
{
i = 1;
pp = &p2;
}
// added points compare to avoid NAN numbers
if (code[i] & detail::LEFT)
{
if (p1 == p2) return false;
pp->y += (p1.y - p2.y) * (r.minX() - pp->x) / (p1.x - p2.x);
pp->x = r.minX();
}
else if (code[i] & detail::RIGHT)
{
if (p1 == p2) return false;
pp->y += (p1.y - p2.y) * (r.maxX() - pp->x) / (p1.x - p2.x);
pp->x = r.maxX();
}
if (code[i] & detail::BOT)
{
if (p1 == p2) return false;
pp->x += (p1.x - p2.x) * (r.minY() - pp->y) / (p1.y - p2.y);
pp->y = r.minY();
}
else if (code[i] & detail::TOP)
{
if (p1 == p2) return false;
pp->x += (p1.x - p2.x) * (r.maxY() - pp->y) / (p1.y - p2.y);
pp->y = r.maxY();
}
// update code with new point
code[i] = detail::vcode(r, *pp);
}
// both codes are equal to zero => points area inside rect
return true;
}
}
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