line.h

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#pragma once
 
#include "./point.h"
#include "./vector.h"
 
#include <array>
 
namespace emlabcpp
{
 
// represents an set of two points, type alies of std::array because nothing more specific is
// required
template < std::size_t N >
using line = std::array< point< N >, 2 >;
 
// calculate shortest distance between any point on line and point 'p'
template < std::size_t N >
constexpr float distance_of( line< N > const& l, point< N > const& p )
{
        vector< N > const direction      = l[1] - l[0];
        float const       length_squared = length2_of( direction );
        if ( length_squared == 0.f )
                return distance_of( p, l[0] );
        float projection_dist = dot( p - l[0], direction );
        projection_dist /= length_squared;
        projection_dist = std::clamp( projection_dist, 0.f, 1.f );
 
        point< N > const closest_p = l[0] + projection_dist * direction;
 
        return distance_of( closest_p, p );
}
 
template < std::size_t N >
constexpr float distance_of( point< N > const& p, line< N > const& line )
{
        return distance_of( line, p );
}
 
}  // namespace emlabcpp