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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Routines for dealing with lines (intersections, etc.)
*
* Authors:
* Maximilian Albert <Anhalter42@gmx.de>
*
* Copyright (C) 2007 authors
*
* Released under GNU GPL v2+, read the file 'COPYING' for more information.
*/
#ifndef SEEN_LINE_GEOMETRY_H
#define SEEN_LINE_GEOMETRY_H
#include <2geom/point.h>
#include <optional>
#include "axis-manip.h" // FIXME: This is only for Box3D::epsilon; move that to a better location
#include "object/persp3d.h"
class SPDesktop;
typedef unsigned int guint32;
namespace Box3D {
class Line {
public:
Line(Geom::Point const &start, Geom::Point const &vec, bool is_endpoint = true);
Line(Line const &line);
virtual ~Line() = default;
Line &operator=(Line const &line);
virtual std::optional<Geom::Point> intersect(Line const &line);
inline Geom::Point direction () { return v_dir; }
Geom::Point closest_to(Geom::Point const &pt); // returns the point on the line closest to pt
friend inline std::ostream &operator<< (std::ostream &out_file, const Line &in_line);
std::optional<Geom::Point> intersection_with_viewbox (SPDesktop *desktop);
inline bool lie_on_same_side (Geom::Point const &A, Geom::Point const &B) {
/* If A is a point in the plane and n is the normal vector of the line then
the sign of dot(A, n) specifies the half-plane in which A lies.
Thus A and B lie on the same side if the dot products have equal sign. */
return ((Geom::dot(A, normal) - d0) * (Geom::dot(B, normal) - d0)) > 0;
}
double lambda (Geom::Point const pt);
inline Geom::Point point_from_lambda (double const lambda) {
return (pt + lambda * Geom::unit_vector (v_dir)); }
protected:
void set_direction(Geom::Point const &dir);
inline static bool pts_coincide (Geom::Point const pt1, Geom::Point const pt2)
{
return (Geom::L2 (pt2 - pt1) < epsilon);
}
Geom::Point pt;
Geom::Point v_dir;
Geom::Point normal;
Geom::Coord d0;
};
inline double determinant (Geom::Point const &a, Geom::Point const &b)
{
return (a[Geom::X] * b[Geom::Y] - a[Geom::Y] * b[Geom::X]);
}
std::pair<double, double> coordinates (Geom::Point const &v1, Geom::Point const &v2, Geom::Point const &w);
bool lies_in_sector (Geom::Point const &v1, Geom::Point const &v2, Geom::Point const &w);
bool lies_in_quadrangle (Geom::Point const &A, Geom::Point const &B, Geom::Point const &C, Geom::Point const &D, Geom::Point const &pt);
std::pair<Geom::Point, Geom::Point> side_of_intersection (Geom::Point const &A, Geom::Point const &B,
Geom::Point const &C, Geom::Point const &D,
Geom::Point const &pt, Geom::Point const &dir);
/** A function to print out the Line. It just prints out the coordinates of start point and
direction on the given output stream */
inline std::ostream &operator<< (std::ostream &out_file, const Line &in_line) {
out_file << "Start: " << in_line.pt << " Direction: " << in_line.v_dir;
return out_file;
}
} // namespace Box3D
#endif /* !SEEN_LINE_GEOMETRY_H */
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :
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