Straight Rays ( ray )

Definition

An instance r of the data type ray is a directed straight ray in the two-dimensional plane. The angle between a right oriented horizontal ray and r is called the direction of r.

#include < LEDA/geo/ray.h >

Types

ray::coord_type	the coordinate type (double).
ray::point_type	the point type (point).

Creation

ray	r(const point& p, const point& q)
		introduces a variable r of type ray. r is initialized to the ray starting at point p and passing through point q.
ray	r(const segment& s)	introduces a variable r of type ray. r is initialized to ray(s.source(), s.target()).
ray	r(const point& p, const vector& v)
		introduces a variable r of type ray. r is initialized to ray(p, p + v).
ray	r(const point& p, double alpha)
		introduces a variable r of type ray. r is initialized to the ray starting at point p with direction alpha.
ray	r	introduces a variable r of type ray. r is initialized to the ray starting at the origin with direction 0.
ray	r(const ray& r1, int)	introduces a variable r of type ray. r is initialized to a copy of r1. The second argument is for compatibility with rat_ray.

Operations

point	r.source()	returns the source of r.
point	r.point1()	returns the source of r.
point	r.point2()	returns a point on r different from r.source().
double	r.direction()	returns the direction of r.
double	r.angle(const ray& s)	returns the angle between r and s, i.e., s.direction() - r.direction().
bool	r.is_vertical()	returns true iff r is vertical.
bool	r.is_horizontal()	returns true iff r is horizontal.
double	r.slope()	returns the slope of the straight line underlying r. Precondition r is not vertical.
bool	r.intersection(const ray& s, point& inter)
		if r and s intersect in a single point this point is assigned to inter and the result is true, otherwise the result is false.
bool	r.intersection(const segment& s, point& inter)
		if r and s intersect in a single point this point is assigned to inter and the result is true, otherwise the result is false.
bool	r.intersection(const segment& s)
		test if r and s intersect.
ray	r.translate_by_angle(double a, double d)
		returns r translated in direction a by distance d.
ray	r.translate(double dx, double dy)
		returns r translated by vector (dx, dy).
ray	r.translate(const vector& v)
		returns r translated by vector v Precondition v.dim() = 2.
ray	r + const vector& v	returns r translated by vector v.
ray	r - const vector& v	returns r translated by vector - v.
ray	r.rotate(const point& q, double a)
		returns r rotated about point q by angle a.
ray	r.rotate(double a)	returns r.rotate( point(0, 0), a).
ray	r.rotate90(const point& q, int i=1)
		returns r rotated about q by an angle of i x 90 degrees. If i > 0 the rotation is counter-clockwise otherwise it is clockwise.
ray	r.reflect(const point& p, const point& q)
		returns r reflected across the straight line passing through p and q.
ray	r.reflect(const point& p)	returns r reflected across point p.
ray	r.reverse()	returns r reversed.
bool	r.contains(const point& )	decides whether r contains p.
bool	r.contains(const segment& )
		decides whether r contains s.

Non-Member Functions

int	orientation(const ray& r, const point& p)
		computes orientation(a, b, p), where a $\not=$b and a and b appear in this order on ray r.
int	cmp_slopes(const ray& r1, const ray& r2)
		returns compare(slope(r1), slope(r2)) where slope(ri) denotes the slope of the straight line underlying ri.