Version 5.0 The LEDA User Manual

eal point p.reflect(const real point& q, const real point& r)
real point p.reflect(const real point& q)
real vector p − const real point& q
returns p reflected across the straight line passing
through q and r.
returns p reflected across point q.
returns the difference vector of the coordinates.
Non-Member Functions
int cmp distances(const real point& p1 , const real point& p2 ,
const real point& p3 , const real point& p4 )
compares the distances (p1 , p2 ) and (p3 , p4 ). Returns
+1 (−1) if distance (p1 , p2 ) is larger (smaller) than distance
(p3 , p4 ), otherwise 0.
real point center(const real point& a, const real point& b)
returns the center of a and b, i.e. a + ⃗ ab/2.
real point midpoint(const real point& a, const real point& b)
returns the center of a and b.
int orientation(const real point& a, const real point& b, const real point& c)
computes the orientation of points a, b, and c as the
sign of the determinant
∣
a x a y 1
b x b y 1
c x c y 1
∣
i.e., it returns +1 if point c lies left of the directed line
through a and b, 0 if a,b, and c are collinear, and −1
otherwise.
int cmp signed dist(const real point& a, const real point& b, const real point& c,
const real point& d)
compares (signed) distances of c and d to the straight
line passing through a and b (directed from a to b). Returns
+1 (−1) if c has larger (smaller) distance than d
and 0 if distances are equal.