CGAL::Triangle_2<Kernel>

Definition

²

The boundary of a triangle splits the plane in two open regions, a bounded one and an unbounded one.

Creation

Triangle_2<Kernel> t ( Point_2<Kernel> p, Point_2<Kernel> q, Point_2<Kernel> r);
	introduces a triangle t with vertices $$p, $$q and $$r.

Operations

bool	t.operator== ( t2)
		Test for equality: two triangles are equal, iff there exists a cyclic permutation of the vertices of $$t2, such that they are equal to the vertices of t.
bool	t.operator!= ( t2)
		Test for inequality.
Point_2<Kernel>	t.vertex ( int i)	returns the i'th vertex modulo 3 of t.
Point_2<Kernel>	t.operator[] ( int i)
		returns vertex(i).

Predicates

bool	t.is_degenerate ()	triangle t is degenerate, if the vertices are collinear.
Orientation	t.orientation ()	returns the orientation of t.
Oriented_side	t.oriented_side ( Point_2<Kernel> p)
		returns ON_ORIENTED_BOUNDARY, or POSITIVE_SIDE, or the constant ON_NEGATIVE_SIDE, determined by the position of point $$p. Precondition: t is not degenerate.
Bounded_side	t.bounded_side ( Point_2<Kernel> p)
		returns the constant ON_BOUNDARY, ON_BOUNDED_SIDE, or else ON_UNBOUNDED_SIDE, depending on where point $$p is. Precondition: t is not degenerate.

For convenience we provide the following boolean functions:

bool	t.has_on_positive_side ( Point_2<Kernel> p)
bool	t.has_on_negative_side ( Point_2<Kernel> p)
bool	t.has_on_boundary ( Point_2<Kernel> p)
bool	t.has_on_bounded_side ( Point_2<Kernel> p)
bool	t.has_on_unbounded_side ( Point_2<Kernel> p)
		Precondition: t is not degenerate.

Miscellaneous

Triangle_2<Kernel>	t.opposite ()	returns a triangle where the boundary is oriented the other way round (this flips the positive and the negative side, but not the bounded and unbounded side).
Kernel::FT	t.area ()	returns the signed area of t.
Bbox_2	t.bbox ()	returns a bounding box containing t.
Triangle_2<Kernel>	t.transform ( Aff_transformation_2<Kernel> at)
		returns the triangle obtained by applying $$at on the three vertices of t.

See Also

Kernel::Triangle_2