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An object of the class Vector_2<Kernel> is a vector in the two-dimensional vector space ℝ2. Geometrically spoken, a vector is the difference of two points p2, p1 and denotes the direction and the distance from p1 to p2.
Cgal defines a symbolic constant NULL_VECTOR. We will explicitly state where you can pass this constant as an argument instead of a vector initialized with zeros.
| Vector_2<Kernel>::Cartesian_const_iterator | |
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An iterator for enumerating the
Cartesian
coordinates of a vector.
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| Vector_2<Kernel> v ( Point_2<Kernel> a, Point_2<Kernel> b); | |||
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introduces the vector b-a.
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| Vector_2<Kernel> v ( Segment_2<Kernel> s); | |||
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introduces the vector s.target()-s.source().
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| Vector_2<Kernel> v ( Ray_2<Kernel> r); | |||
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introduces the vector having the same direction as r.
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| Vector_2<Kernel> v ( Line_2<Kernel> l); | |||
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introduces the vector having the same direction as l.
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| Vector_2<Kernel> v ( Null_vector NULL_VECTOR); | |||
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introduces a null vector v.
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| Vector_2<Kernel> v ( int x, int y); | |||
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introduces a vector v initialized to (x,y).
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| Vector_2<Kernel> v ( double x, double y); | |||
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introduces a vector v initialized to (x,y).
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| Vector_2<Kernel> v ( Kernel::RT hx, Kernel::RT hy, Kernel::RT hw = RT(1)); | |||
introduces a vector v initialized to (hx/hw,hy/hw).
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| Vector_2<Kernel> v ( Kernel::FT x, Kernel::FT y); | |||
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introduces a vector v initialized to (x,y).
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| bool | v.operator== ( w) const | Test for equality: two vectors are equal, iff their x and y coordinates are equal. You can compare a vector with the NULL_VECTOR. |
| bool | v.operator!= ( w) const | Test for inequality. You can compare a vector with the NULL_VECTOR. |
There are two sets of coordinate access functions, namely to the homogeneous and to the Cartesian coordinates. They can be used independently from the chosen kernel model.
| Kernel::RT | v.hx () const | returns the homogeneous x coordinate. |
| Kernel::RT | v.hy () const | returns the homogeneous y coordinate. |
| Kernel::RT | v.hw () const | returns the homogenizing coordinate. |
Note that you do not loose information with the homogeneous representation, because the FieldNumberType is a quotient.
| Kernel::FT | v.x () const | returns the x-coordinate of v, that is hx/hw. |
| Kernel::FT | v.y () const | returns the y-coordinate of v, that is hy/hw. |
The following operations are for convenience and for compatibility with higher dimensional vectors. Again they come in a Cartesian and homogeneous flavor.
| Kernel::RT | v.homogeneous ( int i) const |
returns the i'th homogeneous coordinate of v, starting with 0.
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| Kernel::FT | v.cartesian ( int i) const |
returns the i'th
Cartesian
coordinate of v, starting at 0.
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| Kernel::FT | v.operator[] ( int i) const |
returns cartesian(i).
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| Cartesian_const_iterator | v.cartesian_begin () const | returns an iterator to the Cartesian coordinates of v, starting with the 0th coordinate. | ||
| Cartesian_const_iterator | v.cartesian_end () const | returns an off the end iterator to the Cartesian coordinates of v. | ||
| int | v.dimension () const | returns the dimension (the constant 2). | ||
| Direction_2<Kernel> | v.direction () const | returns the direction which passes through v. | ||
| Vector_2<Kernel> | v.transform ( Aff_transformation_2<Kernel> t) const | |||
| returns the vector obtained by applying t on v. | ||||
| Vector_2<Kernel> | v.perpendicular ( Orientation o) const | |||
| returns the vector perpendicular to v in clockwise or counterclockwise orientation. | ||||
The following operations can be applied to vectors:
| Vector_2<Kernel> | v.operator+ ( w) const | Addition. |
| Vector_2<Kernel> | v.operator- ( w) const | Subtraction. |
| Vector_2<Kernel> | v.operator- () const | returns the opposite vector. |
| Kernel::FT | v.operator* ( w) const | returns the scalar product (= inner product) of the two vectors. |
| Vector_2<Kernel> | operator* ( v, Kernel::RT s) | Multiplication with a scalar from the right. |
| Vector_2<Kernel> | operator* ( v, Kernel::FT s) | Multiplication with a scalar from the right. |
| Vector_2<Kernel> | operator* ( Kernel::RT s, v) | Multiplication with a scalar from the left. |
| Vector_2<Kernel> | operator* ( Kernel::FT s, v) | Multiplication with a scalar from the left. |
| Vector_2<Kernel> | v.operator/ ( Kernel::RT s) const | |
| Division by a scalar. | ||
| Kernel::FT | v.squared_length () const | returns the squared length of v. |