gf::Polygon Class Reference

A convex polygon. More...

#include <gf/Polygon.h>

Public Member Functions
	Polygon ()=default
	Default constructor. More...
	Polygon (ArrayRef< Vector2f > points)
	Constructor from an array. More...
template<typename Iterator >
	Polygon (Iterator first, Iterator last)
	Constructor from points. More...
bool	isEmpty () const
	Check if the polygon is empty. More...
void	addPoint (Vector2f point)
	Add a point to the polygon. More...
std::size_t	getPointCount () const
	Get the number of points of the polygon. More...
Vector2f	getPoint (std::size_t index) const
	Get the i-th point of the polygon. More...
Vector2f	getCenter () const
	Get the center of the polygon. More...
Vector2f	getSupport (Vector2f direction, const Transform &transform) const
	Get the farthest point in a direction. More...
Vector2f	getSupport (Vector2f direction) const
	Get the farthest point in a direction. More...
const Vector2f *	begin () const
	Get an iterator to the first point. More...
const Vector2f *	end () const
	Get an iterator past the last point. More...
bool	isConvex () const
	Check if the polygon is convex. More...
Winding	getWinding () const
	Compute the winding of a convex polygon. More...
float	getArea () const
	Compute the area of the polygon. More...
void	applyTransform (const Matrix3f &mat)
	Apply a transformation to the polygon. More...
void	simplify (float distance=Epsilon)
	Simplify the polygon. More...

Detailed Description

A convex polygon.

Constructor & Destructor Documentation

Polygon() [1/3]

gf::Polygon::Polygon ( )

default

Default constructor.

Polygon() [2/3]

gf::Polygon::Polygon

(

ArrayRef< Vector2f >

points

)

Constructor from an array.

Parameters

points

The array of points

Polygon() [3/3]

template<typename Iterator >

gf::Polygon::Polygon ( Iterator  first, Iterator  last  )

inline

Constructor from points.

Parameters

first	Iterator to the first point
last	Iterator after the last point

Member Function Documentation

addPoint()

void gf::Polygon::addPoint

(

Vector2f

point

)

Add a point to the polygon.

Parameters

point

The point to add to the polygon

applyTransform()

void gf::Polygon::applyTransform

(

const Matrix3f &

mat

)

Apply a transformation to the polygon.

Parameters

mat	The transformation matrix

begin()

const Vector2f* gf::Polygon::begin

(

)

const

Get an iterator to the first point.

Returns

A pointer to the first point

See also

end()

end()

const Vector2f* gf::Polygon::end

(

)

const

Get an iterator past the last point.

Returns

A pointer past the last point

See also

begin()

getArea()

float gf::Polygon::getArea

(

)

const

Compute the area of the polygon.

Complexity: \( O(n) \)

Returns

The area of the polygon

getCenter()

Vector2f gf::Polygon::getCenter

(

)

const

Get the center of the polygon.

As the polygon is convex, the center is inside the polygon

Returns

The center of the polygon

getPoint()

Vector2f gf::Polygon::getPoint

(

std::size_t

index

)

const

Get the i-th point of the polygon.

Parameters

index

The index of the point

getPointCount()

std::size_t gf::Polygon::getPointCount

(

)

const

Get the number of points of the polygon.

Returns

The number of points of the polygon

getSupport() [1/2]

Vector2f gf::Polygon::getSupport	(	Vector2f	direction,
		const Transform &	transform
	)		const

Get the farthest point in a direction.

Parameters

direction	The direction to search (in world coordinates)
transform	The transformation of the polygon

Returns

The farthest point of the polygon in the given direction

getSupport() [2/2]

Vector2f gf::Polygon::getSupport

(

Vector2f

direction

)

const

Get the farthest point in a direction.

Parameters

direction

The direction to search

Returns

The farthest point of the polygon in the given direction

getWinding()

Winding gf::Polygon::getWinding

(

)

const

Compute the winding of a convex polygon.

Complexity: \( O(n) \)

Returns

The winding of the convex polygon

See also

gf::Winding, isConvex()

Curve orientation - Wikipedia

isConvex()

bool gf::Polygon::isConvex

(

)

const

Check if the polygon is convex.

This function should return true, otherwise you may have problems in other functions which assume that the polygon is convex.

This function does not handle self-intersecting polygons (yet).

Returns

True if the polygon is convex

isEmpty()

bool gf::Polygon::isEmpty

(

)

const

Check if the polygon is empty.

An empty polygon has no points.

Returns

True if the polygon is empty

simplify()

void gf::Polygon::simplify

(

float

distance = Epsilon

)

Simplify the polygon.

Parameters

distance

The maximum authorized distance between the original points and the simplified points