Represents a polygon defined by an array of points. More...

#include </home/docs/checkouts/readthedocs.org/user_builds/axom/checkouts/develop/src/axom/primal/geometry/Polygon.hpp>

Public Types
using	PointType = Point< T, NDIMS >

using	VectorType = Vector< T, NDIMS >

Public Member Functions
	Polygon ()
	Default constructor for an empty polygon. More...

	Polygon (int numExpectedVerts)
	Constructor for an empty polygon that reserves space for the given number of vertices. More...

	Polygon (const axom::Array< PointType > &vertices)
	Constructor for a polygon with the given vertices. More...

int	numVertices () const
	Return the number of vertices in the polygon. More...

void	addVertex (const PointType &pt)
	Appends a vertex to the list of vertices. More...

void	clear ()
	Clears the list of vertices. More...

PointType &	operator[] (int idx)
	Retrieves the vertex at index idx. More...

const PointType &	operator[] (int idx) const
	Retrieves the vertex at index idx. More...

template<int TDIM = NDIMS>
std::enable_if< TDIM==3, VectorType >::type	normal () const
	Robustly returns the normal of the polygon (not normalized) More...

PointType	vertexMean () const
	Computes the average of the polygon's vertex positions. More...

template<int TDIM = NDIMS>
std::enable_if< TDIM==3, double >::type	area () const
	Returns the area of the polygon (3D specialization) More...

template<int TDIM = NDIMS>
std::enable_if< TDIM==2, double >::type	area () const
	Returns the area of a planar polygon (2D specialization) More...

template<int TDIM = NDIMS>
std::enable_if< TDIM==2, double >::type	signedArea () const
	Returns the signed area of a 2D polygon. More...

std::ostream &	print (std::ostream &os) const
	Simple formatted print of a polygon instance. More...

bool	isValid () const
	Simple check for validity of a polygon. More...

Detailed Description

template<typename T, int NDIMS>
class axom::primal::Polygon< T, NDIMS >

Represents a polygon defined by an array of points.

Template Parameters

T	the coordinate type, e.g., double, float, etc.
NDIMS	the number of dimensions

Note: The polygon vertices should be ordered in a counter clockwise orientation with respect to the polygon's desired normal vector

Member Typedef Documentation

◆ PointType

template<typename T , int NDIMS>

using axom::primal::Polygon< T, NDIMS >::PointType = Point<T, NDIMS>

◆ VectorType

template<typename T , int NDIMS>

using axom::primal::Polygon< T, NDIMS >::VectorType = Vector<T, NDIMS>

Constructor & Destructor Documentation

◆ Polygon() [1/3]

template<typename T , int NDIMS>

axom::primal::Polygon< T, NDIMS >::Polygon ( )

inline

Default constructor for an empty polygon.

◆ Polygon() [2/3]

template<typename T , int NDIMS>

axom::primal::Polygon< T, NDIMS >::Polygon ( int numExpectedVerts )

inlineexplicit

Constructor for an empty polygon that reserves space for the given number of vertices.

Parameters

[in] numExpectedVerts number of vertices for which to reserve space

Precondition: numExpectedVerts is not negative

References axom::Array< T, DIM, SPACE >::reserve(), and SLIC_ASSERT.

◆ Polygon() [3/3]

template<typename T , int NDIMS>

axom::primal::Polygon< T, NDIMS >::Polygon ( const axom::Array< PointType > & vertices )

inline

Constructor for a polygon with the given vertices.

Member Function Documentation

◆ numVertices()

template<typename T , int NDIMS>

int axom::primal::Polygon< T, NDIMS >::numVertices ( ) const

inline

Return the number of vertices in the polygon.

References axom::Array< T, DIM, SPACE >::size().

◆ addVertex()

template<typename T , int NDIMS>

void axom::primal::Polygon< T, NDIMS >::addVertex ( const PointType & pt )

inline

Appends a vertex to the list of vertices.

References axom::Array< T, DIM, SPACE >::push_back().

◆ clear()

template<typename T , int NDIMS>

void axom::primal::Polygon< T, NDIMS >::clear ( )

inline

Clears the list of vertices.

References axom::Array< T, DIM, SPACE >::clear().

◆ operator[]() [1/2]

template<typename T , int NDIMS>

PointType& axom::primal::Polygon< T, NDIMS >::operator[] ( int idx )

inline

Retrieves the vertex at index idx.

◆ operator[]() [2/2]

template<typename T , int NDIMS>

const PointType& axom::primal::Polygon< T, NDIMS >::operator[] ( int idx ) const

inline

Retrieves the vertex at index idx.

◆ normal()

template<typename T , int NDIMS>

template<int TDIM = NDIMS>

std::enable_if<TDIM == 3, VectorType>::type axom::primal::Polygon< T, NDIMS >::normal ( ) const

inline

Robustly returns the normal of the polygon (not normalized)

Precondition: This function is only valid when NDIMS = 3 and the polygon is valid

Returns: normal polygon normal vector

References axom::primal::Vector< T, NDIMS >::cross_product(), axom::primal::Polygon< T, NDIMS >::isValid(), axom::primal::Polygon< T, NDIMS >::numVertices(), and SLIC_ASSERT.

◆ vertexMean()

template<typename T , int NDIMS>

PointType axom::primal::Polygon< T, NDIMS >::vertexMean ( ) const

inline

Computes the average of the polygon's vertex positions.

Returns: A point at the mean of the polygon's vertices

Precondition: polygon.isValid() is true

References axom::primal::Point< T, NDIMS >::array(), axom::primal::Polygon< T, NDIMS >::isValid(), axom::primal::Polygon< T, NDIMS >::numVertices(), and SLIC_ASSERT.

◆ area() [1/2]

template<typename T , int NDIMS>

template<int TDIM = NDIMS>

std::enable_if<TDIM == 3, double>::type axom::primal::Polygon< T, NDIMS >::area ( ) const

inline

Returns the area of the polygon (3D specialization)

The algorithm sums up contributions from triangles defined by each edge of the polygon and a local origin (at the Polygon's vertexMean()). The algorithm assumes a planar polygon embedded in 3D, however it will return a value for non-planar polygons.

The area is always non-negative since 3D polygons do not have a unique orientation.

References axom::utilities::abs(), axom::primal::Vector< T, NDIMS >::cross_product(), axom::primal::Vector< T, NDIMS >::norm(), axom::primal::Polygon< T, NDIMS >::numVertices(), and axom::primal::Polygon< T, NDIMS >::vertexMean().

◆ area() [2/2]

template<typename T , int NDIMS>

template<int TDIM = NDIMS>

std::enable_if<TDIM == 2, double>::type axom::primal::Polygon< T, NDIMS >::area ( ) const

inline

Returns the area of a planar polygon (2D specialization)

The area is always non-negative.

See also: signedArea()

References axom::utilities::abs(), and axom::primal::Polygon< T, NDIMS >::signedArea().

◆ signedArea()

template<typename T , int NDIMS>

template<int TDIM = NDIMS>

std::enable_if<TDIM == 2, double>::type axom::primal::Polygon< T, NDIMS >::signedArea ( ) const

inline

Returns the signed area of a 2D polygon.

The signed area accounts for the orientation of the polygon. It is positive when the vertices are oriented counter-clockwise and negative when the vertices are oriented clockwise.

Note: Signed area is only defined in 2D.

See also: area()

References axom::primal::Polygon< T, NDIMS >::numVertices().

◆ print()

template<typename T , int NDIMS>

std::ostream& axom::primal::Polygon< T, NDIMS >::print ( std::ostream & os ) const

inline

Simple formatted print of a polygon instance.

Parameters

os	The output stream to write to

Returns: A reference to the modified ostream

References axom::primal::Polygon< T, NDIMS >::numVertices().

◆ isValid()

template<typename T , int NDIMS>

bool axom::primal::Polygon< T, NDIMS >::isValid ( ) const

inline

Simple check for validity of a polygon.

Initial check is that the polygon has three or more vertices

Returns: True, if the polygon is valid, False otherwise

References axom::Array< T, DIM, SPACE >::size().

The documentation for this class was generated from the following file:

/home/docs/checkouts/readthedocs.org/user_builds/axom/checkouts/develop/src/axom/primal/geometry/Polygon.hpp

Public Types

Public Member Functions

Detailed Description

template<typename T, int NDIMS> class axom::primal::Polygon< T, NDIMS >

Member Typedef Documentation

◆ PointType

◆ VectorType

Constructor & Destructor Documentation

◆ Polygon() [1/3]

◆ Polygon() [2/3]

◆ Polygon() [3/3]

Member Function Documentation

◆ numVertices()

◆ addVertex()

◆ clear()

◆ operator[]() [1/2]

◆ operator[]() [2/2]

◆ normal()

◆ vertexMean()

◆ area() [1/2]

◆ area() [2/2]

◆ signedArea()

◆ print()

◆ isValid()

template<typename T, int NDIMS>
class axom::primal::Polygon< T, NDIMS >