Half-edge class for navigating a DCEL mesh. More...

#include <EBGeometry_DCEL_Edge.hpp>

Collaboration diagram for EBGeometry::DCEL::EdgeT< T, Meta >:

[legend]

Public Types
using	Vec3 = Vec3T< T >
	Alias for vector type.

using	Vertex = VertexT< T, Meta >
	Alias for vertex type.

using	Edge = EdgeT< T, Meta >
	Alias for edge type.

using	Face = FaceT< T, Meta >
	Alias for face type.

using	VertexPtr = std::shared_ptr< Vertex >
	Alias for vertex pointer type.

using	EdgePtr = std::shared_ptr< Edge >
	Alias for edge pointer type.

using	FacePtr = std::shared_ptr< Face >
	Alias for face pointer type.

Public Member Functions
	EdgeT () noexcept=default
	Default constructor. Sets all pointers to zero and vectors to zero vectors.

	EdgeT (const Edge &a_otherEdge) noexcept
	Copy constructor.

	EdgeT (Edge &&a_otherEdge)=default
	Move constructor.

	EdgeT (const VertexPtr &a_vertex) noexcept
	Partial constructor. Calls the default constructor but sets the starting vertex.

	~EdgeT ()=default
	Destructor (does nothing)

Edge &	operator= (const Edge &a_otherEdge) noexcept
	Copy assignment operator.

Edge &	operator= (Edge &&a_otherEdge)=default
	Move assignment operator.

size_t	size () const noexcept
	Get size (in bytes) of this object.

void	define (const VertexPtr &a_vertex, const EdgePtr &a_pairEdge, const EdgePtr &a_nextEdge) noexcept
	Define function. Sets the starting vertex, edges, and normal vectors.

void	reconcile () noexcept
	Reconcile internal logic.

void	flipNormal () noexcept
	Flip surface normal.

void	setVertex (const VertexPtr &a_vertex) noexcept
	Set the starting vertex.

void	setPairEdge (const EdgePtr &a_pairEdge) noexcept
	Set the pair edge.

void	setNextEdge (const EdgePtr &a_nextEdge) noexcept
	Set the next edge.

void	setFace (const FacePtr &a_face) noexcept
	Set the pointer to this half-edge's face.

void	setMetaData (const Meta &a_metaData) noexcept
	Set the meta-data.

VertexPtr	getVertex () noexcept
	Get the starting vertex.

VertexPtr	getVertex () const noexcept
	Get the starting vertex (const overload).

VertexPtr	getOtherVertex () noexcept
	Get the end vertex.

VertexPtr	getOtherVertex () const noexcept
	Get the end vertex (const overload).

EdgePtr	getPairEdge () noexcept
	Get the pair edge.

EdgePtr	getPairEdge () const noexcept
	Get the pair edge (const overload).

EdgePtr	getNextEdge () noexcept
	Get the next edge.

EdgePtr	getNextEdge () const noexcept
	Get the next edge (const overload).

Vec3T< T >	computeNormal () const noexcept
	Compute the normal vector as the average of the face normals on both sides of this edge.

Vec3T< T > &	getNormal () noexcept
	Get modifiable normal vector.

const Vec3T< T > &	getNormal () const noexcept
	Get the stored normal vector.

FacePtr	getFace () noexcept
	Get this half-edge's face.

FacePtr	getFace () const noexcept
	Get this half-edge's face (const overload).

Meta &	getMetaData () noexcept
	Get meta-data.

const Meta &	getMetaData () const noexcept
	Get meta-data.

T	signedDistance (const Vec3 &a_x0) const noexcept
	Get the signed distance from a_x0 to this half-edge.

T	unsignedDistance2 (const Vec3 &a_x0) const noexcept
	Get the squared unsigned distance from a_x0 to this half-edge.

Protected Member Functions
T	projectPointToEdge (const Vec3 &a_x0) const noexcept
	Returns the parametric projection of a_x0 onto this edge.

Vec3T< T >	getX2X1 () const noexcept
	Get the vector pointing along this edge (from start to end vertex).

Protected Attributes
Vec3	m_normal = Vec3::zeros()
	Normal vector.

std::weak_ptr< Vertex >	m_vertex
	Starting vertex.

std::weak_ptr< Edge >	m_pairEdge
	Pair edge. See m_vertex for why this is a weak_ptr.

std::weak_ptr< Edge >	m_nextEdge
	Next edge. See m_vertex for why this is a weak_ptr.

std::weak_ptr< Face >	m_face
	Enclosing polygon face. See m_vertex for why this is a weak_ptr.

Meta	m_metaData {}
	Meta-data attached to this edge.

Detailed Description

template<class T, class Meta>
class EBGeometry::DCEL::EdgeT< T, Meta >

Half-edge class for navigating a DCEL mesh.

Class which represents a half-edge in a double-edge connected list (DCEL).

Template Parameters

T	Floating-point precision type.
Meta	User-defined metadata type.

This class is used in DCEL functionality which stores polygonal surfaces in a mesh. The information contain in an EdgeT object contains the necessary object for logically circulating the inside of a polygon face. This means that a polygon face has a double-connected list of half-edges which circulate the interior of the face. The EdgeT object is such a half-edge; it represents the outgoing half-edge from a vertex, located such that it can be logically represented as a half edge on the "inside" of a polygon face. It contains pointers to the polygon face, vertex, and next half edge It also contains a pointer to the "pair" half edge, i.e. the corresponding half-edge on the other face that shares this edge. Since this class is used with DCEL functionality and signed distance fields, this class also has a signed distance function and thus a "normal vector".

Note: The normal vector is outgoing, i.e. a point x is "outside" if the dot product between n and (x - x0) is positive.

Template Parameters

T	Floating-point precision.
Meta	Meta-data type stored per edge.

Constructor & Destructor Documentation

◆ EdgeT() [1/3]

template<class T , class Meta >

EBGeometry::DCEL::EdgeT< T, Meta >::EdgeT ( const Edge & a_otherEdge )

noexcept

Copy constructor.

Copies the normal vector and all four topology pointers (vertex, pair edge, next edge, face) from the other half-edge. Meta-data (m_metaData) is deliberately NOT copied – it default-constructs instead; use setMetaData() afterwards if it needs to be populated. Rationale: same as VertexT's copy constructor – these pointers are back-references into a specific mesh's topology (the objects they point to still reference the original edge, not this copy), so copying them wholesale is not topologically meaningful in general, but is occasionally useful (e.g. duplicating an edge's geometric/adjacency snapshot). operator=(const Edge&) has identical semantics.

Parameters

[in] a_otherEdge Other edge.

◆ EdgeT() [2/3]

template<class T , class Meta >

EBGeometry::DCEL::EdgeT< T, Meta >::EdgeT ( Edge && a_otherEdge )

default

Move constructor.

Unlike the copy constructor, this transfers the entire state (including m_metaData) from a_otherEdge, since moving relocates a single object's identity. Defaulted (memberwise move) rather than hand-written: explicitly defaulting is required here since the presence of a user-declared copy constructor would otherwise suppress the implicitly-generated move constructor. Not marked noexcept since Meta is an unconstrained template parameter whose move constructor is not guaranteed to be noexcept.

Parameters

[in,out] a_otherEdge Other edge.

◆ EdgeT() [3/3]

template<class T , class Meta >

EBGeometry::DCEL::EdgeT< T, Meta >::EdgeT ( const VertexPtr & a_vertex )

noexcept

Partial constructor. Calls the default constructor but sets the starting vertex.

Parameters

[in] a_vertex Starting vertex.

Member Function Documentation

◆ computeNormal()

template<class T , class Meta >

Vec3T< T > EBGeometry::DCEL::EdgeT< T, Meta >::computeNormal ( ) const

inlinenoexcept

Compute the normal vector as the average of the face normals on both sides of this edge.

Returns: Unit normal vector for this edge.

◆ define()

template<class T , class Meta >

void EBGeometry::DCEL::EdgeT< T, Meta >::define	(	const VertexPtr &	a_vertex,
		const EdgePtr &	a_pairEdge,
		const EdgePtr &	a_nextEdge
	)

inlinenoexcept

Define function. Sets the starting vertex, edges, and normal vectors.

Parameters

[in]	a_vertex	Starting vertex
[in]	a_pairEdge	Pair half-edge
[in]	a_nextEdge	Next half-edge

◆ getFace() [1/2]

template<class T , class Meta >

FacePtr EBGeometry::DCEL::EdgeT< T, Meta >::getFace ( ) const

inlinenoexcept

Get this half-edge's face (const overload).

Returns: Owning face, or nullptr.

◆ getFace() [2/2]

template<class T , class Meta >

FacePtr EBGeometry::DCEL::EdgeT< T, Meta >::getFace ( )

inlinenoexcept

Get this half-edge's face.

Returns: Owning face, or nullptr.

◆ getMetaData() [1/2]

template<class T , class Meta >

const Meta & EBGeometry::DCEL::EdgeT< T, Meta >::getMetaData ( ) const

inlinenoexcept

Get meta-data.

Returns: m_metaData

◆ getMetaData() [2/2]

template<class T , class Meta >

Meta & EBGeometry::DCEL::EdgeT< T, Meta >::getMetaData ( )

inlinenoexcept

Get meta-data.

Returns: m_metaData

◆ getNextEdge() [1/2]

template<class T , class Meta >

EdgePtr EBGeometry::DCEL::EdgeT< T, Meta >::getNextEdge ( ) const

inlinenoexcept

Get the next edge (const overload).

Returns: Next edge, or nullptr.

◆ getNextEdge() [2/2]

template<class T , class Meta >

EdgePtr EBGeometry::DCEL::EdgeT< T, Meta >::getNextEdge ( )

inlinenoexcept

Get the next edge.

Returns: Next edge, or nullptr.

◆ getNormal() [1/2]

template<class T , class Meta >

const Vec3T< T > & EBGeometry::DCEL::EdgeT< T, Meta >::getNormal ( ) const

inlinenoexcept

Get the stored normal vector.

Returns: Const reference to m_normal.

◆ getNormal() [2/2]

template<class T , class Meta >

Vec3T< T > & EBGeometry::DCEL::EdgeT< T, Meta >::getNormal ( )

inlinenoexcept

Get modifiable normal vector.

Returns: Reference to m_normal.

◆ getOtherVertex() [1/2]

template<class T , class Meta >

VertexPtr EBGeometry::DCEL::EdgeT< T, Meta >::getOtherVertex ( ) const

inlinenoexcept

Get the end vertex (const overload).

Returns: The next half-edge's starting vertex, or nullptr.

◆ getOtherVertex() [2/2]

template<class T , class Meta >

VertexPtr EBGeometry::DCEL::EdgeT< T, Meta >::getOtherVertex ( )

inlinenoexcept

Get the end vertex.

Returns: The next half-edge's starting vertex, or nullptr.

◆ getPairEdge() [1/2]

template<class T , class Meta >

EdgePtr EBGeometry::DCEL::EdgeT< T, Meta >::getPairEdge ( ) const

inlinenoexcept

Get the pair edge (const overload).

Returns: Pair edge, or nullptr.

◆ getPairEdge() [2/2]

template<class T , class Meta >

EdgePtr EBGeometry::DCEL::EdgeT< T, Meta >::getPairEdge ( )

inlinenoexcept

Get the pair edge.

Returns: Pair edge, or nullptr.

◆ getVertex() [1/2]

template<class T , class Meta >

VertexPtr EBGeometry::DCEL::EdgeT< T, Meta >::getVertex ( ) const

inlinenoexcept

Get the starting vertex (const overload).

Returns: Starting vertex, or nullptr.

◆ getVertex() [2/2]

template<class T , class Meta >

VertexPtr EBGeometry::DCEL::EdgeT< T, Meta >::getVertex ( )

inlinenoexcept

Get the starting vertex.

Returns a shared_ptr obtained by locking the internal weak_ptr (see the class-level

note on ownership). Returns nullptr if the vertex has been destroyed, which should not happen while the owning mesh is alive.

Returns: Starting vertex, or nullptr.

◆ getX2X1()

template<class T , class Meta >

Vec3T< T > EBGeometry::DCEL::EdgeT< T, Meta >::getX2X1 ( ) const

inlineprotectednoexcept

Get the vector pointing along this edge (from start to end vertex).

Returns: x2 - x1, where x1 = getVertex()->getPosition() and x2 = getOtherVertex()->getPosition().

◆ operator=() [1/2]

template<class T , class Meta >

Edge & EBGeometry::DCEL::EdgeT< T, Meta >::operator= ( const Edge & a_otherEdge )

noexcept

Copy assignment operator.

Has the same semantics as the copy constructor (including that m_metaData is not copied; use setMetaData() afterwards if it needs to be populated). See the copy constructor's documentation for details.

Parameters

[in] a_otherEdge Other edge.

Returns: Reference to (*this).

◆ operator=() [2/2]

template<class T , class Meta >

Edge & EBGeometry::DCEL::EdgeT< T, Meta >::operator= ( Edge && a_otherEdge )

default

Move assignment operator.

Has the same full-state-transfer semantics as the move constructor (defaulted memberwise move; see its documentation for why this must be defaulted explicitly).

Parameters

[in,out] a_otherEdge Other edge.

Returns: Reference to (*this).

◆ projectPointToEdge()

template<class T , class Meta >

T EBGeometry::DCEL::EdgeT< T, Meta >::projectPointToEdge ( const Vec3 & a_x0 ) const

inlineprotectednoexcept

Returns the parametric projection of a_x0 onto this edge.

Parametrizes the edge as x(t) = x1 + (x2-x1)*t and computes t such that x(t) is the closest point to a_x0. Returns t in (-inf, +inf); the point is on the segment when t in [0,1].

Parameters

[in] a_x0 Query point.

Returns: Projection parameter t.

◆ reconcile()

template<class T , class Meta >

void EBGeometry::DCEL::EdgeT< T, Meta >::reconcile ( )

inlinenoexcept

Reconcile internal logic.

Computes normal.

◆ setFace()

template<class T , class Meta >

void EBGeometry::DCEL::EdgeT< T, Meta >::setFace ( const FacePtr & a_face )

inlinenoexcept

Set the pointer to this half-edge's face.

Parameters

[in] a_face Face to associate with this half-edge.

◆ setMetaData()

template<class T , class Meta >

void EBGeometry::DCEL::EdgeT< T, Meta >::setMetaData ( const Meta & a_metaData )

inlinenoexcept

Set the meta-data.

Parameters

[in] a_metaData Meta-data.

◆ setNextEdge()

template<class T , class Meta >

void EBGeometry::DCEL::EdgeT< T, Meta >::setNextEdge ( const EdgePtr & a_nextEdge )

inlinenoexcept

Set the next edge.

Parameters

[in] a_nextEdge Next edge

◆ setPairEdge()

template<class T , class Meta >

void EBGeometry::DCEL::EdgeT< T, Meta >::setPairEdge ( const EdgePtr & a_pairEdge )

inlinenoexcept

Set the pair edge.

Parameters

[in] a_pairEdge Pair edge

◆ setVertex()

template<class T , class Meta >

void EBGeometry::DCEL::EdgeT< T, Meta >::setVertex ( const VertexPtr & a_vertex )

inlinenoexcept

Set the starting vertex.

Parameters

[in] a_vertex Starting vertex

◆ signedDistance()

template<class T , class Meta >

T EBGeometry::DCEL::EdgeT< T, Meta >::signedDistance ( const Vec3 & a_x0 ) const

inlinenoexcept

Get the signed distance from a_x0 to this half-edge.

Checks whether a_x0 projects onto the edge segment or past one of the end vertices. If it projects to a vertex, the signed distance to that vertex is returned. Otherwise the sign is determined from the edge normal.

Parameters

[in] a_x0 Query point.

Returns: Signed distance; positive on the normal side of the edge.

◆ size()

template<class T , class Meta >

size_t EBGeometry::DCEL::EdgeT< T, Meta >::size ( ) const

inlinenoexcept

Get size (in bytes) of this object.

Returns: Size in bytes of this edge object.

◆ unsignedDistance2()

template<class T , class Meta >

T EBGeometry::DCEL::EdgeT< T, Meta >::unsignedDistance2 ( const Vec3 & a_x0 ) const

inlinenoexcept

Get the squared unsigned distance from a_x0 to this half-edge.

Clamps the projection parameter to [0,1] so the closest point is always on the segment, then returns the squared distance. Faster than signedDistance().

Parameters

[in] a_x0 Query point.

Returns: Squared Euclidean distance to the closest point on the edge.

Member Data Documentation

◆ m_metaData

template<class T , class Meta >

Meta EBGeometry::DCEL::EdgeT< T, Meta >::m_metaData {}

protected

Meta-data attached to this edge.

Value-initialized so that every constructor leaves it in a defined state: for a fundamental Meta type (e.g. short, int), a member with no initializer and no explicit mention in a constructor's member-initializer list is left indeterminate, not zero.

◆ m_vertex

template<class T , class Meta >

std::weak_ptr<Vertex> EBGeometry::DCEL::EdgeT< T, Meta >::m_vertex

protected

Starting vertex.

Stored as a weak_ptr: the vertex is owned by the mesh's own vertex list, and a plain shared_ptr here (mirrored by the sibling m_pairEdge/m_nextEdge/m_face links, and by FaceT::m_halfEdge and VertexT::m_outgoingEdge) would form a reference cycle across the half-edge/face/vertex graph that shared_ptr's reference counting can never collect.

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

Source/EBGeometry_DCEL.hpp
Source/EBGeometry_DCEL_Edge.hpp

Public Types

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ EdgeT() [1/3]

◆ EdgeT() [2/3]

◆ EdgeT() [3/3]

Member Function Documentation

◆ computeNormal()

◆ define()

◆ getFace() [1/2]

◆ getFace() [2/2]

◆ getMetaData() [1/2]

◆ getMetaData() [2/2]

◆ getNextEdge() [1/2]

◆ getNextEdge() [2/2]

◆ getNormal() [1/2]

◆ getNormal() [2/2]

◆ getOtherVertex() [1/2]

◆ getOtherVertex() [2/2]

◆ getPairEdge() [1/2]

◆ getPairEdge() [2/2]

◆ getVertex() [1/2]

◆ getVertex() [2/2]

◆ getX2X1()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ projectPointToEdge()

◆ reconcile()

◆ setFace()

◆ setMetaData()

◆ setNextEdge()

◆ setPairEdge()

◆ setVertex()

◆ signedDistance()

◆ size()

◆ unsignedDistance2()

Member Data Documentation

◆ m_metaData

◆ m_vertex