GEOM_FADE2D::Triangle2 Class Reference

Triangle. More...

#include <Triangle2.h>

Public Member Functions
	Triangle2 ()
	Constructor.
void	clearProperties ()
	Clear all corners and neighbor pointers.
double	getArea2D () const
	Get 2D Area. More...
Point2	getBarycenter () const
	Get the barycenter of a triangle. More...
Point2	getCircumcenter (CircumcenterQuality &ccq, bool bForceExact=false) const
	Get the circumcenter of the triangle. More...
void	getCorners (Point2 *&p0, Point2 *&p1, Point2 *&p2) const
	Get the 3 triangle corners.
std::pair< Point2, bool >	getDual (bool bForceExact=false) const
double	getInteriorAngle2D (int ith) const
	Get interior 2D angle. More...
int	getIntraTriangleIndex (const Point2 *p) const
	Get the index of p in the triangle. More...
int	getIntraTriangleIndex (const Point2 *p0, const Point2 *p1) const
	Get the index of (p0,p1) More...
int	getIntraTriangleIndex (const Triangle2 *pTriangle) const
	Get the neighbor index of pTriangle. More...
int	getMaxIndex () const
	Get the index of the largest edge.
double	getMaxSqEdgeLen2D () const
	Get the maximum squared 2D edge length.
int	getMinIndex () const
	Get the index of the smallest edge.
Triangle2 *	getOppositeTriangle (const int ith) const
	Get the i-th neighbor triangle. More...
double	getSquaredEdgeLength2D (int ith) const
	‍** More...
bool	hasOnEdge (int i, const Point2 &q) const
	Has point on edge. More...
bool	hasVertex (const Point2 &vtx) const
	Has vertex. More...
bool	hasVertex (const Point2 *pVtx) const
	Has vertex. More...
void	setOppTriangle (const int ith, Triangle2 *pTriangle)
	Set the i-th neighbor triangle. More...
void	setProperties (Point2 *pI, Point2 *pJ, Point2 *pK)
	Set all corners.
void	setPropertiesAndOppT (Point2 *pI, Point2 *pJ, Point2 *pK, Triangle2 *pNeig0, Triangle2 *pNeig1, Triangle2 *pNeig2)
	Set all corners and neighbor triangles.
void	setVertexPointer (const int ith, Point2 *pp)
	Set the i-th corner.

Protected Member Functions
double	computeArea (double l0, double l1, double l2) const
bool	getCC_inexact (double avgOffX, double avgOffY, Point2 &cc) const

Protected Attributes
Triangle2 *	aOppTriangles [3]
Point2 *	aVertexPointer [3]

Friends
std::ostream &	operator<< (std::ostream &stream, const Triangle2 &c)
void	registerTriangles (Triangle2 *fromTriangle, int ith, Triangle2 *toTriangle, int jth)

Detailed Description

Triangle2 is a triangle in the Fade_2D triangulation. It holds three Point2 pointers to its corners. The corners are numbered in counterclockwise order. We refer to these indices as intra-triangle-indices.

Each triangle has three neighbors which can be accessed through intra-triangle-indices: The i-th neighbor triangle of a certain triangle T is the one which shares an edge with T such that this edge does not include the i-th corner of T.

Indices and neighborships, tb is the 0-th neighbor of ta and ta is the 2nd neighbor of tb.

See also

TriangleAroundVertexIterator to find out how to access all triangles incident to a certain vertex.

Member Function Documentation

getArea2D()

double GEOM_FADE2D::Triangle2::getArea2D

(

)

const

Returns the 2D area of the triangle.

Note: The getArea() method is deprecated and replaced by getArea2D() to keep the names consistent.

getBarycenter()

Point2 GEOM_FADE2D::Triangle2::getBarycenter

(

)

const

Returns

the barycenter of the triangle.

getCircumcenter()

Point2 GEOM_FADE2D::Triangle2::getCircumcenter	(	CircumcenterQuality &	ccq,
		bool	bForceExact = false
	)		const

Parameters

[out]	ccq	returns the quality of the computed point and is one of CCQ_INEXACT, CCQ_EXACT and CCQ_OUT_OF_BOUNDS.
[in]	bForceExact	forces exact computation with multiple-precision arithmetic. When bForceExact=false, then the faster double-precision arithmetic is used for good shaped triangles.

Returns

the circumcenter of the triangle

Attention

Attention: The circumcenter of a nearly collinear triangle can have extremely large coordinates. Fade computes the circumcenter with multiple-precision artihmetic in this case but the result might nevertheless not be exact because it too large for double-precision coordinates. In such cases a finite point is returned and ccq returns CCQ_OUT_OF_BOUNDS. You can avoid such extreme numeric cases easily: Just insert four dummy vertices around the triangulation at coordinates 10 times larger than the domain of the data points because this restricts the Voronoi cells of the data points to this range.

getInteriorAngle2D()

double GEOM_FADE2D::Triangle2::getInteriorAngle2D

(

int

ith

)

const

Note: The getArea() method is deprecated and replaced by getInteriorAngle2D() to keep the names consistent.

Returns

the interior 2D angle at the ith vertex

getIntraTriangleIndex() [1/3]

int GEOM_FADE2D::Triangle2::getIntraTriangleIndex ( const Point2 *  p ) const

inline

Intra triangle index of a vertex pointer

Parameters

p	is a pointer to a vertex in *this

Returns

the intra-triangle-index 0,1 or 2 of p in *this

getIntraTriangleIndex() [2/3]

int GEOM_FADE2D::Triangle2::getIntraTriangleIndex ( const Point2 *  p0, const Point2 *  p1  ) const

inline

Returns

the index of the edge (p0,p1) in the triangle

getIntraTriangleIndex() [3/3]

int GEOM_FADE2D::Triangle2::getIntraTriangleIndex ( const Triangle2 *  pTriangle ) const

inline

pTriangle is the 0-th neighbor of *this

Parameters

pTriangle

is a neighbor triangle of *this.

Returns

the intra-triangle-index of the vertex in *this which is opposite (i.e., does not touch the neighbor) pTriangle.

getOppositeTriangle()

Triangle2 * GEOM_FADE2D::Triangle2::getOppositeTriangle ( const int  ith ) const

inline

Returns the i-th neighbor triangle, i.e. the one opposite to the i-th corner.

Neighbors of a triangle

Parameters

ith	is the intra-triangle-index of the opposite corner of *this

Returns

the i-th neighbor triangle, i.e. the one opposite to the i-th vertex or NULL if no neighbor triangle exists which is the case at the convex hull edges of the triangulation.

getSquaredEdgeLength2D()

double GEOM_FADE2D::Triangle2::getSquaredEdgeLength2D

(

int

ith

)

const

Method for internal use

Squared edge length

Returns the squared length of the ith edge.

hasOnEdge()

bool GEOM_FADE2D::Triangle2::hasOnEdge	(	int	i,
		const Point2 &	q
	)		const

Returns

if q is exactly on the i-th edge

hasVertex() [1/2]

bool GEOM_FADE2D::Triangle2::hasVertex

(

const Point2 &

vtx

)

const

Returns

if vtx is a corner of the triangle

hasVertex() [2/2]

bool GEOM_FADE2D::Triangle2::hasVertex

(

const Point2 *

pVtx

)

const

Returns

if pVtx is a corner of the triangle

setOppTriangle()

void GEOM_FADE2D::Triangle2::setOppTriangle ( const int  ith, Triangle2 *  pTriangle  )

inline

Make pTriangle the 0-th neighbor of *this

Parameters

ith	is the index of the corner of *this which does not touch pTriangle
pTriangle	is a pointer to the triangle which shares two corners with *this

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

• Triangle2.h