Poly_CoherentTriangulation Class Reference

#include <Poly_CoherentTriangulation.hxx>

Inheritance diagram for Poly_CoherentTriangulation:

[legend]

Data Structures
class	IteratorOfLink
class	IteratorOfNode
class	IteratorOfTriangle
struct	TwoIntegers
	Couple of integer indices (used in RemoveDegenerated()). More...
Public Member Functions
	Poly_CoherentTriangulation (const Handle_NCollection_BaseAllocator &theAlloc=0L)
	Poly_CoherentTriangulation (const Handle_Poly_Triangulation &theTriangulation, const Handle_NCollection_BaseAllocator &theAlloc=0L)
virtual	~Poly_CoherentTriangulation ()
Handle_Poly_Triangulation	GetTriangulation () const
Standard_Boolean	RemoveDegenerated (const Standard_Real theTol, NCollection_List< TwoIntegers > *pLstRemovedNode=0L)
Standard_Boolean	GetFreeNodes (NCollection_List< Standard_Integer > &lstNodes) const
Standard_Integer	MaxNode () const
Standard_Integer	MaxTriangle () const
void	SetDeflection (const Standard_Real theDefl)
Standard_Real	Deflection () const
Standard_Integer	SetNode (const gp_XYZ &thePnt, const Standard_Integer iN=-1)
const Poly_CoherentNode &	Node (const Standard_Integer i) const
Poly_CoherentNode &	ChangeNode (const Standard_Integer i)
Standard_Integer	NNodes () const
const Poly_CoherentTriangle &	Triangle (const Standard_Integer i) const
Standard_Integer	NTriangles () const
Standard_Integer	NLinks () const
Standard_Boolean	RemoveTriangle (Poly_CoherentTriangle &theTr)
void	RemoveLink (Poly_CoherentLink &theLink)
Poly_CoherentTriangle *	AddTriangle (const Standard_Integer iNode0, const Standard_Integer iNode1, const Standard_Integer iNode2)
Standard_Boolean	ReplaceNodes (Poly_CoherentTriangle &theTriangle, const Standard_Integer iNode0, const Standard_Integer iNode1, const Standard_Integer iNode2)
Poly_CoherentLink *	AddLink (const Poly_CoherentTriangle &theTri, const Standard_Integer theConn)
Standard_Boolean	FindTriangle (const Poly_CoherentLink &theLink, const Poly_CoherentTriangle *pTri[2]) const
Standard_Integer	ComputeLinks ()
void	ClearLinks ()
const Handle_NCollection_BaseAllocator &	Allocator () const
Handle_Poly_CoherentTriangulation	Clone (const Handle_NCollection_BaseAllocator &theAlloc) const
void	Dump (Standard_OStream &) const
Protected Attributes
NCollection_Vector < Poly_CoherentTriangle >	myTriangles
NCollection_Vector < Poly_CoherentNode >	myNodes
NCollection_Vector < Poly_CoherentLink >	myLinks
Handle_NCollection_BaseAllocator	myAlloc
Standard_Real	myDeflection

---

Detailed Description

Triangulation structure that allows to:

• Store the connectivity of each triangle with up to 3 neighbouring ones and with the corresponding 3rd nodes on them,
• Store the connectivity of each node with all triangles that share this node
• Add nodes and triangles to the structure,
• Find all triangles sharing a single or a couple of nodes
• Remove triangles from structure
• Optionally create Links between pairs of nodes according to the current triangulation.
• Convert from/to Poly_Triangulation structure.

This class is useful for algorithms that need to analyse and/or edit a triangulated mesh -- for example for mesh refining. The connectivity model follows the idea that all Triangles in a mesh should have coherent orientation like on a surface of a solid body. Connections between more than 2 triangles are not suppoorted.

Architecture

The data types used in this structure are:

• Poly_CoherentNode: Inherits go_XYZ therefore provides the full public API of gp_XYZ. Contains references to all incident triangles. You can add new nodes but you cannot remove existing ones. However each node that has no referenced triangle is considered as "free" (use the method IsFreeNode() to check this). Free nodes are not available to further processing, particularly they are not exported in Poly_Triangulation.
• Poly_CoherentTriangle: Main data type. Refers three Nodes, three connected Triangles, three opposite (connected) Nodes and three Links. If there is boundary then 1, 2 or 3 references to Triangles/connected Nodes/Links are assigned to NULL (for pointers) or -1 (for integer node index).
  You can find a triangle by one node using its triangle iterator or by two nodes - creating a temporary Poly_CoherentLink and calling the method FindTriangle().
  Triangles can be removed but they are never deleted from the containing array. Removed triangles have all nodes equal to -1. You can use the method IsEmpty() to check that.
• Poly_CoherentLink: Auxiliary data type. Normally the array of Links is empty, because for many algorithms it is sufficient to define only Triangles. You can explicitly create the Links at least once, calling the method ComputeLinks(). Each Link is oriented couple of Poly_CoherentNode (directed to the ascending Node index). It refers two connected triangulated Nodes - on the left and on the right, therefore a Poly_CoherentLink instance refers the full set of nodes that constitute a couple of connected Triangles. A boundary Link has either the first (left) or the second (right) connected node index equal to -1.
  When the array of Links is created, all subsequent calls to AddTriangle and RemoveTriangle try to preserve the connectivity Triangle-Link in addition to the connectivity Triangle-Triangle. Particularly, new Links are created by method AddTriangle() and existing ones are removed by method RemoveTriangle(), in each case whenever necessary.
  Similarly to Poly_CoherentTriangle, a Link can be removed but not destroyed separately from others. Removed Link can be recogniosed using the method IsEmpty(). To destroy all Links, call the method ClearLinks(), this method also nullifies Link references in all Triangles. All objects (except for free Nodes and empty Triangles and Links) can be visited by the corresponding Iterator. Direct access is provided only for Nodes (needed to resolve Node indexed commonly used as reference). Triangles and Links can be retrieved by their index only internally, the public API provides only references or pointers to C++ objects. If you need a direct access to Triangles and Links, you can subclass Poly_CoherentTriangulation and use the protected API for your needs.
  Memory management: All data objects are stored in NCollection_Vector containers that prove to be efficient for the performance. In addition references to triangles are stored in ring lists, with an instance of such list per Poly_CoherentNode. These lists are allocated in a memory allocator that is provided in the constructor of Poly_CoherentTriangulation. By default the standard OCCT allocator (aka NCollection_BaseAllocator) is used. But if you need to increase the performance you can use NCollection_IncAllocator instead.

---

Constructor & Destructor Documentation

Poly_CoherentTriangulation::Poly_CoherentTriangulation

(

const Handle_NCollection_BaseAllocator &

theAlloc = 0L

)

Empty constructor.

Poly_CoherentTriangulation::Poly_CoherentTriangulation	(	const Handle_Poly_Triangulation &	theTriangulation,
		const Handle_NCollection_BaseAllocator &	theAlloc = 0L
	)

Constructor. It does not create Links, you should call ComputeLinks following this constructor if you need these links.

virtual Poly_CoherentTriangulation::~Poly_CoherentTriangulation

(

)

[virtual]

Destructor.

---

Member Function Documentation

Poly_CoherentLink* Poly_CoherentTriangulation::AddLink	(	const Poly_CoherentTriangle &	theTri,
		const Standard_Integer	theConn
	)

Add a single link to triangulation, based on a triangle and its side index. This method does not check for coincidence with already present links.

Parameters:

	theTri	Triangle that contains the link to be added.
	theConn	Index of the side (i.e., 0, 1 0r 2) defining the added link.

Poly_CoherentTriangle* Poly_CoherentTriangulation::AddTriangle	(	const Standard_Integer	iNode0,
		const Standard_Integer	iNode1,
		const Standard_Integer	iNode2
	)

Add a triangle to the triangulation.

Returns:

Pointer to the added triangle instance or NULL if an error occurred.

const Handle_NCollection_BaseAllocator& Poly_CoherentTriangulation::Allocator

(

)

const [inline]

Query the allocator of elements, this allocator can be used for other objects

Poly_CoherentNode& Poly_CoherentTriangulation::ChangeNode

(

const Standard_Integer

i

)

[inline]

Get the node at the given index 'i'.

void Poly_CoherentTriangulation::ClearLinks

(

)

Clear all Links data from the Triangulation data.

Handle_Poly_CoherentTriangulation Poly_CoherentTriangulation::Clone

(

const Handle_NCollection_BaseAllocator &

theAlloc

)

const

Create a copy of this Triangulation, using the given allocator.

Standard_Integer Poly_CoherentTriangulation::ComputeLinks

(

)

(Re)Calculate all links in this Triangulation.

Standard_Real Poly_CoherentTriangulation::Deflection

(

)

const [inline]

Query the Deflection parameter (default value 0. -- if never initialized)

void Poly_CoherentTriangulation::Dump

(

Standard_OStream &

)

const

Debugging output.

Standard_Boolean Poly_CoherentTriangulation::FindTriangle	(	const Poly_CoherentLink &	theLink,
		const Poly_CoherentTriangle *	pTri[2]
	)			const

Find one or two triangles that share the given couple of nodes.

Parameters:

	theLink	Link (in fact, just a couple of nodes) on which the triangle is searched.
	pTri	[out] Array of two pointers to triangle. pTri[0] stores the triangle to the left of the link, while pTri[1] stores the one to the right of the link.

Returns:

True if at least one triangle is found and output as pTri.

Standard_Boolean Poly_CoherentTriangulation::GetFreeNodes

(

NCollection_List< Standard_Integer > &

lstNodes

)

const

Create a list of free nodes. These nodes may appear as a result of any custom mesh decimation or RemoveDegenerated() call. This analysis is necessary if you support additional data structures based on the triangulation (e.g., edges on the surface boundary).

Parameters:

lstNodes

[out] List that receives the indices of free nodes.

Handle_Poly_Triangulation Poly_CoherentTriangulation::GetTriangulation

(

)

const

Create an instance of Poly_Triangulation from this object.

Standard_Integer Poly_CoherentTriangulation::MaxNode

(

)

const [inline]

Query the index of the last node in the triangulation

Standard_Integer Poly_CoherentTriangulation::MaxTriangle

(

)

const [inline]

Query the index of the last triangle in the triangulation

Standard_Integer Poly_CoherentTriangulation::NLinks

(

)

const

Query the total number of active Links.

Standard_Integer Poly_CoherentTriangulation::NNodes

(

)

const

Query the total number of active nodes (i.e. nodes used by 1 or more triangles)

const Poly_CoherentNode& Poly_CoherentTriangulation::Node

(

const Standard_Integer

i

)

const [inline]

Get the node at the given index 'i'.

Standard_Integer Poly_CoherentTriangulation::NTriangles

(

)

const

Query the total number of active triangles (i.e. triangles that refer nodes, non-empty ones)

Standard_Boolean Poly_CoherentTriangulation::RemoveDegenerated	(	const Standard_Real	theTol,
		NCollection_List< TwoIntegers > *	pLstRemovedNode = 0L
	)

Find and remove degenerated triangles in Triangulation.

Parameters:

	theTol	Tolerance for the degeneration case. If any two nodes of a triangle have the distance less than this tolerance, this triangle is considered degenerated and therefore removed by this method.
	pLstRemovedNode	Optional parameter. If defined, then it will receive the list of arrays where the first number is the index of removed node and the seond - the index of remaining node to which the mesh was reconnected.

void Poly_CoherentTriangulation::RemoveLink

(

Poly_CoherentLink &

theLink

)

Removal of a single link from the triangulation.

Standard_Boolean Poly_CoherentTriangulation::RemoveTriangle

(

Poly_CoherentTriangle &

theTr

)

Removal of a single triangle from the triangulation.

Standard_Boolean Poly_CoherentTriangulation::ReplaceNodes	(	Poly_CoherentTriangle &	theTriangle,
		const Standard_Integer	iNode0,
		const Standard_Integer	iNode1,
		const Standard_Integer	iNode2
	)

Replace nodes in the given triangle.

Returns:

True if operation succeeded.

void Poly_CoherentTriangulation::SetDeflection

(

const Standard_Real

theDefl

)

[inline]

Set the Deflection value as the parameter of the given triangulation.

Standard_Integer Poly_CoherentTriangulation::SetNode	(	const gp_XYZ &	thePnt,
		const Standard_Integer	iN = -1
	)

Initialize a node

Parameters:

	thePoint	3D Coordinates of the node.
	iN	Index of the node. If negative (default), the node is added to the end of the current array of nodes.

Returns:

Index of the added node.

const Poly_CoherentTriangle& Poly_CoherentTriangulation::Triangle

(

const Standard_Integer

i

)

const [inline]

Get the triangle at the given index 'i'.

---

Field Documentation

Handle_NCollection_BaseAllocator Poly_CoherentTriangulation::myAlloc [protected]

Standard_Real Poly_CoherentTriangulation::myDeflection [protected]

NCollection_Vector<Poly_CoherentLink> Poly_CoherentTriangulation::myLinks [protected]

NCollection_Vector<Poly_CoherentNode> Poly_CoherentTriangulation::myNodes [protected]

NCollection_Vector<Poly_CoherentTriangle> Poly_CoherentTriangulation::myTriangles [protected]

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

• Poly_CoherentTriangulation.hxx