QGIS API Documentation 3.33.0-Master (bf22a165b3)
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QgsTriangulation Class Referenceabstract

Interface for Triangulation classes. More...

`#include <qgstriangulation.h>`

Inheritance diagram for QgsTriangulation: [legend]

## Public Types

enum  ForcedCrossBehavior { SnappingTypeVertex , DeleteFirst , InsertVertex }
Enumeration describing the behavior, if two forced lines cross. More...

## Public Member Functions

virtual ~QgsTriangulation ()=default

virtual void addLine (const QgsPointSequence &points, QgsInterpolator::SourceType lineType)=0

virtual int addPoint (const QgsPoint &point)=0
Adds a point to the triangulation.

virtual bool calcNormal (double x, double y, QgsPoint &result)=0
Calculates the normal at a point on the surface and assigns it to 'result'.

virtual bool calcPoint (double x, double y, QgsPoint &result)=0
Calculates x-, y and z-value of the point on the surface and assigns it to 'result'.

virtual void eliminateHorizontalTriangles ()=0
Eliminates the horizontal triangles by swapping.

virtual int oppositePoint (int p1, int p2)=0
Returns the number of the point opposite to the triangle points p1, p2 (which have to be on a halfedge).

virtual void performConsistencyTest ()=0
Performs a consistency check, remove this later.

virtual QgsPointpoint (int i) const =0
Returns a pointer to the point with number i.

virtual bool pointInside (double x, double y)=0
Returns `true`, if the point with coordinates x and y is inside the convex hull and `false` otherwise.

virtual QList< int > pointsAroundEdge (double x, double y)=0
Returns a value list with the numbers of the four points, which would be affected by an edge swap.

virtual int pointsCount () const =0
Returns the number of points.

virtual void ruppertRefinement ()=0
Adds points to make the triangles better shaped (algorithm of ruppert)

virtual bool saveTriangulation (QgsFeatureSink *sink, QgsFeedback *feedback=nullptr) const =0
Saves the triangulation features to a feature sink.

virtual void setForcedCrossBehavior (QgsTriangulation::ForcedCrossBehavior b)=0
Draws the points, edges and the forced lines.

virtual void setTriangleInterpolator (TriangleInterpolator *interpolator)=0
Sets an interpolator object.

virtual QList< int > surroundingTriangles (int pointno)=0
Returns a value list with the information of the triangles surrounding (counterclockwise) a point.

virtual bool swapEdge (double x, double y)=0
Reads the content of a taff-file.

virtual bool triangleVertices (double x, double y, QgsPoint &p1, int &n1, QgsPoint &p2, int &n2, QgsPoint &p3, int &n3)=0
Finds out in which triangle the point with coordinates x and y is and assigns the numbers of the vertices to 'n1', 'n2' and 'n3' and the vertices to 'p1', 'p2' and 'p3'.

virtual bool triangleVertices (double x, double y, QgsPoint &p1, QgsPoint &p2, QgsPoint &p3)=0
Finds out, in which triangle the point with coordinates x and y is and assigns the points at the vertices to 'p1', 'p2' and 'p3.

virtual QgsMesh triangulationToMesh (QgsFeedback *feedback=nullptr) const =0
Returns a QgsMesh corresponding to the triangulation.

virtual double xMax () const =0
Returns the largest x-coordinate value of the bounding box.

virtual double xMin () const =0
Returns the smallest x-coordinate value of the bounding box.

virtual double yMax () const =0
Returns the largest y-coordinate value of the bounding box.

virtual double yMin () const =0
Returns the smallest x-coordinate value of the bounding box.

## Static Public Member Functions

static QgsFields triangulationFields ()
Returns the fields output by features when calling saveTriangulation().

## Detailed Description

Interface for Triangulation classes.

Note
Not available in Python bindings.
Since
QGIS 3.16

Definition at line 41 of file qgstriangulation.h.

## ◆ ForcedCrossBehavior

Enumeration describing the behavior, if two forced lines cross.

Enumerator
SnappingTypeVertex

The second inserted forced line is snapped to the closest vertice of the first inserted forced line.

DeleteFirst

The status of the first inserted forced line is reset to that of a normal edge (so that the second inserted forced line remain and the first not)

InsertVertex

Definition at line 45 of file qgstriangulation.h.

## ◆ ~QgsTriangulation()

 virtual QgsTriangulation::~QgsTriangulation ( )
virtualdefault

## Member Function Documentation

 virtual void QgsTriangulation::addLine ( const QgsPointSequence & points, QgsInterpolator::SourceType lineType )
pure virtual

a break-, structure- or an isoline) to the triangulation, by specifying a list of source points.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

 virtual int QgsTriangulation::addPoint ( const QgsPoint & point )
pure virtual

Adds a point to the triangulation.

The point should have a z-value matching the value to interpolate.

Implemented in NormVecDecorator, QgsDualEdgeTriangulation, and TriDecorator.

## ◆ calcNormal()

 virtual bool QgsTriangulation::calcNormal ( double x, double y, QgsPoint & result )
pure virtual

Calculates the normal at a point on the surface and assigns it to 'result'.

Returns
`true` in case of success and `false` in case of failure

Implemented in NormVecDecorator, QgsDualEdgeTriangulation, and TriDecorator.

## ◆ calcPoint()

 virtual bool QgsTriangulation::calcPoint ( double x, double y, QgsPoint & result )
pure virtual

Calculates x-, y and z-value of the point on the surface and assigns it to 'result'.

Returns `true` in case of success and `false` in case of failure

Implemented in NormVecDecorator, QgsDualEdgeTriangulation, and TriDecorator.

## ◆ eliminateHorizontalTriangles()

 virtual void QgsTriangulation::eliminateHorizontalTriangles ( )
pure virtual

Eliminates the horizontal triangles by swapping.

Implemented in NormVecDecorator, QgsDualEdgeTriangulation, and TriDecorator.

## ◆ oppositePoint()

 virtual int QgsTriangulation::oppositePoint ( int p1, int p2 )
pure virtual

Returns the number of the point opposite to the triangle points p1, p2 (which have to be on a halfedge).

Returns -1 if point is a virtual point. Returns -10 if point crosses over edges.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ performConsistencyTest()

 virtual void QgsTriangulation::performConsistencyTest ( )
pure virtual

Performs a consistency check, remove this later.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ point()

 virtual QgsPoint * QgsTriangulation::point ( int i ) const
pure virtual

Returns a pointer to the point with number i.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ pointInside()

 virtual bool QgsTriangulation::pointInside ( double x, double y )
pure virtual

Returns `true`, if the point with coordinates x and y is inside the convex hull and `false` otherwise.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ pointsAroundEdge()

 virtual QList< int > QgsTriangulation::pointsAroundEdge ( double x, double y )
pure virtual

Returns a value list with the numbers of the four points, which would be affected by an edge swap.

This function is e.g. needed by NormVecDecorator to know the points, for which the normals have to be recalculated. The list has to be deleted by the code which calls this method

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ pointsCount()

 virtual int QgsTriangulation::pointsCount ( ) const
pure virtual

Returns the number of points.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ ruppertRefinement()

 virtual void QgsTriangulation::ruppertRefinement ( )
pure virtual

Adds points to make the triangles better shaped (algorithm of ruppert)

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ saveTriangulation()

 virtual bool QgsTriangulation::saveTriangulation ( QgsFeatureSink * sink, QgsFeedback * feedback = `nullptr` ) const
pure virtual

Saves the triangulation features to a feature sink.

The sink must be setup to accept LineString features, with fields matching those returned by triangulationFields().

Returns
`true` in case of success
triangulationFields()
Since
QGIS 3.0

Implemented in NormVecDecorator, and QgsDualEdgeTriangulation.

## ◆ setForcedCrossBehavior()

 virtual void QgsTriangulation::setForcedCrossBehavior ( QgsTriangulation::ForcedCrossBehavior b )
pure virtual

Draws the points, edges and the forced lines.

Sets the behavior of the triangulation in case of crossing forced lines

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ setTriangleInterpolator()

 virtual void QgsTriangulation::setTriangleInterpolator ( TriangleInterpolator * interpolator )
pure virtual

Sets an interpolator object.

Implemented in NormVecDecorator, QgsDualEdgeTriangulation, and TriDecorator.

## ◆ surroundingTriangles()

 virtual QList< int > QgsTriangulation::surroundingTriangles ( int pointno )
pure virtual

Returns a value list with the information of the triangles surrounding (counterclockwise) a point.

Four integer values describe a triangle, the first three are the number of the half edges of the triangle and the fourth is -10, if the third (and most counterclockwise) edge is a breakline, and -20 otherwise. Any virtual point needs to have the number -1

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ swapEdge()

 virtual bool QgsTriangulation::swapEdge ( double x, double y )
pure virtual

Reads the content of a taff-file.

Saves the content to a taff file Swaps the edge which is closest to the point with x and y coordinates (if this is possible)

Implemented in NormVecDecorator, QgsDualEdgeTriangulation, and TriDecorator.

## ◆ triangleVertices() [1/2]

 virtual bool QgsTriangulation::triangleVertices ( double x, double y, QgsPoint & p1, int & n1, QgsPoint & p2, int & n2, QgsPoint & p3, int & n3 )
pure virtual

Finds out in which triangle the point with coordinates x and y is and assigns the numbers of the vertices to 'n1', 'n2' and 'n3' and the vertices to 'p1', 'p2' and 'p3'.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ triangleVertices() [2/2]

 virtual bool QgsTriangulation::triangleVertices ( double x, double y, QgsPoint & p1, QgsPoint & p2, QgsPoint & p3 )
pure virtual

Finds out, in which triangle the point with coordinates x and y is and assigns the points at the vertices to 'p1', 'p2' and 'p3.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ triangulationFields()

 QgsFields QgsTriangulation::triangulationFields ( )
static

Returns the fields output by features when calling saveTriangulation().

These fields should be used when creating a suitable feature sink for saveTriangulation()

saveTriangulation()
Since
QGIS 3.0

Definition at line 18 of file qgstriangulation.cpp.

## ◆ triangulationToMesh()

 virtual QgsMesh QgsTriangulation::triangulationToMesh ( QgsFeedback * feedback = `nullptr` ) const
pure virtual

Returns a QgsMesh corresponding to the triangulation.

Since
QGIS 3.16

Implemented in NormVecDecorator, and QgsDualEdgeTriangulation.

## ◆ xMax()

 virtual double QgsTriangulation::xMax ( ) const
pure virtual

Returns the largest x-coordinate value of the bounding box.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ xMin()

 virtual double QgsTriangulation::xMin ( ) const
pure virtual

Returns the smallest x-coordinate value of the bounding box.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ yMax()

 virtual double QgsTriangulation::yMax ( ) const
pure virtual

Returns the largest y-coordinate value of the bounding box.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

## ◆ yMin()

 virtual double QgsTriangulation::yMin ( ) const
pure virtual

Returns the smallest x-coordinate value of the bounding box.

Implemented in QgsDualEdgeTriangulation, and TriDecorator.

The documentation for this class was generated from the following files:
• /build/qgis-3.33.0+git20230922+bf22a165b3+99sid/src/analysis/interpolation/qgstriangulation.h
• /build/qgis-3.33.0+git20230922+bf22a165b3+99sid/src/analysis/interpolation/qgstriangulation.cpp