QgsTriangle class

Triangle geometry type.

Contents

Base classes

class QgsPolygon
Polygon geometry type.

Constructors, destructors, conversion operators

QgsTriangle(const QgsPoint& p1, const QgsPoint& p2, const QgsPoint& p3)
Construct a QgsTriangle from three QgsPointV2.
QgsTriangle(const QgsPointXY& p1, const QgsPointXY& p2, const QgsPointXY& p3) explicit
Construct a QgsTriangle from three QgsPoint.
QgsTriangle(QPointF p1, QPointF p2, QPointF p3) explicit
Construct a QgsTriangle from three QPointF.

Public functions

void addInteriorRing(QgsCurve* ring) override
Inherited method not used. You cannot add an interior ring into a triangle.
auto altitudes() const -> QVector<QgsLineString>
An altitude is a segment (defined by a QgsLineString) from a vertex to the opposite side (or, if necessary, to the extension of the opposite side).
auto angles() const -> QVector<double>
Returns the three angles of the triangle.
auto asGml3(QDomDocument& doc, int precision = 17, const QString& ns = "gml", QgsAbstractGeometry::AxisOrder axisOrder = QgsAbstractGeometry::AxisOrder::XY) const -> QDomElement override
Returns a GML3 representation of the geometry.
auto bisectors(double lengthTolerance = 0.0001) const -> QVector<QgsLineString>
The segment (defined by a QgsLineString) returned bisect the angle of a vertex to the opposite side.
auto boundary() const -> QgsCurve* override
Returns the closure of the combinatorial boundary of the geometry (ie the topological boundary of the geometry).
auto cast(const QgsAbstractGeometry* geom) const -> const QgsTriangle*
Cast the geom to a QgsTriangle.
auto circumscribedCenter() const -> QgsPoint
Center of the circumscribed circle of the triangle.
auto circumscribedCircle() const -> QgsCircle
Circumscribed circle of the triangle.
auto circumscribedRadius() const -> double
Radius of the circumscribed circle of the triangle.
void clear() override
Clears the geometry, ie reset it to a null geometry.
auto clone() const -> QgsTriangle* override
Clones the geometry by performing a deep copy.
auto createEmptyWithSameType() const -> QgsTriangle* override
Creates a new geometry with the same class and same WKB type as the original and transfers ownership.
auto deleteVertex(QgsVertexId position) -> bool override
Inherited method not used. You cannot delete or insert a vertex directly. Returns always false.
auto fromWkb(QgsConstWkbPtr& wkb) -> bool override
Sets the geometry from a WKB string.
auto fromWkt(const QString& wkt) -> bool override
Sets the geometry from a WKT string.
auto geometryType() const -> QString override
Returns a unique string representing the geometry type.
auto inscribedCenter() const -> QgsPoint
Center of the inscribed circle of the triangle.
auto inscribedCircle() const -> QgsCircle
Inscribed circle of the triangle.
auto inscribedRadius() const -> double
Radius of the inscribed circle of the triangle.
auto insertVertex(QgsVertexId position, const QgsPoint& vertex) -> bool override
Inherited method not used. You cannot delete or insert a vertex directly. Returns always false.
auto isDegenerate() -> bool
Convenient method checking if the geometry is degenerate (have duplicate or colinear point(s)).
auto isEquilateral(double lengthTolerance = 0.0001) const -> bool
Is the triangle equilateral (three sides with the same length)?
auto isIsocele(double lengthTolerance = 0.0001) const -> bool
Is the triangle isocele (two sides with the same length)?
auto isRight(double angleTolerance = 0.0001) const -> bool
Is the triangle right-angled?
auto isScalene(double lengthTolerance = 0.0001) const -> bool
Is the triangle scalene (all sides have different lengths)?
auto lengths() const -> QVector<double>
Returns the three lengths of the triangle.
auto medial() const -> QgsTriangle
Medial (or midpoint) triangle of a triangle ABC is the triangle with vertices at the midpoints of the triangle's sides.
auto medians() const -> QVector<QgsLineString>
A median is a segment (defined by a QgsLineString) from a vertex to the midpoint of the opposite side.
auto moveVertex(QgsVertexId position, const QgsPoint& newPos) -> bool override
Moves a vertex within the geometry.
auto orthocenter(double lengthTolerance = 0.0001) const -> QgsPoint
An orthocenter is the point of intersection of the altitudes of a triangle.
void setExteriorRing(QgsCurve* ring) override
Sets the exterior ring of the polygon.
void setInteriorRings(const QVector<QgsCurve*>& rings) deleted
Inherited method not used.
auto surfaceToPolygon() const -> QgsPolygon* override
Gets a polygon representation of this surface.
auto toCurveType() const -> QgsCurvePolygon* override
Returns the geometry converted to the more generic curve type QgsCurvePolygon.
auto vertexAt(int atVertex) const -> QgsPoint
Returns coordinates of a vertex.

Function documentation

QgsTriangle::QgsTriangle(const QgsPoint& p1, const QgsPoint& p2, const QgsPoint& p3)

Construct a QgsTriangle from three QgsPointV2.

Parameters
p1 first point
p2 second point
p3 third point

QgsTriangle::QgsTriangle(const QgsPointXY& p1, const QgsPointXY& p2, const QgsPointXY& p3) explicit

Construct a QgsTriangle from three QgsPoint.

Parameters
p1 first point
p2 second point
p3 third point

QgsTriangle::QgsTriangle(QPointF p1, QPointF p2, QPointF p3) explicit

Construct a QgsTriangle from three QPointF.

Parameters
p1 first point
p2 second point
p3 third point

QVector<QgsLineString> QgsTriangle::altitudes() const

An altitude is a segment (defined by a QgsLineString) from a vertex to the opposite side (or, if necessary, to the extension of the opposite side).

Returns

Three altitudes from this triangle. An empty list is returned for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
[alt.asWkt() for alt in tri.altitudes()]
# ['LineString (0 0, 0 5)', 'LineString (0 5, 2.5 2.5)', 'LineString (5 5, 0 5)']
QgsTriangle().altitudes()
# []

QVector<double> QgsTriangle::angles() const

Returns the three angles of the triangle.

Returns

Angles in radians of triangle ABC where angle BAC is at 0, angle ABC is at 1, angle BCA is at 2. An empty list is returned for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
[math.degrees(i) for i in tri.angles()]
# [45.0, 90.0, 45.0]
QgsTriangle().angles()
# []

QDomElement QgsTriangle::asGml3(QDomDocument& doc, int precision = 17, const QString& ns = "gml", QgsAbstractGeometry::AxisOrder axisOrder = QgsAbstractGeometry::AxisOrder::XY) const override

Returns a GML3 representation of the geometry.

Parameters
doc DOM document
precision number of decimal places for coordinates
ns XML namespace
axisOrder Axis order for generated GML

QVector<QgsLineString> QgsTriangle::bisectors(double lengthTolerance = 0.0001) const

The segment (defined by a QgsLineString) returned bisect the angle of a vertex to the opposite side.

Parameters
lengthTolerance The tolerance to use.
Returns

Three angle bisector from this triangle. An empty list is returned for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
[bis.asWkt() for bis in tri.bisectors()]
# ['LineString (0 0, 2.07106781186547462 5)', 'LineString (0 5, 2.5 2.5)', 'LineString (5 5, 0 2.92893218813452538)']
QgsTriangle().bisectors()
# []

QgsCurve* QgsTriangle::boundary() const override

Returns the closure of the combinatorial boundary of the geometry (ie the topological boundary of the geometry).

Returns boundary for geometry. May be null for some geometry types.

For instance, a polygon geometry will have a boundary consisting of the linestrings for each ring in the polygon.

const QgsTriangle* QgsTriangle::cast(const QgsAbstractGeometry* geom) const

Cast the geom to a QgsTriangle.

Should be used by qgsgeometry_cast<QgsTriangle *>( geometry ).

QgsPoint QgsTriangle::circumscribedCenter() const

Center of the circumscribed circle of the triangle.

Returns

The center of the circumscribed circle of the triangle. An empty point is returned for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
tri.circumscribedCenter().asWkt()
# 'Point (2.5 2.5)'
QgsTriangle().circumscribedCenter().asWkt()
# 'Point (0 0)'

QgsCircle QgsTriangle::circumscribedCircle() const

Circumscribed circle of the triangle.

Returns

The circumbscribed of the triangle with a QgsCircle. An empty circle is returned for empty triangle. Example:

tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
tri.circumscribedCircle()
# QgsCircle(Point (2.5 2.5), 3.5355339059327378, 0)
QgsTriangle().circumscribedCircle()
# QgsCircle()

double QgsTriangle::circumscribedRadius() const

Radius of the circumscribed circle of the triangle.

Returns

The radius of the circumscribed circle of the triangle. 0.0 is returned for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
tri.circumscribedRadius()
# 3.5355339059327378
QgsTriangle().circumscribedRadius()
# 0.0

QgsTriangle* QgsTriangle::createEmptyWithSameType() const override

Creates a new geometry with the same class and same WKB type as the original and transfers ownership.

To create it, the geometry is default constructed and then the WKB is changed.

bool QgsTriangle::fromWkb(QgsConstWkbPtr& wkb) override

Sets the geometry from a WKB string.

After successful read the wkb argument will be at the position where the reading has stopped.

bool QgsTriangle::fromWkt(const QString& wkt) override

Sets the geometry from a WKT string.

QString QgsTriangle::geometryType() const override

Returns a unique string representing the geometry type.

QgsPoint QgsTriangle::inscribedCenter() const

Center of the inscribed circle of the triangle.

Returns

The center of the inscribed circle of the triangle. An empty point is returned for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
tri.inscribedCenter().asWkt()
# 'Point (1.46446609406726225 3.53553390593273775)'
QgsTriangle().inscribedCenter().asWkt()
# 'Point (0 0)'

Z dimension is supported and is retrieved from the first 3D point amongst vertices.

QgsCircle QgsTriangle::inscribedCircle() const

Inscribed circle of the triangle.

Returns

The inscribed of the triangle with a QgsCircle. An empty circle is returned for empty triangle. Example:

tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
tri.inscribedCircle()
# QgsCircle(Point (1.46446609406726225 3.53553390593273775), 1.4644660940672622, 0)
QgsTriangle().inscribedCircle()
# QgsCircle()

double QgsTriangle::inscribedRadius() const

Radius of the inscribed circle of the triangle.

Returns

The radius of the inscribed circle of the triangle. 0.0 is returned for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
tri.inscribedRadius()
# 1.4644660940672622
QgsTriangle().inscribedRadius()
# 0.0

bool QgsTriangle::isDegenerate()

Convenient method checking if the geometry is degenerate (have duplicate or colinear point(s)).

Returns

True if the triangle is degenerate or empty, otherwise false. Example:

tri = QgsTriangle()
tri.isDegenerate()
# True
tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
tri.isDegenerate()
# False
tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 5, 5 ), QgsPoint( 10, 10 ) )
tri.isDegenerate()
# True
tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 0 ), QgsPoint( 5, 5 ) )
tri.isDegenerate()
# True

bool QgsTriangle::isEquilateral(double lengthTolerance = 0.0001) const

Is the triangle equilateral (three sides with the same length)?

Parameters
lengthTolerance The tolerance to use
Returns

True or False. Always false for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 10, 10 ), QgsPoint( 16, 10 ), QgsPoint( 13, 15.1962 ) )
tri.lengths()
# [6.0, 6.0000412031918575, 6.0000412031918575]
tri.isEquilateral()
# True
# All lengths are close to 6.0
QgsTriangle().isEquilateral()
# False

bool QgsTriangle::isIsocele(double lengthTolerance = 0.0001) const

Is the triangle isocele (two sides with the same length)?

Parameters
lengthTolerance The tolerance to use
Returns

True or False. Always false for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
tri.lengths()
# [5.0, 5.0, 7.0710678118654755]
tri.isIsocele()
# True
# length of [AB] == length of [BC]
QgsTriangle().isIsocele()
# False

bool QgsTriangle::isRight(double angleTolerance = 0.0001) const

Is the triangle right-angled?

Parameters
angleTolerance The tolerance to use
Returns

True or False. Always false for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
[math.degrees(i) for i in tri.angles()]
# [45.0, 90.0, 45.0]
tri.isRight()
# True
# angle of ABC == 90
QgsTriangle().isRight()
# False

bool QgsTriangle::isScalene(double lengthTolerance = 0.0001) const

Is the triangle scalene (all sides have different lengths)?

Parameters
lengthTolerance The tolerance to use
Returns

True or False. Always false for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 7.2825, 4.2368 ), QgsPoint( 13.0058, 3.3218 ), QgsPoint( 9.2145, 6.5242 ) )
tri.lengths()
# [5.795980321740233, 4.962793714229921, 2.994131386562721]
tri.isScalene()
# True
# All lengths are different
QgsTriangle().isScalene()
# False

QVector<double> QgsTriangle::lengths() const

Returns the three lengths of the triangle.

Returns

Lengths of triangle ABC where [AB] is at 0, [BC] is at 1, [CA] is at 2. An empty list is returned for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
tri.lengths()
# [5.0, 5.0, 7.0710678118654755]
QgsTriangle().lengths()
# []

QgsTriangle QgsTriangle::medial() const

Medial (or midpoint) triangle of a triangle ABC is the triangle with vertices at the midpoints of the triangle's sides.

Returns

The medial from this triangle. An empty triangle is returned for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
tri.medial().asWkt()
# 'Triangle ((0 2.5, 2.5 5, 2.5 2.5, 0 2.5))'
QgsTriangle().medial().asWkt()
# 'Triangle ( )'

QVector<QgsLineString> QgsTriangle::medians() const

A median is a segment (defined by a QgsLineString) from a vertex to the midpoint of the opposite side.

Returns

Three medians from this triangle. An empty list is returned for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
[med.asWkt() for med in tri.medians()]
# ['LineString (0 0, 2.5 5)', 'LineString (0 5, 2.5 2.5)', 'LineString (5 5, 0 2.5)']
QgsTriangle().medians()
# []

bool QgsTriangle::moveVertex(QgsVertexId position, const QgsPoint& newPos) override

Moves a vertex within the geometry.

Parameters
position vertex id for vertex to move
newPos new position of vertex
Returns true if move was successful

QgsPoint QgsTriangle::orthocenter(double lengthTolerance = 0.0001) const

An orthocenter is the point of intersection of the altitudes of a triangle.

Parameters
lengthTolerance The tolerance to use
Returns

The orthocenter of the triangle. An empty point is returned for empty triangle.

  • Example:

    tri = QgsTriangle( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 5, 5 ) )
tri.orthocenter().asWkt()
# 'Point (0 5)'
QgsTriangle().orthocenter().asWkt()
# 'Point (0 0)'

void QgsTriangle::setExteriorRing(QgsCurve* ring) override

Sets the exterior ring of the polygon.

Parameters
ring new exterior ring. Ownership is transferred to the CurvePolygon.

The CurvePolygon type will be updated to match the dimensionality of the exterior ring. For instance, setting a 2D exterior ring on a 3D CurvePolygon will drop the z dimension from the CurvePolygon and all interior rings.

void QgsTriangle::setInteriorRings(const QVector<QgsCurve*>& rings) deleted

Inherited method not used.

You cannot add an interior ring into a triangle.

QgsPolygon* QgsTriangle::surfaceToPolygon() const override

Gets a polygon representation of this surface.

Ownership is transferred to the caller.

QgsCurvePolygon* QgsTriangle::toCurveType() const override

Returns the geometry converted to the more generic curve type QgsCurvePolygon.

Returns the converted geometry. Caller takes ownership

QgsPoint QgsTriangle::vertexAt(int atVertex) const

Returns coordinates of a vertex.

Parameters
atVertex index of the vertex
Returns Coordinates of the vertex or QgsPoint(0,0) on error (atVertex < 0 or > 3).