Class: QgsGeometryUtils¶

class qgis.core.QgsGeometryUtils

Bases: sip.wrapper

Contains various geometry utility functions.

Methods

angleBetweenThreePoints(x1: float, y1: float, x2: float, y2: float, x3: float, y3: float) → float

Calculates the angle between the lines AB and BC, where AB and BC described by points a, b and b, c.

Parameters
• x1 (float) – x-coordinate of point a

• y1 (float) – y-coordinate of point a

• x2 (float) – x-coordinate of point b

• y2 (float) – y-coordinate of point b

• x3 (float) – x-coordinate of point c

• y3 (float) – y-coordinate of point c

Return type

float

Returns

angle between lines in radians. Returned value is undefined if two or more points are equal.

angleOnCircle(angle: float, angle1: float, angle2: float, angle3: float) → bool

Returns true if an angle is between angle1 and angle3 on a circle described by angle1, angle2 and angle3.

Parameters
• angle (float) –

• angle1 (float) –

• angle2 (float) –

• angle3 (float) –

Return type

bool

averageAngle(x1: float, y1: float, x2: float, y2: float, x3: float, y3: float) → float

Calculates the average angle (in radians) between the two linear segments from (x1, y1) to (x2, y2) and (x2, y2) to (x3, y3).

averageAngle(a1: float, a2: float) -> float Averages two angles, correctly handling negative angles and ensuring the result is between 0 and 2 pi.

Parameters
• a1 – first angle (in radians)

• a2 – second angle (in radians)

• x1 (float) –

• y1 (float) –

• x2 (float) –

• y2 (float) –

• x3 (float) –

• y3 (float) –

Return type

float

Returns

ccwAngle(dy: float, dx: float) → float

Returns the counter clockwise angle between a line with components dx, dy and the line with dx > 0 and dy = 0

Parameters
• dy (float) –

• dx (float) –

Return type

float

circleAngleBetween(angle: float, angle1: float, angle2: float, clockwise: bool) → bool

Returns true if, in a circle, angle is between angle1 and angle2

Parameters
• angle (float) –

• angle1 (float) –

• angle2 (float) –

• clockwise (bool) –

Return type

bool

circleCenterRadius(pt1: QgsPoint, pt2: QgsPoint, pt3: QgsPoint) → Tuple[float, float, float]

Returns radius and center of the circle through pt1, pt2, pt3

Parameters
Return type

Tuple[float, float, float]

circleCircleIntersections(center1: QgsPointXY, radius1: float, center2: QgsPointXY, radius2: float) → Tuple[int, QgsPointXY, QgsPointXY]

If found, the intersection points will be stored in intersection1 and intersection2.

Return type

Tuple[int, QgsPointXY, QgsPointXY]

Returns

number of intersection points found.

New in version 3.2.

Parameters
circleCircleOuterTangents(center1: QgsPointXY, radius1: float, center2: QgsPointXY, radius2: float) → Tuple[int, QgsPointXY, QgsPointXY, QgsPointXY, QgsPointXY]

Calculates the outer tangent points for two circles, centered at center1 and center2 and with radii of radius1 and radius2 respectively.

The outer tangent points correspond to the points at which the two lines which are drawn so that they are tangential to both circles touch the circles.

The first tangent line is described by the points stored in line1P1 and line1P2, and the second line is described by the points stored in line2P1 and line2P2.

Returns the number of tangents (either 0 or 2).

New in version 3.2.

Parameters
Return type

Tuple[int, QgsPointXY, QgsPointXY, QgsPointXY, QgsPointXY]

circleClockwise(angle1: float, angle2: float, angle3: float) → bool

Returns true if the circle defined by three angles is ordered clockwise.

The angles are defined counter-clockwise from the origin, i.e. using Euclidean angles as opposed to geographic “North up” angles.

Parameters
• angle1 (float) –

• angle2 (float) –

• angle3 (float) –

Return type

bool

circleLength(x1: float, y1: float, x2: float, y2: float, x3: float, y3: float) → float

Length of a circular string segment defined by pt1, pt2, pt3

Parameters
• x1 (float) –

• y1 (float) –

• x2 (float) –

• y2 (float) –

• x3 (float) –

• y3 (float) –

Return type

float

circleTangentDirection(tangentPoint: QgsPoint, cp1: QgsPoint, cp2: QgsPoint, cp3: QgsPoint) → float

Calculates the direction angle of a circle tangent (clockwise from north in radians)

Parameters
Return type

float

closestPoint(geometry: QgsAbstractGeometry, point: QgsPoint) → QgsPoint

Returns the nearest point on a segment of a geometry for the specified point. The z and m values will be linearly interpolated between the two neighbouring vertices.

Parameters
Return type

QgsPoint

closestVertex(geom: QgsAbstractGeometry, pt: QgsPoint) → Tuple[QgsPoint, QgsVertexId]

Returns the closest vertex to a geometry for a specified point. On error null point will be returned and “id” argument will be invalid.

Parameters
Return type

Tuple[QgsPoint, QgsVertexId]

coefficients(pt1: QgsPoint, pt2: QgsPoint) → Tuple[float, float, float]

Returns the coefficients (a, b, c for equation “ax + by + c = 0”) of a line defined by points pt1 and pt2.

Parameters
• pt1 (QgsPoint) – first point.

• pt2 (QgsPoint) – second point.

• a – Output parameter, a coefficient of the equation.

• b – Output parameter, b coefficient of the equation.

• c – Output parameter, c coefficient of the equation.

New in version 3.0.

Return type

Tuple[float, float, float]

distanceToVertex(geom: QgsAbstractGeometry, id: QgsVertexId) → float

Returns the distance along a geometry from its first vertex to the specified vertex.

Parameters
Return type

float

Returns

distance to vertex (following geometry)

New in version 2.16.

extractLineStrings(geom: QgsAbstractGeometry) → object

Returns list of linestrings extracted from the passed geometry. The returned objects have to be deleted by the caller.

Parameters

geom (QgsAbstractGeometry) –

Return type

object

gradient(pt1: QgsPoint, pt2: QgsPoint) → float

Returns the gradient of a line defined by points pt1 and pt2.

Parameters
Return type

float

Returns

The gradient of this linear entity, or infinity if vertical

New in version 3.0.

interpolateArcValue(angle: float, a1: float, a2: float, a3: float, zm1: float, zm2: float, zm3: float) → float

Interpolate a value at given angle on circular arc given values (zm1, zm2, zm3) at three different angles (a1, a2, a3).

New in version 3.0.

Parameters
• angle (float) –

• a1 (float) –

• a2 (float) –

• a3 (float) –

• zm1 (float) –

• zm2 (float) –

• zm3 (float) –

Return type

float

interpolatePointOnArc(pt1: QgsPoint, pt2: QgsPoint, pt3: QgsPoint, distance: float) → QgsPoint

Interpolates a point on an arc defined by three points, pt1, pt2 and pt3. The arc will be interpolated by the specified distance from pt1.

Any z or m values present in the points will also be linearly interpolated in the output.

New in version 3.4.

Parameters
Return type

QgsPoint

interpolatePointOnLine(x1: float, y1: float, x2: float, y2: float, fraction: float) → QgsPointXY

Interpolates the position of a point a fraction of the way along the line from (x1, y1) to (x2, y2).

Usually the fraction should be between 0 and 1, where 0 represents the point at the start of the line (x1, y1) and 1 represents the end of the line (x2, y2). However, it is possible to use a fraction < 0 or > 1, in which case the returned point is extrapolated from the supplied line.

New in version 3.0.2.

interpolatePointOnLine(p1: QgsPoint, p2: QgsPoint, fraction: float) -> QgsPoint Interpolates the position of a point a fraction of the way along the line from p1 to p2.

Usually the fraction should be between 0 and 1, where 0 represents the point at the start of the line (p1) and 1 represents the end of the line (p2). However, it is possible to use a fraction < 0 or > 1, in which case the returned point is extrapolated from the supplied line.

Any Z or M values present in the input points will also be interpolated and present in the returned point.

New in version 3.0.2.

Parameters
• x1 (float) –

• y1 (float) –

• x2 (float) –

• y2 (float) –

• fraction (float) –

Return type

QgsPointXY

interpolatePointOnLineByValue(x1: float, y1: float, v1: float, x2: float, y2: float, v2: float, value: float) → QgsPointXY

Interpolates the position of a point along the line from (x1, y1) to (x2, y2).

The position is interpolated using a supplied target value and the value at the start of the line (v1) and end of the line (v2). The returned point will be linearly interpolated to match position corresponding to the target value.

New in version 3.0.2.

Parameters
• x1 (float) –

• y1 (float) –

• v1 (float) –

• x2 (float) –

• y2 (float) –

• v2 (float) –

• value (float) –

Return type

QgsPointXY

leftOfLine(x: float, y: float, x1: float, y1: float, x2: float, y2: float) → int

Returns a value < 0 if the point (x, y) is left of the line from (x1, y1) -> ( x2, y2). A positive return value indicates the point is to the right of the line.

If the return value is 0, then the test was unsuccessful (e.g. due to testing a point exactly on the line, or exactly in line with the segment) and the result is undefined.

Parameters
• x (float) –

• y (float) –

• x1 (float) –

• y1 (float) –

• x2 (float) –

• y2 (float) –

Return type

int

lineAngle(x1: float, y1: float, x2: float, y2: float) → float

Calculates the direction of line joining two points in radians, clockwise from the north direction.

Parameters
• x1 (float) – x-coordinate of line start

• y1 (float) – y-coordinate of line start

• x2 (float) – x-coordinate of line end

• y2 (float) – y-coordinate of line end

Return type

float

Returns

angle in radians. Returned value is undefined if start and end point are the same.

lineCircleIntersection(center: QgsPointXY, radius: float, linePoint1: QgsPointXY, linePoint2: QgsPointXY, intersection: QgsPointXY) → Tuple[bool, QgsPointXY]

Compute the intersection of a line and a circle. If the intersection has two solutions (points), the closest point to the initial intersection point is returned.

Parameters
• center (QgsPointXY) – the center of the circle

• linePoint1 (QgsPointXY) – a first point on the line

• linePoint2 (QgsPointXY) – a second point on the line

• intersection (QgsPointXY) – the initial point and the returned intersection point

Return type

Tuple[bool, QgsPointXY]

Returns

true if an intersection has been found

lineIntersection(p1: QgsPoint, v1: QgsVector, p2: QgsPoint, v2: QgsVector) → Tuple[bool, QgsPoint]

Computes the intersection between two lines. Z dimension is supported and is retrieved from the first 3D point amongst p1 and p2.

Parameters
• p1 (QgsPoint) – Point on the first line

• v1 (QgsVector) – Direction vector of the first line

• p2 (QgsPoint) – Point on the second line

• v2 (QgsVector) – Direction vector of the second line

• intersection – Output parameter, the intersection point

Return type

Tuple[bool, QgsPoint]

Returns

Whether the lines intersect

linePerpendicularAngle(x1: float, y1: float, x2: float, y2: float) → float

Calculates the perpendicular angle to a line joining two points. Returned angle is in radians, clockwise from the north direction.

Parameters
• x1 (float) – x-coordinate of line start

• y1 (float) – y-coordinate of line start

• x2 (float) – x-coordinate of line end

• y2 (float) – y-coordinate of line end

Return type

float

Returns

angle in radians. Returned value is undefined if start and end point are the same.

linesIntersection3D(La1: QgsVector3D, La2: QgsVector3D, Lb1: QgsVector3D, Lb2: QgsVector3D) → Tuple[bool, QgsVector3D]

An algorithm to calculate an (approximate) intersection of two lines in 3D.

Parameters
• La1 (QgsVector3D) – is the first point on the first line,

• La2 (QgsVector3D) – is the second point on the first line,

• Lb1 (QgsVector3D) – is the first point on the second line,

• Lb2 (QgsVector3D) – is the second point on the second line,

• intersection – is the result intersection, of it can be found.

Return type

Tuple[bool, QgsVector3D]

Returns

true if the intersection can be found, false - otherwise. example:

QgsGeometryUtils.linesIntersection3D(QgsVector3D(0,0,0), QgsVector3D(5,0,0), QgsVector3D(2,1,0), QgsVector3D(2,3,0))
# (True, PyQt5.QtGui.QgsVector3D(2.0, 0.0, 0.0))
QgsGeometryUtils.linesIntersection3D(QgsVector3D(0,0,0), QgsVector3D(5,0,0), QgsVector3D(2,1,0), QgsVector3D(2,0,0))
# (True, PyQt5.QtGui.QgsVector3D(2.0, 0.0, 0.0))
QgsGeometryUtils.linesIntersection3D(QgsVector3D(0,0,0), QgsVector3D(5,0,0), QgsVector3D(0,1,0), QgsVector3D(0,3,0))
# (True, PyQt5.QtGui.QgsVector3D(0.0, 0.0, 0.0))
QgsGeometryUtils.linesIntersection3D(QgsVector3D(0,0,0), QgsVector3D(5,0,0), QgsVector3D(0,1,0), QgsVector3D(0,0,0))
# (True, PyQt5.QtGui.QgsVector3D(0.0, 0.0, 0.0))
QgsGeometryUtils.linesIntersection3D(QgsVector3D(0,0,0), QgsVector3D(5,0,0), QgsVector3D(5,1,0), QgsVector3D(5,3,0))
# (False, PyQt5.QtGui.QgsVector3D(0.0, 0.0, 0.0))
QgsGeometryUtils.linesIntersection3D(QgsVector3D(0,0,0), QgsVector3D(5,0,0), QgsVector3D(5,1,0), QgsVector3D(5,0,0))
# (False, PyQt5.QtGui.QgsVector3D(0.0, 0.0, 0.0))
QgsGeometryUtils.linesIntersection3D(QgsVector3D(1,1,0), QgsVector3D(2,2,0), QgsVector3D(3,1,0), QgsVector3D(3,2,0))
# (True, PyQt5.QtGui.QgsVector3D(3.0, 3.0, 0.0))
QgsGeometryUtils.linesIntersection3D(QgsVector3D(1,1,0), QgsVector3D(2,2,0), QgsVector3D(3,2,0), QgsVector3D(3,1,0))
# (True, PyQt5.QtGui.QgsVector3D(3.0, 3.0, 0.0))
QgsGeometryUtils.linesIntersection3D(QgsVector3D(5,5,5), QgsVector3D(0,0,0), QgsVector3D(0,5,5), QgsVector3D(5,0,0))
# (True, PyQt5.QtGui.QgsVector3D(2.5, 2.5, 2.5))
QgsGeometryUtils.linesIntersection3D(QgsVector3D(2.5,2.5,2.5), QgsVector3D(0,5,0), QgsVector3D(2.5,2.5,2.5), QgsVector3D(5,0,0))
# (True, PyQt5.QtGui.QgsVector3D(2.5, 2.5, 2.5))
QgsGeometryUtils.linesIntersection3D(QgsVector3D(2.5,2.5,2.5), QgsVector3D(5,0,0), QgsVector3D(0,5,5), QgsVector3D(5,5,5))
# (True, PyQt5.QtGui.QgsVector3D(0.0, 5.0, 5.0))
midpoint(pt1: QgsPoint, pt2: QgsPoint) → QgsPoint

Returns a middle point between points pt1 and pt2. Z value is computed if one of this point have Z. M value is computed if one of this point have M.

Parameters
Return type

QgsPoint

Returns

New point at middle between points pt1 and pt2. * Example:

p = QgsPoint( 4, 6 ) # 2D point
pr = midpoint ( p, QgsPoint( 2, 2 ) )
# pr is a 2D point: 'Point (3 4)'
pr = midpoint ( p, QgsPoint( QgsWkbTypes.PointZ, 2, 2, 2 ) )
# pr is a 3D point: 'PointZ (3 4 1)'
pr = midpoint ( p, QgsPoint( QgsWkbTypes.PointM, 2, 2, 0, 2 ) )
# pr is a 3D point: 'PointM (3 4 1)'
pr = midpoint ( p, QgsPoint( QgsWkbTypes.PointZM, 2, 2, 2, 2 ) )
# pr is a 3D point: 'PointZM (3 4 1 1)'

New in version 3.0.

normalizedAngle(angle: float) → float

Ensures that an angle is in the range 0 <= angle < 2 pi.

Parameters

angle (float) – angle in radians

Return type

float

Returns

equivalent angle within the range [0, 2 pi)

perpendicularSegment(p: QgsPoint, s1: QgsPoint, s2: QgsPoint) → QgsLineString

Create a perpendicular line segment from p to segment [s1, s2]

Parameters
Return type

QgsLineString

Returns

A line (segment) from p to perpendicular point on segment [s1, s2]

pointOnLineWithDistance(startPoint: QgsPoint, directionPoint: QgsPoint, distance: float) → QgsPoint

Returns a point a specified distance toward a second point.

Parameters
Return type

QgsPoint

projectPointOnSegment(p: QgsPoint, s1: QgsPoint, s2: QgsPoint) → QgsPoint

Project the point on a segment

Parameters
Return type

QgsPoint

Returns

The projection of the point on the segment

segmentIntersection(p1: QgsPoint, p2: QgsPoint, q1: QgsPoint, q2: QgsPoint, tolerance: float = 1e-08, acceptImproperIntersection: bool = False) → Tuple[bool, QgsPoint, bool]

Compute the intersection between two segments

Parameters
• p1 (QgsPoint) – First segment start point

• p2 (QgsPoint) – First segment end point

• q1 (QgsPoint) – Second segment start point

• q2 (QgsPoint) – Second segment end point

• intersectionPoint – Output parameter, the intersection point

• isIntersection – Output parameter, return true if an intersection is found

• tolerance (float = 1e-08) – The tolerance to use

• acceptImproperIntersection (bool = False) – By default, this method returns true only if segments have proper intersection. If set true, returns also true if segments have improper intersection (end of one segment on other segment ; continuous segments).

Return type

Tuple[bool, QgsPoint, bool]

Returns

Whether the segments intersect * Example:

ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, 0 ), QgsPoint( 0, 1 ), QgsPoint( 1, 1 ), QgsPoint( 1, 0 ) )
ret, ret.asWkt(), ret
# Whether the segments intersect, the intersection point, is intersect
# (False, 'Point (0 0)', False)
ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 0, 5 ), QgsPoint( 1, 5 ) )
ret, ret.asWkt(), ret
# (False, 'Point (0 5)', True)
ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 0, 5 ), QgsPoint( 1, 5 ), acceptImproperIntersection=True )
ret, ret.asWkt(), ret
# (True, 'Point (0 5)', True)
ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 0, 2 ), QgsPoint( 1, 5 ) )
ret, ret.asWkt(), ret
# (False, 'Point (0 2)', True)
ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 0, 2 ), QgsPoint( 1, 5 ), acceptImproperIntersection=True )
ret, ret.asWkt(), ret
# (True, 'Point (0 2)', True)
ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, -5 ), QgsPoint( 0, 5 ), QgsPoint( 2, 0 ), QgsPoint( -1, 0 ) )
ret, ret.asWkt(), ret
# (True, 'Point (0 0)', True)
segmentMidPoint(p1: QgsPoint, p2: QgsPoint, radius: float, mousePos: QgsPoint) → Tuple[bool, QgsPoint]

Calculates midpoint on circle passing through p1 and p2, closest to the given coordinate mousePos. Z dimension is supported and is retrieved from the first 3D point amongst p1 and p2.

Parameters
Return type

Tuple[bool, QgsPoint]

segmentMidPointFromCenter(p1: QgsPoint, p2: QgsPoint, center: QgsPoint, useShortestArc: bool = True) → QgsPoint

Calculates the midpoint on the circle passing through p1 and p2, with the specified center coordinate.

If useShortestArc is true, then the midpoint returned will be that corresponding to the shorter arc from p1 to p2. If it is false, the longer arc from p1 to p2 will be used (i.e. winding the other way around the circle).

New in version 3.2.

Parameters
Return type

QgsPoint

segmentSide(pt1: QgsPoint, pt3: QgsPoint, pt2: QgsPoint) → int

For line defined by points pt1 and pt3, find out on which side of the line is point pt3. Returns -1 if pt3 on the left side, 1 if pt3 is on the right side or 0 if pt3 lies on the line.

New in version 3.0.

Parameters
Return type

int

segmentizeArc(p1: QgsPoint, p2: QgsPoint, p3: QgsPoint, tolerance: float = M_PI_2/90, toleranceType: QgsAbstractGeometry.SegmentationToleranceType = QgsAbstractGeometry.MaximumAngle, hasZ: bool = False, hasM: bool = False) → List[QgsPoint]

Convert circular arc defined by p1, p2, p3 (p1/p3 being start resp. end point, p2 lies on the arc) into a sequence of points.

New in version 3.0.

Parameters
• p1 (QgsPoint) –

• p2 (QgsPoint) –

• p3 (QgsPoint) –

• tolerance (float = M_PI_2/90) –

• toleranceType (QgsAbstractGeometry.SegmentationToleranceType = QgsAbstractGeometry.MaximumAngle) –

• hasZ (bool = False) –

• hasM (bool = False) –

Return type

List[QgsPoint]

setZValueFromPoints(points: object, point: QgsPoint) → bool

A Z dimension is added to point if one of the point in the list points is in 3D. Moreover, the Z value of point is updated with.

Parameters
• points (object) – List of points in which a 3D point is searched.

• point (QgsPoint) – The point to update with Z dimension and value.

Return type

bool

Returns

true if the point is updated, false otherwise

New in version 3.0.

skewLinesDistance(P1: QgsVector3D, P12: QgsVector3D, P2: QgsVector3D, P22: QgsVector3D) → float

An algorithm to calculate the shortest distance between two skew lines.

Parameters
• P1 (QgsVector3D) – is the first point of the first line,

• P12 (QgsVector3D) – is the second point on the first line,

• P2 (QgsVector3D) – is the first point on the second line,

• P22 (QgsVector3D) – is the second point on the second line.

Return type

float

Returns

the shortest distance

skewLinesProjection(P1: QgsVector3D, P12: QgsVector3D, P2: QgsVector3D, P22: QgsVector3D, epsilon: float = 0.0001) → Tuple[bool, QgsVector3D]

A method to project one skew line onto another.

Parameters
• P1 (QgsVector3D) – is a first point that belonds to first skew line,

• P12 (QgsVector3D) – is the second point that belongs to first skew line,

• P2 (QgsVector3D) – is the first point that belongs to second skew line,

• P22 (QgsVector3D) – is the second point that belongs to second skew line,

• X1 – is the result projection point of line P2P22 onto line P1P12,

• epsilon (float = 0.0001) – the tolerance to use.

Return type

Tuple[bool, QgsVector3D]

Returns

true if such point exists, false - otherwise.

sqrDistToLine(ptX: float, ptY: float, x1: float, y1: float, x2: float, y2: float, epsilon: float) → Tuple[float, float, float]

Returns the squared distance between a point and a line.

Parameters
• ptX (float) –

• ptY (float) –

• x1 (float) –

• y1 (float) –

• x2 (float) –

• y2 (float) –

• epsilon (float) –

Return type

Tuple[float, float, float]

sqrDistance2D(pt1: QgsPoint, pt2: QgsPoint) → float

Returns the squared 2D distance between two points.

Parameters
Return type

float

sweepAngle(centerX: float, centerY: float, x1: float, y1: float, x2: float, y2: float, x3: float, y3: float) → float

Calculates angle of a circular string part defined by pt1, pt2, pt3

Parameters
• centerX (float) –

• centerY (float) –

• x1 (float) –

• y1 (float) –

• x2 (float) –

• y2 (float) –

• x3 (float) –

• y3 (float) –

Return type

float

tangentPointAndCircle(center: QgsPointXY, radius: float, p: QgsPointXY) → Tuple[bool, QgsPointXY, QgsPointXY]

Calculates the tangent points between the circle with the specified center and radius and the point p.

If found, the tangent points will be stored in pt1 and pt2.

New in version 3.2.

Parameters
Return type

Tuple[bool, QgsPointXY, QgsPointXY]

verticesAtDistance(geometry: QgsAbstractGeometry, distance: float) → Tuple[bool, QgsVertexId, QgsVertexId]

Retrieves the vertices which are before and after the interpolated point at a specified distance along a linestring (or polygon boundary).

Parameters
• geometry (QgsAbstractGeometry) – line or polygon geometry

• distance (float) – distance to traverse along geometry

• previousVertex – will be set to previous vertex ID

• nextVertex – will be set to next vertex ID

Return type

Tuple[bool, QgsVertexId, QgsVertexId]

Returns

true if vertices were successfully retrieved

Note

if the distance coincides exactly with a vertex, then both previousVertex and nextVertex will be set to this vertex

New in version 3.0.