Class LineSegment

Represents a line segment defined by two Coordinates. Provides methods to compute various geometric properties and relationships of line segments. This class is designed to be easily mutable (to the extent of having its contained points public). This supports a common pattern of reusing a single LineSegment object as a way of computing segment properties on the segments defined by arrays or lists of Coordinates.

Inheritance

Object

LineSegment

TaggedLineSegment

Implements

IComparable<LineSegment>

Inherited Members

Object.Equals(Object, Object)

Object.GetType()

Object.MemberwiseClone()

Object.ReferenceEquals(Object, Object)

Namespace: NetTopologySuite.Geometries

Assembly: NetTopologySuite.dll

Syntax

[Serializable]
public class LineSegment : IComparable<LineSegment>

Constructors

LineSegment()

Declaration

public LineSegment()

LineSegment(Coordinate, Coordinate)

Creates an instance of this class using two coordinates

Declaration

public LineSegment(Coordinate p0, Coordinate p1)

Parameters

Type	Name	Description
Coordinate	p0	The start-point
Coordinate	p1	The end-point

LineSegment(LineSegment)

Creates an instance of this class using another instance

Declaration

public LineSegment(LineSegment ls)

Parameters

Type	Name	Description
LineSegment	ls

LineSegment(Double, Double, Double, Double)

Creates an instance of this class

Declaration

public LineSegment(double x0, double y0, double x1, double y1)

Parameters

Type	Name	Description
Double	x0
Double	y0
Double	x1
Double	y1

Properties

Angle

Declaration

public double Angle { get; }

Property Value

Type	Description
Double	The angle this segment makes with the x-axis (in radians).

IsHorizontal

Tests whether the segment is horizontal.

Declaration

public bool IsHorizontal { get; }

Property Value

Type	Description
Boolean	true if the segment is horizontal.

IsVertical

Tests whether the segment is vertical.

Declaration

public bool IsVertical { get; }

Property Value

Type	Description
Boolean	true if the segment is vertical.

Length

Computes the length of the line segment.

Declaration

public double Length { get; }

Property Value

Type	Description
Double	The length of the line segment.

MaxX

Gets the maximum X ordinate

Declaration

public double MaxX { get; }

Property Value

Type	Description
Double

MaxY

Gets the maximum Y ordinate

Declaration

public double MaxY { get; }

Property Value

Type	Description
Double

MidPoint

The midpoint of the segment

Declaration

public Coordinate MidPoint { get; }

Property Value

Type	Description
Coordinate

MinX

Gets the minimum X ordinate

Declaration

public double MinX { get; }

Property Value

Type	Description
Double

MinY

Gets the minimum Y ordinate

Declaration

public double MinY { get; }

Property Value

Type	Description
Double

P0

The start-point

Declaration

public Coordinate P0 { get; set; }

Property Value

Type	Description
Coordinate

P1

The end-point

Declaration

public Coordinate P1 { get; set; }

Property Value

Type	Description
Coordinate

Methods

ClosestPoint(Coordinate)

Computes the closest point on this line segment to another point.

Declaration

public Coordinate ClosestPoint(Coordinate p)

Parameters

Type	Name	Description
Coordinate	p	The point to find the closest point to.

Returns

Type	Description
Coordinate	A Coordinate which is the closest point on the line segment to the point p.

ClosestPoints(LineSegment)

Computes the closest points on a line segment.

Declaration

public Coordinate[] ClosestPoints(LineSegment line)

Parameters

Type	Name	Description
LineSegment	line

Returns

Type	Description
Coordinate[]	A pair of Coordinates which are the closest points on the line segments.

CompareTo(LineSegment)

Compares this object with the specified object for order. Uses the standard lexicographic ordering for the points in the LineSegment.

Declaration

public int CompareTo(LineSegment other)

Parameters

Type	Name	Description
LineSegment	other	The LineSegment with which this LineSegment is being compared.

Returns

Type	Description
Int32	A negative integer, zero, or a positive integer as this LineSegment is less than, equal to, or greater than the specified LineSegment.

Distance(Coordinate)

Computes the distance between this line segment and a point.

Declaration

public double Distance(Coordinate p)

Parameters

Type	Name	Description
Coordinate	p

Returns

Type	Description
Double

Distance(LineSegment)

Computes the distance between this line segment and another one.

Declaration

public double Distance(LineSegment ls)

Parameters

Type	Name	Description
LineSegment	ls

Returns

Type	Description
Double

DistancePerpendicular(Coordinate)

Computes the perpendicular distance between the (infinite) line defined by this line segment and a point.

Declaration

public double DistancePerpendicular(Coordinate p)

Parameters

Type	Name	Description
Coordinate	p

Returns

Type	Description
Double

Equals(Object)

Returns true if o has the same values for its points.

Declaration

public override bool Equals(object o)

Parameters

Type	Name	Description
Object	o	A LineSegment with which to do the comparison.

Returns

Type	Description
Boolean	true if o is a LineSegment with the same values for the x and y ordinates.

Overrides

Object.Equals(Object)

EqualsTopologically(LineSegment)

Returns true if other is topologically equal to this LineSegment (e.g. irrespective of orientation).

Declaration

public bool EqualsTopologically(LineSegment other)

Parameters

Type	Name	Description
LineSegment	other	A LineSegment with which to do the comparison.

Returns

Type	Description
Boolean	true if other is a LineSegment with the same values for the x and y ordinates.

GetCoordinate(Int32)

Declaration

public Coordinate GetCoordinate(int i)

Parameters

Type	Name	Description
Int32	i

Returns

Type	Description
Coordinate

GetHashCode()

Return HashCode.

Declaration

public override int GetHashCode()

Returns

Type	Description
Int32

Overrides

Object.GetHashCode()

Intersection(LineSegment)

Computes an intersection point between two segments, if there is one. There may be 0, 1 or many intersection points between two segments. If there are 0, null is returned. If there is 1 or more, a single one is returned (chosen at the discretion of the algorithm). If more information is required about the details of the intersection, the RobustLineIntersector class should be used.

Declaration

public Coordinate Intersection(LineSegment line)

Parameters

Type	Name	Description
LineSegment	line	A line segment

Returns

Type	Description
Coordinate	An intersection point, or null if there is none.

LineIntersection(LineSegment)

Computes the intersection point of the lines defined by two segments, if there is one.

Declaration

public Coordinate LineIntersection(LineSegment line)

Parameters

Type	Name	Description
LineSegment	line	A line segment defining a straight line

Returns

Type	Description
Coordinate	An intersection point, or null if there is none or an infinite number

Remarks

There may be 0, 1 or an infinite number of intersection points between two lines. If there is a unique intersection point, it is returned. Otherwise, null is returned. If more information is required about the details of the intersection, the RobustLineIntersector class should be used.

See Also

RobustLineIntersector

Normalize()

Puts the line segment into a normalized form. This is useful for using line segments in maps and indexes when topological equality rather than exact equality is desired.

Declaration

public void Normalize()

Offset(Double)

Computes the LineSegment that is offset from the segment by a given distance. The computed segment is offset to the left of the line if the offset distance is positive, to the right if negative.

Declaration

public LineSegment Offset(double offsetDistance)

Parameters

Type	Name	Description
Double	offsetDistance	The distance the point is offset from the segment (positive is to the left, negative is to the right)

Returns

Type	Description
LineSegment	A line segment offset by the specified distance

Exceptions

Type	Condition
ApplicationException	Thrown if the segment has zero length

OrientationIndex(Coordinate)

Determines the orientation index of a Coordinate relative to this segment. The orientation index is as defined in Index(Coordinate, Coordinate, Coordinate).

Declaration

public int OrientationIndex(Coordinate p)

Parameters

Type	Name	Description
Coordinate	p

Returns

Type	Description
Int32	1 if p is to the left of this segment -1 if p is to the right of this segment 0 if p is collinear with this segment "

OrientationIndex(LineSegment)

Determines the orientation of a LineSegment relative to this segment. The concept of orientation is specified as follows: Given two line segments A and L, A is to the left of a segment L if A lies wholly in the closed half-plane lying to the left of L A is to the right of a segment L if A lies wholly in the closed half-plane lying to the right of L otherwise, A has indeterminate orientation relative to L. This happens if A is collinear with L or if A crosses the line determined by L.

Declaration

public int OrientationIndex(LineSegment seg)

Parameters

Type	Name	Description
LineSegment	seg	The LineSegment to compare.

Returns

Type	Description
Int32	1 if seg is to the left of this segment, -1 if seg is to the right of this segment, 0 if seg is collinear to or crosses this segment.

PointAlong(Double)

Computes the Coordinate that lies a given fraction along the line defined by this segment.

Declaration

public Coordinate PointAlong(double segmentLengthFraction)

Parameters

Type	Name	Description
Double	segmentLengthFraction	the fraction of the segment length along the line

Returns

Type	Description
Coordinate	the point at that distance

Remarks

A fraction of 0.0 returns the start point of the segment; A fraction of 1.0 returns the end point of the segment. If the fraction is < 0.0 or > 1.0 the point returned will lie before the start or beyond the end of the segment.

PointAlongOffset(Double, Double)

Computes the Coordinate that lies a given

Declaration

public Coordinate PointAlongOffset(double segmentLengthFraction, double offsetDistance)

Parameters

Type	Name	Description
Double	segmentLengthFraction	the fraction of the segment length along the line
Double	offsetDistance	the distance the point is offset from the segment

Returns

Type	Description
Coordinate	the point at that distance and offset

Remarks

A fraction along the line defined by this segment and offset from the segment by a given distance. A fraction of 0.0 offsets from the start point of the segment; A fraction of 1.0 offsets from the end point of the segment. The computed point is offset to the left of the line if the offset distance is positive, to the right if negative.

Exceptions

Type	Condition
ApplicationException	if the segment has zero length

Project(Coordinate)

Compute the projection of a point onto the line determined by this line segment. Note that the projected point may lie outside the line segment. If this is the case, the projection factor will lie outside the range [0.0, 1.0].

Declaration

public Coordinate Project(Coordinate p)

Parameters

Type	Name	Description
Coordinate	p

Returns

Type	Description
Coordinate

Project(LineSegment)

Project a line segment onto this line segment and return the resulting line segment. The returned line segment will be a subset of the target line line segment. This subset may be null, if the segments are oriented in such a way that there is no projection. Note that the returned line may have zero length (i.e. the same endpoints). This can happen for instance if the lines are perpendicular to one another.

Declaration

public LineSegment Project(LineSegment seg)

Parameters

Type	Name	Description
LineSegment	seg	The line segment to project.

Returns

Type	Description
LineSegment	The projected line segment, or null if there is no overlap.

ProjectionFactor(Coordinate)

Computes the Projection Factor for the projection of the point p onto this LineSegment. The Projection Factor is the constant r by which the vector for this segment must be multiplied to equal the vector for the projection of p on the line defined by this segment.

The projection factor will lie in the range (-inf, +inf), or be NaN if the line segment has zero length.

Declaration

public double ProjectionFactor(Coordinate p)

Parameters

Type	Name	Description
Coordinate	p	The point to compute the factor for

Returns

Type	Description
Double	The projection factor for the point

Reflect(Coordinate)

Computes the reflection of a point in the line defined by this line segment.

Declaration

public Coordinate Reflect(Coordinate p)

Parameters

Type	Name	Description
Coordinate	p	The point to reflect

Returns

Type	Description
Coordinate	The reflected point

Reverse()

Reverses the direction of the line segment.

Declaration

public void Reverse()

SegmentFraction(Coordinate)

Computes the fraction of distance (in [0.0, 1.0]) that the projection of a point occurs along this line segment. If the point is beyond either ends of the line segment, the closest fractional value (0.0 or 1.0) is returned.

Declaration

public double SegmentFraction(Coordinate inputPt)

Parameters

Type	Name	Description
Coordinate	inputPt	the point

Returns

Type	Description
Double	the fraction along the line segment the projection of the point occurs

Remarks

Essentially, this is the ProjectionFactor(Coordinate) clamped to the range [0.0, 1.0].

SetCoordinates(Coordinate, Coordinate)

Declaration

public void SetCoordinates(Coordinate p0, Coordinate p1)

Parameters

Type	Name	Description
Coordinate	p0
Coordinate	p1

SetCoordinates(LineSegment)

Declaration

public void SetCoordinates(LineSegment ls)

Parameters

Type	Name	Description
LineSegment	ls

ToGeometry(GeometryFactory)

Creates a LineString with the same coordinates as this segment

Declaration

public LineString ToGeometry(GeometryFactory geomFactory)

Parameters

Type	Name	Description
GeometryFactory	geomFactory	the geometry factory to use

Returns

Type	Description
LineString	A LineString with the same geometry as this segment

ToString()

Declaration

public override string ToString()

Returns

Type	Description
String

Overrides

Object.ToString()

Operators

Equality(LineSegment, LineSegment)

Declaration

public static bool operator ==(LineSegment obj1, LineSegment obj2)

Parameters

Type	Name	Description
LineSegment	obj1
LineSegment	obj2

Returns

Type	Description
Boolean

Inequality(LineSegment, LineSegment)

Declaration

public static bool operator !=(LineSegment obj1, LineSegment obj2)

Parameters

Type	Name	Description
LineSegment	obj1
LineSegment	obj2

Returns

Type	Description
Boolean

Implements

System.IComparable<T>