Class LineSegment

java.lang.Object
org.locationtech.jts.geom.LineSegment
All Implemented Interfaces:
Serializable, Comparable
public class LineSegment extends Object implements Comparable, Serializable
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.

Version:
1.7
See Also:

  • Field Details

  • Constructor Details

    • LineSegment

      public LineSegment(Coordinate p0, Coordinate p1)

    • LineSegment

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

    • LineSegment

      public LineSegment(LineSegment ls)

    • LineSegment

      public LineSegment()

  • Method Details

    • getCoordinate

      public Coordinate getCoordinate(int i)

    • setCoordinates

      public void setCoordinates(LineSegment ls)

    • setCoordinates

      public void setCoordinates(Coordinate p0, Coordinate p1)

    • minX

      public double minX()
      Gets the minimum X ordinate.
      Returns:
      the minimum X ordinate

    • maxX

      public double maxX()
      Gets the maximum X ordinate.
      Returns:
      the maximum X ordinate

    • minY

      public double minY()
      Gets the minimum Y ordinate.
      Returns:
      the minimum Y ordinate

    • maxY

      public double maxY()
      Gets the maximum Y ordinate.
      Returns:
      the maximum Y ordinate

    • getLength

      public double getLength()
      Computes the length of the line segment.
      Returns:
      the length of the line segment

    • isHorizontal

      public boolean isHorizontal()
      Tests whether the segment is horizontal.
      Returns:
      true if the segment is horizontal

    • isVertical

      public boolean isVertical()
      Tests whether the segment is vertical.
      Returns:
      true if the segment is vertical

    • orientationIndex

      public int orientationIndex(LineSegment seg)
      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.
      Parameters:
      seg - the LineSegment to compare
      Returns:
      1 if seg is to the left of this segment

    • orientationIndex

      public int orientationIndex(Coordinate p)
      Determines the orientation index of a Coordinate relative to this segment. The orientation index is as defined in Orientation.index(Coordinate, Coordinate, Coordinate).
      Parameters:
      p - the coordinate to compare
      Returns:
      1 (LEFT) if p is to the left of this segment
      See Also:

    • reverse

      public void reverse()
      Reverses the direction of the line segment.

    • normalize

      public void 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. A segment in normalized form has the first point smaller than the second (according to the standard ordering on Coordinate).

    • angle

      public double angle()
      Computes the angle that the vector defined by this segment makes with the X-axis. The angle will be in the range [ -PI, PI ] radians.
      Returns:
      the angle this segment makes with the X-axis (in radians)

    • midPoint

      public Coordinate midPoint()
      Computes the midpoint of the segment
      Returns:
      the midpoint of the segment

    • midPoint

      public static Coordinate midPoint(Coordinate p0, Coordinate p1)
      Computes the midpoint of a segment
      Returns:
      the midpoint of the segment

    • distance

      public double distance(LineSegment ls)
      Computes the distance between this line segment and another segment.
      Returns:
      the distance to the other segment

    • distance

      public double distance(Coordinate p)
      Computes the distance between this line segment and a given point.
      Returns:
      the distance from this segment to the given point

    • distancePerpendicular

      public double distancePerpendicular(Coordinate p)
      Computes the perpendicular distance between the (infinite) line defined by this line segment and a point. If the segment has zero length this returns the distance between the segment and the point.
      Parameters:
      p - the point to compute the distance to
      Returns:
      the perpendicular distance between the line and point

    • distancePerpendicularOriented

      public double distancePerpendicularOriented(Coordinate p)
      Computes the oriented perpendicular distance between the (infinite) line defined by this line segment and a point. The oriented distance is positive if the point on the left of the line, and negative if it is on the right. If the segment has zero length this returns the distance between the segment and the point.
      Parameters:
      p - the point to compute the distance to
      Returns:
      the oriented perpendicular distance between the line and point

    • pointAlong

      public Coordinate pointAlong(double segmentLengthFraction)
      Computes the Coordinate that lies a given fraction along the line defined by this segment. 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.
      Parameters:
      segmentLengthFraction - the fraction of the segment length along the line
      Returns:
      the point at that distance

    • pointAlongOffset

      public Coordinate pointAlongOffset(double segmentLengthFraction, double offsetDistance)
      Computes the Coordinate that lies a given 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.
      Parameters:
      segmentLengthFraction - the fraction of the segment length along the line
      offsetDistance - the distance the point is offset from the segment (positive is to the left, negative is to the right)
      Returns:
      the point at that distance and offset
      Throws:
      IllegalStateException - if the segment has zero length

    • projectionFactor

      public double projectionFactor(Coordinate p)
      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..

      Parameters:
      p - the point to compute the factor for
      Returns:
      the projection factor for the point

    • segmentFraction

      public double segmentFraction(Coordinate inputPt)
      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.

      Essentially, this is the projectionFactor(Coordinate) clamped to the range [0.0, 1.0]. If the segment has zero length, 1.0 is returned.

      Parameters:
      inputPt - the point
      Returns:
      the fraction along the line segment the projection of the point occurs

    • project

      public Coordinate project(Coordinate p)
      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].

    • project

      public LineSegment project(LineSegment seg)
      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.

      Parameters:
      seg - the line segment to project
      Returns:
      the projected line segment, or null if there is no overlap

    • offset

      public LineSegment offset(double offsetDistance)
      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.
      Parameters:
      offsetDistance - the distance the point is offset from the segment (positive is to the left, negative is to the right)
      Returns:
      a line segment offset by the specified distance
      Throws:
      IllegalStateException - if the segment has zero length

    • reflect

      public Coordinate reflect(Coordinate p)
      Computes the reflection of a point in the line defined by this line segment.
      Parameters:
      p - the point to reflect
      Returns:
      the reflected point

    • closestPoint

      public Coordinate closestPoint(Coordinate p)
      Computes the closest point on this line segment to another point.
      Parameters:
      p - the point to find the closest point to
      Returns:
      a Coordinate which is the closest point on the line segment to the point p

    • closestPoints

      public Coordinate[] closestPoints(LineSegment line)
      Computes the closest points on two line segments.
      Parameters:
      line - the segment to find the closest point to
      Returns:
      a pair of Coordinates which are the closest points on the line segments

    • intersection

      public Coordinate intersection(LineSegment line)
      Computes an intersection point between two line 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, exactly one of them 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.
      Parameters:
      line - a line segment
      Returns:
      an intersection point, or null if there is none
      See Also:

    • lineIntersection

      public Coordinate lineIntersection(LineSegment line)
      Computes the intersection point of the lines of infinite extent defined by two line segments (if there is one). 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.
      Parameters:
      line - a line segment defining an straight line with infinite extent
      Returns:
      an intersection point, or null if there is no point of intersection or an infinite number of intersection points
      See Also:

    • toGeometry

      public LineString toGeometry(GeometryFactory geomFactory)
      Creates a LineString with the same coordinates as this segment
      Parameters:
      geomFactory - the geometry factory to use
      Returns:
      a LineString with the same geometry as this segment

    • equals

      public boolean equals(Object o)
      Returns true if other has the same values for its points.
      Overrides:
      equals in class Object
      Parameters:
      o - a LineSegment with which to do the comparison.
      Returns:
      true if other is a LineSegment with the same values for the x and y ordinates.

    • hashCode

      public int hashCode()
      Gets a hashcode for this object.
      Overrides:
      hashCode in class Object
      Returns:
      a hashcode for this object

    • OLDhashCode

      public int OLDhashCode()

    • compareTo

      public int compareTo(Object o)
      Compares this object with the specified object for order. Uses the standard lexicographic ordering for the points in the LineSegment.
      Specified by:
      compareTo in interface Comparable
      Parameters:
      o - the LineSegment with which this LineSegment is being compared
      Returns:
      a negative integer, zero, or a positive integer as this LineSegment is less than, equal to, or greater than the specified LineSegment

    • equalsTopo

      public boolean equalsTopo(LineSegment other)
      Returns true if other is topologically equal to this LineSegment (e.g. irrespective of orientation).
      Parameters:
      other - a LineSegment with which to do the comparison.
      Returns:
      true if other is a LineSegment with the same values for the x and y ordinates.

    • toString

      public String toString()
      Overrides:
      toString in class Object