GEOS
3.9.1dev
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#include <LineSegment.h>
Classes | |
struct | HashCode |
Public Member Functions | |
LineSegment () | |
Segment end. More... | |
LineSegment (const Coordinate &c0, const Coordinate &c1) | |
Constructs a LineSegment with the given start and end Coordinates. More... | |
LineSegment (double x0, double y0, double x1, double y1) | |
void | setCoordinates (const Coordinate &c0, const Coordinate &c1) |
const Coordinate & | operator[] (std::size_t i) const |
Coordinate & | operator[] (std::size_t i) |
void | setCoordinates (const LineSegment &ls) |
double | getLength () const |
Computes the length of the line segment. More... | |
bool | isHorizontal () const |
bool | isVertical () const |
int | orientationIndex (const LineSegment &seg) const |
int | orientationIndex (const LineSegment *seg) const |
int | orientationIndex (const Coordinate &p) const |
Determines the orientation index of a Coordinate relative to this segment. More... | |
void | reverse () |
Reverses the direction of the line segment. More... | |
void | normalize () |
Puts the line segment into a normalized form. More... | |
double | angle () const |
void | midPoint (Coordinate &ret) const |
Computes the midpoint of the segment. More... | |
double | distance (const LineSegment &ls) const |
Computes the distance between this line segment and another one. More... | |
double | distance (const Coordinate &p) const |
Computes the distance between this line segment and a point. More... | |
double | distancePerpendicular (const Coordinate &p) const |
Computes the perpendicular distance between the (infinite) line defined by this line segment and a point. More... | |
void | pointAlong (double segmentLengthFraction, Coordinate &ret) const |
Computes the Coordinate that lies a given fraction along the line defined by this segment. More... | |
void | pointAlongOffset (double segmentLengthFraction, double offsetDistance, Coordinate &ret) const |
Computes the Coordinate that lies a given fraction along the line defined by this segment and offset from the segment by a given distance. More... | |
double | projectionFactor (const Coordinate &p) const |
Compute the projection factor for the projection of the point p onto this LineSegment. More... | |
double | segmentFraction (const Coordinate &inputPt) const |
Computes the fraction of distance (in [0.0, 1.0] ) that the projection of a point occurs along this line segment. More... | |
void | project (const Coordinate &p, Coordinate &ret) const |
Compute the projection of a point onto the line determined by this line segment. More... | |
bool | project (const LineSegment &seg, LineSegment &ret) const |
Project a line segment onto this line segment and return the resulting line segment. More... | |
void | closestPoint (const Coordinate &p, Coordinate &ret) const |
Computes the closest point on this line segment to another point. More... | |
int | compareTo (const LineSegment &other) const |
Compares this object with the specified object for order. More... | |
bool | equalsTopo (const LineSegment &other) const |
Returns true if other is topologically equal to this LineSegment (e.g. irrespective of orientation). More... | |
std::array< Coordinate, 2 > | closestPoints (const LineSegment &line) |
std::array< Coordinate, 2 > | closestPoints (const LineSegment *line) |
Coordinate | intersection (const LineSegment &line) const |
Coordinate | lineIntersection (const LineSegment &line) const |
Computes the intersection point of the lines defined by two segments, if there is one. More... | |
std::unique_ptr< LineString > | toGeometry (const GeometryFactory &gf) const |
Public Attributes | |
Coordinate | p0 |
Coordinate | p1 |
Segment start. More... | |
Friends | |
std::ostream & | operator<< (std::ostream &o, const LineSegment &l) |
Represents a line segment defined by two Coordinate. 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.
TODO: have this class keep pointers rather then real Coordinates ?
Definition at line 59 of file LineSegment.h.
geos::geom::LineSegment::LineSegment | ( | ) |
Segment end.
geos::geom::LineSegment::LineSegment | ( | const Coordinate & | c0, |
const Coordinate & | c1 | ||
) |
Constructs a LineSegment with the given start and end Coordinates.
geos::geom::LineSegment::LineSegment | ( | double | x0, |
double | y0, | ||
double | x1, | ||
double | y1 | ||
) |
double geos::geom::LineSegment::angle | ( | ) | const |
void geos::geom::LineSegment::closestPoint | ( | const Coordinate & | p, |
Coordinate & | ret | ||
) | const |
Computes the closest point on this line segment to another point.
p | the point to find the closest point to |
ret | the Coordinate to which the closest point on the line segment to the point p will be written |
std::array<Coordinate, 2> geos::geom::LineSegment::closestPoints | ( | const LineSegment & | line | ) |
Computes the closest points on two line segments.
line | the line segment to find the closest points to |
std::array<Coordinate, 2> geos::geom::LineSegment::closestPoints | ( | const LineSegment * | line | ) |
int geos::geom::LineSegment::compareTo | ( | const LineSegment & | other | ) | const |
Compares this object with the specified object for order.
Uses the standard lexicographic ordering for the points in the LineSegment.
other | the LineSegment with which this LineSegment is being compared |
double geos::geom::LineSegment::distance | ( | const LineSegment & | ls | ) | const |
Computes the distance between this line segment and another one.
double geos::geom::LineSegment::distance | ( | const Coordinate & | p | ) | const |
Computes the distance between this line segment and a point.
double geos::geom::LineSegment::distancePerpendicular | ( | const Coordinate & | p | ) | const |
Computes the perpendicular distance between the (infinite) line defined by this line segment and a point.
bool geos::geom::LineSegment::equalsTopo | ( | const LineSegment & | other | ) | const |
Returns true
if other
is topologically equal to this LineSegment (e.g. irrespective of orientation).
other | a LineSegment with which to do the comparison. |
double geos::geom::LineSegment::getLength | ( | ) | const |
Computes the length of the line segment.
Coordinate geos::geom::LineSegment::intersection | ( | const LineSegment & | line | ) | const |
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 LineIntersector class should be used.
line |
bool geos::geom::LineSegment::isHorizontal | ( | ) | const |
Tests whether the segment is horizontal.
true
if the segment is horizontal bool geos::geom::LineSegment::isVertical | ( | ) | const |
Tests whether the segment is vertical.
true
if the segment is vertical Coordinate geos::geom::LineSegment::lineIntersection | ( | const LineSegment & | line | ) | const |
Computes the intersection point of the lines defined by two 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 algorithms::LineIntersector class should be used.
line | a line segment defining a straight line |
void geos::geom::LineSegment::midPoint | ( | Coordinate & | ret | ) | const |
Computes the midpoint of the segment.
ret | will be set to the midpoint of the segment |
void geos::geom::LineSegment::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.
const Coordinate& geos::geom::LineSegment::operator[] | ( | std::size_t | i | ) | const |
Coordinate& geos::geom::LineSegment::operator[] | ( | std::size_t | i | ) |
int geos::geom::LineSegment::orientationIndex | ( | const LineSegment & | seg | ) | const |
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,
seg | the LineSegment to compare |
int geos::geom::LineSegment::orientationIndex | ( | const LineSegment * | seg | ) | const |
int geos::geom::LineSegment::orientationIndex | ( | const Coordinate & | p | ) | const |
Determines the orientation index of a Coordinate relative to this segment.
The orientation index is as defined in Orientation::index.
p | the Coordinate to compare |
p
is to the left of this segment p
is to the right of this segment p
is collinear with this segmentvoid geos::geom::LineSegment::pointAlong | ( | double | segmentLengthFraction, |
Coordinate & | ret | ||
) | const |
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.
segmentLengthFraction | the fraction of the segment length along the line |
ret | will be set to the point at that distance |
void geos::geom::LineSegment::pointAlongOffset | ( | double | segmentLengthFraction, |
double | offsetDistance, | ||
Coordinate & | ret | ||
) | const |
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.
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) |
ret | will be set to the point at that distance and offset |
IllegalStateException | if the segment has zero length |
void geos::geom::LineSegment::project | ( | const Coordinate & | p, |
Coordinate & | ret | ||
) | const |
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].
bool geos::geom::LineSegment::project | ( | const LineSegment & | seg, |
LineSegment & | ret | ||
) | const |
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.
seg | the line segment to project |
ret | the projected line segment |
double geos::geom::LineSegment::projectionFactor | ( | const Coordinate & | p | ) | const |
Compute 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 returned will be in the range (-inf, +inf)
p | the point to compute the factor for |
void geos::geom::LineSegment::reverse | ( | ) |
Reverses the direction of the line segment.
double geos::geom::LineSegment::segmentFraction | ( | const Coordinate & | inputPt | ) | const |
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 clamped to the range [0.0, 1.0]
.
inputPt | the point |
void geos::geom::LineSegment::setCoordinates | ( | const Coordinate & | c0, |
const Coordinate & | c1 | ||
) |
void geos::geom::LineSegment::setCoordinates | ( | const LineSegment & | ls | ) |
std::unique_ptr<LineString> geos::geom::LineSegment::toGeometry | ( | const GeometryFactory & | gf | ) | const |
Creates a LineString with the same coordinates as this segment
gf | the geometery factory to use |
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friend |
Coordinate geos::geom::LineSegment::p0 |
Definition at line 64 of file LineSegment.h.
Referenced by geos::geom::LineSegment::HashCode::operator()().
Coordinate geos::geom::LineSegment::p1 |
Segment start.
Definition at line 66 of file LineSegment.h.
Referenced by geos::geom::LineSegment::HashCode::operator()().