java.lang.Object
- org.meteoinfo.jts.algorithm.LineIntersector

Direct Known Subclasses:

NonRobustLineIntersector, RobustLineIntersector
```
public abstract class LineIntersector
extends java.lang.Object
```
A LineIntersector is an algorithm that can both test whether two line segments intersect and compute the intersection point(s) if they do.
There are three possible outcomes when determining whether two line segments intersect:
- NO_INTERSECTION - the segments do not intersect
- - the segments intersect in a single point
- {@link #COLLINEAR_INTERSECTION - the segments are collinear and they intersect in a line segment
For segments which intersect in a single point, the point may be either an endpoint or in the interior of each segment. If the point lies in the interior of both segments, this is termed a proper intersection. The method {@link #isProper()} test for this situation. The intersection point(s) may be computed in a precise or non-precise manner. Computing an intersection point precisely involves rounding it via a supplied {@link PrecisionModel}.
LineIntersectors do not perform an initial envelope intersection test to determine if the segments are disjoint. This is because this class is likely to be used in a context where envelope overlap is already known to occur (or be likely).

Field Summary

Fields
Modifier and Type	Field	Description
`static int`	`COLLINEAR`
`static int`	`COLLINEAR_INTERSECTION`	Indicates that line segments intersect in a line segment
`static int`	`DO_INTERSECT`
`static int`	`DONT_INTERSECT`	These are deprecated, due to ambiguous naming
`protected Coordinate[][]`	`inputLines`
`protected int[][]`	`intLineIndex`	The indexes of the endpoints of the intersection lines, in order along the corresponding line
`protected Coordinate[]`	`intPt`
`protected boolean`	`isProper`
`static int`	`NO_INTERSECTION`	Indicates that line segments do not intersect
`protected Coordinate`	`pa`
`protected Coordinate`	`pb`
`static int`	`POINT_INTERSECTION`	Indicates that line segments intersect in a single point
`protected PrecisionModel`	`precisionModel`	If makePrecise is true, computed intersection coordinates will be made precise using Coordinate#makePrecise
`protected int`	`result`

Constructor Summary

Constructors
Constructor Description

LineIntersector()

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods
Modifier and Type	Method	Description
`static double`	`computeEdgeDistance(Coordinate p, Coordinate p0, Coordinate p1)`	Computes the "edge distance" of an intersection point p along a segment.
`protected abstract int`	`computeIntersect(Coordinate p1, Coordinate p2, Coordinate q1, Coordinate q2)`
`abstract void`	`computeIntersection(Coordinate p, Coordinate p1, Coordinate p2)`	Compute the intersection of a point p and the line p1-p2.
`void`	`computeIntersection(Coordinate p1, Coordinate p2, Coordinate p3, Coordinate p4)`	Computes the intersection of the lines p1-p2 and p3-p4.
`protected void`	`computeIntLineIndex()`
`protected void`	`computeIntLineIndex(int segmentIndex)`
`double`	`getEdgeDistance(int segmentIndex, int intIndex)`	Computes the "edge distance" of an intersection point along the specified input line segment.
`Coordinate`	`getEndpoint(int segmentIndex, int ptIndex)`	Gets an endpoint of an input segment.
`int`	`getIndexAlongSegment(int segmentIndex, int intIndex)`	Computes the index (order) of the intIndex'th intersection point in the direction of a specified input line segment
`Coordinate`	`getIntersection(int intIndex)`	Returns the intIndex'th intersection point
`Coordinate`	`getIntersectionAlongSegment(int segmentIndex, int intIndex)`	Computes the intIndex'th intersection point in the direction of a specified input line segment
`int`	`getIntersectionNum()`	Returns the number of intersection points found.
`boolean`	`hasIntersection()`	Tests whether the input geometries intersect.
`protected boolean`	`isCollinear()`
`protected boolean`	`isEndPoint()`
`boolean`	`isInteriorIntersection()`	Tests whether either intersection point is an interior point of one of the input segments.
`boolean`	`isInteriorIntersection(int inputLineIndex)`	Tests whether either intersection point is an interior point of the specified input segment.
`boolean`	`isIntersection(Coordinate pt)`	Test whether a point is a intersection point of two line segments.
`boolean`	`isProper()`	Tests whether an intersection is proper.
`static double`	`nonRobustComputeEdgeDistance(Coordinate p, Coordinate p1, Coordinate p2)`	This function is non-robust, since it may compute the square of large numbers.
`void`	`setMakePrecise(PrecisionModel precisionModel)`	Deprecated. use `setPrecisionModel` instead
`void`	`setPrecisionModel(PrecisionModel precisionModel)`	Force computed intersection to be rounded to a given precision model.
`java.lang.String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - DONT_INTERSECT
```
public static final int DONT_INTERSECT
```
    These are deprecated, due to ambiguous naming
    
    See Also:
    
    Constant Field Values
  - DO_INTERSECT
```
public static final int DO_INTERSECT
```
    See Also:
    
    Constant Field Values
  - COLLINEAR
```
public static final int COLLINEAR
```
    See Also:
    
    Constant Field Values
  - NO_INTERSECTION
```
public static final int NO_INTERSECTION
```
    Indicates that line segments do not intersect
    
    See Also:
    
    Constant Field Values
  - POINT_INTERSECTION
```
public static final int POINT_INTERSECTION
```
    Indicates that line segments intersect in a single point
    
    See Also:
    
    Constant Field Values
  - COLLINEAR_INTERSECTION
```
public static final int COLLINEAR_INTERSECTION
```
    Indicates that line segments intersect in a line segment
    
    See Also:
    
    Constant Field Values
  - result
```
protected int result
```
  - inputLines
```
protected Coordinate[][] inputLines
```
  - intPt
```
protected Coordinate[] intPt
```
  - intLineIndex
```
protected int[][] intLineIndex
```
    The indexes of the endpoints of the intersection lines, in order along the corresponding line
  - isProper
```
protected boolean isProper
```
  - pa
```
protected Coordinate pa
```
  - pb
```
protected Coordinate pb
```
  - precisionModel
```
protected PrecisionModel precisionModel
```
    If makePrecise is true, computed intersection coordinates will be made precise using Coordinate#makePrecise
- Constructor Detail
  - LineIntersector
```
public LineIntersector()
```
- Method Detail
  - computeEdgeDistance
```
public static double computeEdgeDistance(Coordinate p,
                                         Coordinate p0,
                                         Coordinate p1)
```
    Computes the "edge distance" of an intersection point p along a segment. The edge distance is a metric of the point along the edge. The metric used is a robust and easy to compute metric function. It is not equivalent to the usual Euclidean metric. It relies on the fact that either the x or the y ordinates of the points in the edge are unique, depending on whether the edge is longer in the horizontal or vertical direction.
    NOTE: This function may produce incorrect distances for inputs where p is not precisely on p1-p2 (E.g. p = (139,9) p1 = (139,10), p2 = (280,1) produces distanct 0.0, which is incorrect.
    My hypothesis is that the function is safe to use for points which are the result of rounding points which lie on the line, but not safe to use for truncated points.
  - nonRobustComputeEdgeDistance
```
public static double nonRobustComputeEdgeDistance(Coordinate p,
                                                  Coordinate p1,
                                                  Coordinate p2)
```
    This function is non-robust, since it may compute the square of large numbers. Currently not sure how to improve this.
  - setMakePrecise
```
public void setMakePrecise(PrecisionModel precisionModel)
```
    Deprecated. use setPrecisionModel instead
    
    Force computed intersection to be rounded to a given precision model
    
    Parameters:
    
    precisionModel -
  - setPrecisionModel
```
public void setPrecisionModel(PrecisionModel precisionModel)
```
    Force computed intersection to be rounded to a given precision model. No getter is provided, because the precision model is not required to be specified.
    
    Parameters:
    
    precisionModel -
  - getEndpoint
```
public Coordinate getEndpoint(int segmentIndex,
                              int ptIndex)
```
    Gets an endpoint of an input segment.
    
    Parameters:
    
    segmentIndex - the index of the input segment (0 or 1)
    
    ptIndex - the index of the endpoint (0 or 1)
    
    Returns:
    
    the specified endpoint
  - computeIntersection
```
public abstract void computeIntersection(Coordinate p,
                                         Coordinate p1,
                                         Coordinate p2)
```
    Compute the intersection of a point p and the line p1-p2. This function computes the boolean value of the hasIntersection test. The actual value of the intersection (if there is one) is equal to the value of p.
  - isCollinear
```
protected boolean isCollinear()
```
  - computeIntersection
```
public void computeIntersection(Coordinate p1,
                                Coordinate p2,
                                Coordinate p3,
                                Coordinate p4)
```
    Computes the intersection of the lines p1-p2 and p3-p4. This function computes both the boolean value of the hasIntersection test and the (approximate) value of the intersection point itself (if there is one).
  - computeIntersect
```
protected abstract int computeIntersect(Coordinate p1,
                                        Coordinate p2,
                                        Coordinate q1,
                                        Coordinate q2)
```
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - isEndPoint
```
protected boolean isEndPoint()
```
  - hasIntersection
```
public boolean hasIntersection()
```
    Tests whether the input geometries intersect.
    
    Returns:
    
    true if the input geometries intersect
  - getIntersectionNum
```
public int getIntersectionNum()
```
    Returns the number of intersection points found. This will be either 0, 1 or 2.
    
    Returns:
    
    the number of intersection points found (0, 1, or 2)
  - getIntersection
```
public Coordinate getIntersection(int intIndex)
```
    Returns the intIndex'th intersection point
    
    Parameters:
    
    intIndex - is 0 or 1
    
    Returns:
    
    the intIndex'th intersection point
  - computeIntLineIndex
```
protected void computeIntLineIndex()
```
  - isIntersection
```
public boolean isIntersection(Coordinate pt)
```
    Test whether a point is a intersection point of two line segments. Note that if the intersection is a line segment, this method only tests for equality with the endpoints of the intersection segment. It does not return true if the input point is internal to the intersection segment.
    
    Returns:
    
    true if the input point is one of the intersection points.
  - isInteriorIntersection
```
public boolean isInteriorIntersection()
```
    Tests whether either intersection point is an interior point of one of the input segments.
    
    Returns:
    
    true if either intersection point is in the interior of one of the input segments
  - isInteriorIntersection
```
public boolean isInteriorIntersection(int inputLineIndex)
```
    Tests whether either intersection point is an interior point of the specified input segment.
    
    Returns:
    
    true if either intersection point is in the interior of the input segment
  - isProper
```
public boolean isProper()
```
    Tests whether an intersection is proper.
    The intersection between two line segments is considered proper if they intersect in a single point in the interior of both segments (e.g. the intersection is a single point and is not equal to any of the endpoints).
    The intersection between a point and a line segment is considered proper if the point lies in the interior of the segment (e.g. is not equal to either of the endpoints).
    
    Returns:
    
    true if the intersection is proper
  - getIntersectionAlongSegment
```
public Coordinate getIntersectionAlongSegment(int segmentIndex,
                                              int intIndex)
```
    Computes the intIndex'th intersection point in the direction of a specified input line segment
    
    Parameters:
    
    segmentIndex - is 0 or 1
    
    intIndex - is 0 or 1
    
    Returns:
    
    the intIndex'th intersection point in the direction of the specified input line segment
  - getIndexAlongSegment
```
public int getIndexAlongSegment(int segmentIndex,
                                int intIndex)
```
    Computes the index (order) of the intIndex'th intersection point in the direction of a specified input line segment
    
    Parameters:
    
    segmentIndex - is 0 or 1
    
    intIndex - is 0 or 1
    
    Returns:
    
    the index of the intersection point along the input segment (0 or 1)
  - computeIntLineIndex
```
protected void computeIntLineIndex(int segmentIndex)
```
  - getEdgeDistance
```
public double getEdgeDistance(int segmentIndex,
                              int intIndex)
```
    Computes the "edge distance" of an intersection point along the specified input line segment.
    
    Parameters:
    
    segmentIndex - is 0 or 1
    
    intIndex - is 0 or 1
    
    Returns:
    
    the edge distance of the intersection point

Class LineIntersector

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DONT_INTERSECT

DO_INTERSECT

COLLINEAR

NO_INTERSECTION

POINT_INTERSECTION

COLLINEAR_INTERSECTION

result

inputLines

intPt

intLineIndex

isProper

pa

pb

precisionModel

Constructor Detail

LineIntersector

Method Detail

computeEdgeDistance

nonRobustComputeEdgeDistance

setMakePrecise

setPrecisionModel

getEndpoint

computeIntersection

isCollinear

computeIntersection

computeIntersect

toString

isEndPoint

hasIntersection

getIntersectionNum

getIntersection

computeIntLineIndex

isIntersection

isInteriorIntersection

isInteriorIntersection

isProper

getIntersectionAlongSegment

getIndexAlongSegment

computeIntLineIndex

getEdgeDistance