LineI (tektosyne API)

java.lang.Object
- org.kynosarges.tektosyne.geometry.LineI

```
public final class LineI
extends java.lang.Object
```
Represents a directed line segment in two-dimensional space, using Integer coordinates. LineI contains two immutable PointI locations, indicating the start and end points of a directed line segment. angle() and length() are calculated on demand. Use LineD to represent lines with Double coordinates.

Field Summary

Fields
Modifier and Type Field and Description

static LineI EMPTY
An empty read-only LineI.

PointI end
The end point of the LineI.

PointI start
The start point of the LineI.

Fields
Modifier and Type	Field and Description
`static LineI`	`EMPTY` An empty read-only `LineI`.
`PointI`	`end` The end point of the `LineI`.
`PointI`	`start` The start point of the `LineI`.

Constructor Summary

Constructors
Constructor and Description
`LineI()` Creates a `LineI` that starts and ends at the coordinate origin.
`LineI(int startX, int startY, int endX, int endY)` Creates a `LineI` with the specified `Integer` coordinates.
`LineI(PointI start, PointI end)` Creates a `LineI` with the specified `PointI` coordinates.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`double`	`angle()` Gets the angle of the `LineI`, in radians.
`double`	`distanceSquared(PointI q)` Gets the squared distance between the `LineI` and the specified `PointI` coordinates.
`boolean`	`equals(java.lang.Object obj)` Compares the specified `Object` to this `LineI` instance.
`double`	`findX(double y)` Finds the x-coordinate for the specified y-coordinate on the `LineI` or its infinite extension.
`double`	`findY(double x)` Finds the y-coordinate for the specified x-coordinate on the `LineI` or its infinite extension.
`static LineI[]`	`fromInts(int... lines)` Converts the specified `Integer` array to a `LineI` array.
`int`	`hashCode()` Returns a hash code for the `LineI`.
`LineIntersection`	`intersect(LineI line)` Finds the intersection between the `LineI` and a specified instance.
`PointD`	`intersect(PointI q)` Finds the intersection between the `LineI` and the perpendicular dropped from the specified `PointI` coordinates.
`double`	`inverseSlope()` Gets the inverse slope of the `LineI`.
`double`	`length()` Gets the absolute length of the `LineI`.
`long`	`lengthSquared()` Gets the squared absolute length of the `LineI`.
`LineLocation`	`locate(PointI q)` Determines the location of the specified `PointI` relative to the `LineI`.
`LineLocation`	`locateCollinear(PointI q)` Determines the location of the specified `PointI` relative to the `LineI`, assuming they are collinear.
`LineI`	`reverse()` Reverses the direction of the `LineI`.
`double`	`slope()` Gets the slope of the `LineI`.
`static int[]`	`toInts(LineI... lines)` Converts the specified `LineI` array to an `Integer` array.
`LineD`	`toLineD()` Converts the `LineI` to a `LineD`.
`java.lang.String`	`toString()` Returns a `String` representation of the `LineI`.
`PointI`	`vector()` Gets the vector defined by the `LineI`.

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

- Field Detail
  - start
```
public final PointI start
```
    The start point of the LineI.
  - end
```
public final PointI end
```
    The end point of the LineI.
  - EMPTY
```
public static final LineI EMPTY
```
    An empty read-only LineI. Both start and end are set to PointI.EMPTY.
- Constructor Detail
  - LineI
```
public LineI()
```
    Creates a LineI that starts and ends at the coordinate origin. Both start and end are set to PointI.EMPTY.
  - LineI
```
public LineI(int startX,
             int startY,
             int endX,
             int endY)
```
    Creates a LineI with the specified Integer coordinates.
    
    Parameters:
    
    startX - the x-coordinate of the start point
    
    startY - the y-coordinate of the start point
    
    endX - the x-coordinate of the end point
    
    endY - the y-coordinate of the end point
  - LineI
```
public LineI(PointI start,
             PointI end)
```
    Creates a LineI with the specified PointI coordinates.
    
    Parameters:
    
    start - the start point of the LineI
    
    end - the end point of the LineI
    
    Throws:
    
    java.lang.NullPointerException - if start or end is null
- Method Detail
  - angle
```
public double angle()
```
    Gets the angle of the LineI, in radians. Returns the result of Math.atan2(double, double) for the vertical and horizontal distances between end and start, within the interval [-Math.PI, +Math.PI].
    angle() equals zero if the LineI extends horizontally to the right, and increases as the line turns clockwise (y-axis pointing down) or counter-clockwise (y-axis pointing up).
    
    Returns:
    
    the angle, in radians, of the direction on the Cartesian plane in which the LineI is pointing, or zero if length() equals zero
  - distanceSquared
```
public double distanceSquared(PointI q)
```
    Gets the squared distance between the LineI and the specified PointI coordinates. Returns either the squared length of the perpendicular dropped from q on the LineI, or the squared distance between q and start or end if the perpendicular does not intersect the LineI.
    
    Parameters:
    
    q - the PointI coordinates to examine
    
    Returns:
    
    the squared distance between the LineI and q
    
    Throws:
    
    java.lang.NullPointerException - if q is null
  - findX
```
public double findX(double y)
```
    Finds the x-coordinate for the specified y-coordinate on the LineI or its infinite extension. Returns the PointI.x coordinate of start or end if y exactly equals the corresponding PointI.y coordinate, else a computed x-coordinate.
    
    Parameters:
    
    y - the y-coordinate to examine
    
    Returns:
    
    the x-coordinate for y on the LineI or its infinite extension, or Double.MAX_VALUE if the LineI is horizontal
  - findY
```
public double findY(double x)
```
    Finds the y-coordinate for the specified x-coordinate on the LineI or its infinite extension. Returns the PointI.y coordinate of start or end if x exactly equals the corresponding PointI.x coordinate, else a computed y-coordinate.
    
    Parameters:
    
    x - the x-coordinate to examine
    
    Returns:
    
    the y-coordinate for x on the LineI or its infinite extension, or Double.MAX_VALUE if the LineI is vertical
  - fromInts
```
public static LineI[] fromInts(int... lines)
```
    Converts the specified Integer array to a LineI array. The returned array has a quarter as many elements as the specified lines and retains the same coordinate sequence.
    
    Parameters:
    
    lines - an array containing the coordinates start.x, start.y, end.x, end.y of LineI instances, stored in successive index positions per LineI
    
    Returns:
    
    the LineI array created from lines
    
    Throws:
    
    java.lang.IllegalArgumentException - if the length of lines is not divisible by four
    
    java.lang.NullPointerException - if lines is null
  - intersect
```
public LineIntersection intersect(LineI line)
```
    Finds the intersection between the LineI and a specified instance. Returns the result of LineIntersection.find(org.kynosarges.tektosyne.geometry.PointD, org.kynosarges.tektosyne.geometry.PointD, org.kynosarges.tektosyne.geometry.PointD, org.kynosarges.tektosyne.geometry.PointD) for the start and end points of this instance and the specified line, in that order.
    
    Parameters:
    
    line - the LineI to intersect with this instance
    
    Returns:
    
    a LineIntersection that describes if and how this instance intersects the specified line
    
    Throws:
    
    java.lang.NullPointerException - if line is null
  - intersect
```
public PointD intersect(PointI q)
```
    Finds the intersection between the LineI and the perpendicular dropped from the specified PointI coordinates. Returns start if length() equals zero.
    
    Parameters:
    
    q - the PointI coordinates from which to drop the perpendicular
    
    Returns:
    
    the PointD location where the perpendicular dropped from q intersects the LineI or its infinite extension
    
    Throws:
    
    java.lang.NullPointerException - if q is null
  - inverseSlope
```
public double inverseSlope()
```
    Gets the inverse slope of the LineI. Equals 1/slope(). May return a negative value, depending on angle().
    
    Returns:
    
    the quotient of the horizontal and vertical extensions of the LineI, or Double.MAX_VALUE if the LineI is horizontal
  - length
```
public double length()
```
    Gets the absolute length of the LineI. Returns the square root of the sum of the squares of the horizontal and vertical extensions of the LineI.
    
    Returns:
    
    the non-negative absolute length of the LineI
  - lengthSquared
```
public long lengthSquared()
```
    Gets the squared absolute length of the LineI. Returns the sum of the squares of the horizontal and vertical extensions of the LineI, widened to Long to avoid Integer overflow. Use instead of length() if you only need the squared value.
    
    Returns:
    
    a non-negative Long value that equals the square of length()
  - locate
```
public LineLocation locate(PointI q)
```
    Determines the location of the specified PointI relative to the LineI. Never returns null. The return values LineLocation.LEFT and LineLocation.RIGHT assume that y-coordinates increase upward.
    locate is based on the classify algorithm by Michael J. Laszlo, Computational Geometry and Computer Graphics in C++, Prentice Hall 1996, p.76.
    
    Parameters:
    
    q - the PointI coordinates to examine
    
    Returns:
    
    a LineLocation value indicating the location of q relative to the LineI
    
    Throws:
    
    java.lang.NullPointerException - if q is null
  - locateCollinear
```
public LineLocation locateCollinear(PointI q)
```
    Determines the location of the specified PointI relative to the LineI, assuming they are collinear. Returns the result of LineIntersection.locateCollinear(org.kynosarges.tektosyne.geometry.PointD, org.kynosarges.tektosyne.geometry.PointD, org.kynosarges.tektosyne.geometry.PointD) for the start and end points of this instance and the specified q, in that order. Never returns null, LineLocation.LEFT, or LineLocation.RIGHT due to the assumption of collinearity.
    
    Parameters:
    
    q - the PointI coordinates to examine
    
    Returns:
    
    a LineLocation value indicating the location of q relative to the LineI
    
    Throws:
    
    java.lang.NullPointerException - if q is null
  - reverse
```
public LineI reverse()
```
    Reverses the direction of the LineI.
    
    Returns:
    
    a LineI whose start equals the end of this instance, and vice versa
  - slope
```
public double slope()
```
    Gets the slope of the LineI. Equals 1/inverseSlope(). May return a negative value, depending on angle().
    
    Returns:
    
    the quotient of the vertical and horizontal extensions of the LineI, or Double.MAX_VALUE if the LineI is vertical
  - toInts
```
public static int[] toInts(LineI... lines)
```
    Converts the specified LineI array to an Integer array. The returned array has four times as many elements as the specified lines and retains the same coordinate sequence.
    
    Parameters:
    
    lines - the LineI array to convert
    
    Returns:
    
    an array containing the coordinates start.x, start.y, end.x, end.y for all lines, stored in successive index positions per LineI
    
    Throws:
    
    java.lang.NullPointerException - if lines or any of its elements is null
  - toLineD
```
public LineD toLineD()
```
    Converts the LineI to a LineD.
    
    Returns:
    
    a LineD whose LineD.start and LineD.end points equal the corresponding points of the LineI
  - vector
```
public PointI vector()
```
    Gets the vector defined by the LineI. Equals the end point of the LineI, assuming its start point was shifted to the coordinate origin.
    
    Returns:
    
    a PointI vector comprising the horizontal and vertical extensions of the LineI
    
    Throws:
    
    java.lang.ArithmeticException - if the difference in any dimension overflows Integer
  - equals
```
public boolean equals(java.lang.Object obj)
```
    Compares the specified Object to this LineI instance.
    
    Overrides:
    
    equals in class java.lang.Object
    
    Parameters:
    
    obj - the Object to compare to this instance
    
    Returns:
    
    true if obj is not null and a LineI instance whose start and end equal those of this instance, else false
  - hashCode
```
public int hashCode()
```
    Returns a hash code for the LineI.
    
    Overrides:
    
    hashCode in class java.lang.Object
    
    Returns:
    
    an Integer hash code for the LineI
  - toString
```
public java.lang.String toString()
```
    Returns a String representation of the LineI.
    
    Overrides:
    
    toString in class java.lang.Object
    
    Returns:
    
    a String containing the values of start and end

Class LineI

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

start

end

EMPTY

Constructor Detail

LineI

LineI

LineI

Method Detail

angle

distanceSquared

findX

findY

fromInts

intersect

intersect

inverseSlope

length

lengthSquared

locate

locateCollinear

reverse

slope

toInts

toLineD

vector

equals

hashCode

toString