Line2D

Full name Microsoft.VisualBasic.Imaging.Math2D.Line2D Assembly Microsoft.VisualBasic.Runtime Members 6

This

Line2D

represents a line segment in {@code (x,y)} coordinate space. This [Class], like all of the Java 2D API, uses a default coordinate system called user space in which the y-axis values increase downward and x-axis values increase to the right. For more information on the user space coordinate system, see the

Coordinate Systems section of the Java 2D Programmer's Guide.

This class is only the abstract superclass for all objects that store a 2D line segment. The actual storage representation of the coordinates is left to the subclass.

@author Jim Graham @since 1.2

01 Syntax

Microsoft.VisualBasic.Imaging.Math2D.Line2D

02 Methods

Name	Overloads	Summary
relativeCCW	1	Returns an indicator of where the specified point {@code (px,py)} lies with respect to the line segment from {@code (x1,y1)} to {@code (x2,y2)}.
linesIntersect	1	Tests if the line segment from {@code (x1,y1)} to {@code (x2,y2)} intersects the line segment from {@code (x3,y3)} to {@code (x4,y4)}.
ptSegDistSq	1	Returns the square of the distance from a point to a line segment.
ptSegDist	1	Returns the distance from a point to a line segment.
ptLineDistSq	1	Returns the square of the distance from a point to a line.
ptLineDist	1	Returns the distance from a point to a line.

03 Members

method relativeCCW #

relativeCCW(Double, Double, Double, Double, Double, Double)

Returns an indicator of where the specified point {@code (px,py)} lies with respect to the line segment from {@code (x1,y1)} to {@code (x2,y2)}.

The return value can be either 1, -1, or 0 and indicates in which direction the specified line must pivot around its first end point, {@code (x1,y1)}, in order to point at the specified point {@code (px,py)}.

A return value of 1 indicates that the line segment must turn in the direction that takes the positive X axis towards the negative Y axis. In the default coordinate system used by Java 2D, this direction is counterclockwise.

A return value of -1 indicates that the line segment must turn in the direction that takes the positive X axis towards the positive Y axis. In the default coordinate system, this direction is clockwise.

A return value of 0 indicates that the point lies exactly on the line segment. Note that an indicator value of 0 is rare and not useful for determining collinearity because of floating point rounding issues.

If the point is colinear with the line segment, but not between the end points, then the value will be -1 if the point lies "beyond {@code (x1,y1)}" or 1 if the point lies "beyond {@code (x2,y2)}".

Parameters

Name	Type	Description
`x1`	`Double`	the X coordinate of the start point of the specified line segment
`y1`	`Double`	the Y coordinate of the start point of the specified line segment
`x2`	`Double`	the X coordinate of the end point of the specified line segment
`y2`	`Double`	the Y coordinate of the end point of the specified line segment
`px`	`Double`	the X coordinate of the specified point to be compared with the specified line segment
`py`	`Double`	the Y coordinate of the specified point to be compared with the specified line segment

Returns

an integer that indicates the position of the third specified coordinates with respect to the line segment formed by the first two specified coordinates. @since 1.2

method linesIntersect #

linesIntersect(Double, Double, Double, Double, Double, Double, Double, Double)

Tests if the line segment from {@code (x1,y1)} to {@code (x2,y2)} intersects the line segment from {@code (x3,y3)} to {@code (x4,y4)}.

Parameters

Name	Type	Description
`x1`	`Double`	the X coordinate of the start point of the first specified line segment
`y1`	`Double`	the Y coordinate of the start point of the first specified line segment
`x2`	`Double`	the X coordinate of the end point of the first specified line segment
`y2`	`Double`	the Y coordinate of the end point of the first specified line segment
`x3`	`Double`	the X coordinate of the start point of the second specified line segment
`y3`	`Double`	the Y coordinate of the start point of the second specified line segment
`x4`	`Double`	the X coordinate of the end point of the second specified line segment
`y4`	`Double`	the Y coordinate of the end point of the second specified line segment

Returns

true

if the first specified line segment and the second specified line segment intersect each other;

false

otherwise. @since 1.2

method ptSegDistSq #

ptSegDistSq(Double, Double, Double, Double, Double, Double)

Returns the square of the distance from a point to a line segment. The distance measured is the distance between the specified point and the closest point between the specified end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.

Parameters

Name	Type	Description
`x1`	`Double`	the X coordinate of the start point of the specified line segment
`y1`	`Double`	the Y coordinate of the start point of the specified line segment
`x2`	`Double`	the X coordinate of the end point of the specified line segment
`y2`	`Double`	the Y coordinate of the end point of the specified line segment
`px`	`Double`	the X coordinate of the specified point being measured against the specified line segment
`py`	`Double`	the Y coordinate of the specified point being measured against the specified line segment

Returns

a double value that is the square of the distance from the specified point to the specified line segment.

method ptSegDist #

ptSegDist(Double, Double, Double, Double, Double, Double)

Returns the distance from a point to a line segment. The distance measured is the distance between the specified point and the closest point between the specified end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.

Parameters

Name	Type	Description
`x1`	`Double`	the X coordinate of the start point of the specified line segment
`y1`	`Double`	the Y coordinate of the start point of the specified line segment
`x2`	`Double`	the X coordinate of the end point of the specified line segment
`y2`	`Double`	the Y coordinate of the end point of the specified line segment
`px`	`Double`	the X coordinate of the specified point being measured against the specified line segment
`py`	`Double`	the Y coordinate of the specified point being measured against the specified line segment

Returns

a double value that is the distance from the specified point to the specified line segment.

method ptLineDistSq #

ptLineDistSq(Double, Double, Double, Double, Double, Double)

Returns the square of the distance from a point to a line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by the specified coordinates. If the specified point intersects the line, this method returns 0.0.

Parameters

Name	Type	Description
`x1`	`Double`	the X coordinate of the start point of the specified line
`y1`	`Double`	the Y coordinate of the start point of the specified line
`x2`	`Double`	the X coordinate of the end point of the specified line
`y2`	`Double`	the Y coordinate of the end point of the specified line
`px`	`Double`	the X coordinate of the specified point being measured against the specified line
`py`	`Double`	the Y coordinate of the specified point being measured against the specified line

Returns

a double value that is the square of the distance from the specified point to the specified line.

method ptLineDist #

ptLineDist(Double, Double, Double, Double, Double, Double)

Returns the distance from a point to a line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by the specified coordinates. If the specified point intersects the line, this method returns 0.0.

Parameters

Name	Type	Description
`x1`	`Double`	the X coordinate of the start point of the specified line
`y1`	`Double`	the Y coordinate of the start point of the specified line
`x2`	`Double`	the X coordinate of the end point of the specified line
`y2`	`Double`	the Y coordinate of the end point of the specified line
`px`	`Double`	the X coordinate of the specified point being measured against the specified line
`py`	`Double`	the Y coordinate of the specified point being measured against the specified line

Returns

a double value that is the distance from the specified point to the specified line.