lejos.robotics.geometry

Class Point

java.lang.Object

lejos.robotics.geometry.Point2D

lejos.robotics.geometry.Point2D.Float

lejos.robotics.geometry.Point

All Implemented Interfaces:

java.lang.Cloneable

Direct Known Subclasses:

Waypoint

public class Point
extends Point2D.Float

Point with float co-ordinates for use in navigation. This class includes methods allow it to behave as a vector in 2 dimensional vector space. It includes the standard vector arithmetic operatins of addition, * subtraction, scalar multiplication, and inner product.

Author:

Lawrie Griffiths , Roger Glassey

Nested Class Summary

Nested classes/interfaces inherited from class lejos.robotics.geometry.Point2D

Point2D.Double, Point2D.Float

Field Summary

Fields inherited from class lejos.robotics.geometry.Point2D.Float

x, y

Constructor Summary

Constructors

Constructor and Description
Point(float radians) Returns a point ad distance 1 from the origin and an angle radans to the x-axis
Point(float x, float y) returns a Point at location x,y

Method Summary

Modifier and Type	Method and Description
Point	add(Point other) Returns the vector sum of this and other
Point	addWith(Point other) Vector addition; add other to this
float	angle() returns the angle in radians of this point from the origin.
float	angleTo(Point p) Returns the direction angle from this point to the Point p
Point	clone() returns a clone of itself
Point	copyTo(Point p)
float	dotProduct(Point other) Returns the inner dot product.
Point	getNormalized() get a copy of this with length 1
Point	leftOrth() calculate left orthogonal vector of this
float	length() Returns the length of this vector
Point	makeLeftOrth() Turns this vector into its left-handed cartesian orthagonal
Point	makeRightOrth() Turns this vector into its right-handed cartesian orthagonal
void	moveTo(Point other) Makes this a copy of the other point
Point	multiply(float scale) Scalar multiplication
Point	multiplyBy(float scale) scalar multiplication
Point	normalize() Sets this vector's length to 1 unit while retaining direction
Point	pointAt(float distance, float angle) Returns a new point at the specified distance in the direction angle from this point.
Point	projectOn(Line line) Finds the orthogonal projection of this point onto the line.
Point	reverse() same as multiply(-1);
Point	rightOrth() calculate the right handed cartesian orthogonal of this poiont
Point	subtract(float length) Vector subtraction
Point	subtract(Point other) Vector subtraction
Point	subtractWith(Point other) vector subtraction
void	translate(float dx, float dy) Translates this point, at location (x, y), by dx along the x axis and dy along the y axis so that it now represents the point (x + dx, y + dy).

Methods inherited from class lejos.robotics.geometry.Point2D.Float

getX, getY, setLocation, setLocation, toString

Methods inherited from class lejos.robotics.geometry.Point2D

distance, distance, distance, distanceSq, distanceSq, distanceSq, equals, setLocation

Methods inherited from class java.lang.Object

finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Point

public Point(float x,
             float y)

returns a Point at location x,y

Parameters:

x - coordinate

y - coordinate

Point

public Point(float radians)

Returns a point ad distance 1 from the origin and an angle radans to the x-axis

Parameters:

radians -

Method Detail

angleTo

public float angleTo(Point p)

Returns the direction angle from this point to the Point p

Parameters:

p - the Point to determine the angle to

Returns:

the angle in degrees

translate

public void translate(float dx,
                      float dy)

Translates this point, at location (x, y), by dx along the x axis and dy along the y axis so that it now represents the point (x + dx, y + dy).

Parameters:

dx -

dy -

copyTo

public Point copyTo(Point p)

clone

public Point clone()

returns a clone of itself

Overrides:

clone in class Point2D

Returns:

clone of this point

add

public Point add(Point other)

Returns the vector sum of this and other

Parameters:

other - the point added to this

Returns:

vector sum

addWith

public Point addWith(Point other)

Vector addition; add other to this

Parameters:

other - is added to this

Returns:

this after the addition

moveTo

public void moveTo(Point other)

Makes this a copy of the other point

Parameters:

other -

subtract

public Point subtract(Point other)

Vector subtraction

Parameters:

other - is subtracted from this

Returns:

a new point; this point is unchanged

subtract

public Point subtract(float length)

Vector subtraction

Parameters:

length - of a copy of this

Returns:

a new vector, obtained b subtracting a scaled version of this point

multiply

public Point multiply(float scale)

Scalar multiplication

Parameters:

scale - multilies the length of this to give a new length

Returns:

a new copy of this, with length scaled

getNormalized

public Point getNormalized()

get a copy of this with length 1

Returns:

a new vector of unit length

reverse

public Point reverse()

same as multiply(-1);

Returns:

this pointing in the opposite direction

projectOn

public Point projectOn(Line line)

Finds the orthogonal projection of this point onto the line. The projection may lie on an extension of the line

Parameters:

line - onto which the projection is made

Returns:

the projection

angle

public float angle()

returns the angle in radians of this point from the origin. The X- axis ie at angle 0.

Returns:

the angle in radians

leftOrth

public Point leftOrth()

calculate left orthogonal vector of this

Returns:

orthogonal vector

rightOrth

public Point rightOrth()

calculate the right handed cartesian orthogonal of this poiont

Returns:

orthogonal vector

subtractWith

public Point subtractWith(Point other)

vector subtraction

Parameters:

other - is subtracted from this

Returns:

this point after subtraction

multiplyBy

public Point multiplyBy(float scale)

scalar multiplication

Parameters:

scale -

Returns:

scaled this point after multiplication

length

public float length()

Returns the length of this vector

Returns:

the length

normalize

public Point normalize()

Sets this vector's length to 1 unit while retaining direction

Returns:

this vector normalized

makeLeftOrth

public Point makeLeftOrth()

Turns this vector into its left-handed cartesian orthagonal

makeRightOrth

public Point makeRightOrth()

Turns this vector into its right-handed cartesian orthagonal

dotProduct

public float dotProduct(Point other)

Returns the inner dot product.

Returns:

dot product of this with other

pointAt

public Point pointAt(float distance,
                     float angle)

Returns a new point at the specified distance in the direction angle from this point.

Parameters:

distance - the distance to the new point

angle - the angle to the new point

Returns:

the new point