Package lejos.robotics.geometry

Class 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

    • 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 -

      • 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