PinBallDomain
Class Ball

java.lang.Object
  PinBallDomain.Ball

public class Ball
extends java.lang.Object

Object to represent the ball for the PinBall domain.

Author:

George Konidaris (gdk at cs dot umass dot edu)

Field Summary

static double

DRAG Drag coefficient

Constructor Summary

Ball(Point p, double rad)
Constructs a new ball given a point and radius.

Method Summary

void	addDrag() Applies drag to the ball.
void	addImpulse(double tox, double toy) Add a velocity impulse to the ball.
static Ball	create(java.lang.String line) Creates a ball object from a line in a config file.
Point	getCenter() Obtain the center point of the ball.
double	getRadius() Obtain the ball's radius.
double	getVelocity() Return the ball's speed.
double	getX() Obtain the ball's X co-ordinate
double	getXDot() Obtain the ball's X velocity.
double	getY() Obtain the ball's Y co-ordinate
double	getYDot() Obtain the ball's Y velocity.
static boolean	matchTag(java.lang.String line) Determines whether a config file line refers to the ball.
void	setPosition(double xx, double yy) Set the ball's position.
void	setVelocities(double dx, double dy) Explicity set the ball's velocities.
void	step() Moves the ball one step forward, in the direction of xdot and ydot.
void	write(java.io.FileWriter f) Writes the ball to a config file.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DRAG

public static final double DRAG

Drag coefficient

See Also:

Constant Field Values

Constructor Detail

Ball

public Ball(Point p,
            double rad)

Constructs a new ball given a point and radius. X and Y velocities are set to zero.

Parameters:

p - desired X and Y co-ordinates

rad - desired radius

Method Detail

getRadius

public double getRadius()

Obtain the ball's radius.

Returns:

the radius

getX

public double getX()

Obtain the ball's X co-ordinate

Returns:

the ball's X co-ordinate

getY

public double getY()

Obtain the ball's Y co-ordinate

Returns:

the ball's Y co-ordinate

getXDot

public double getXDot()

Obtain the ball's X velocity.

Returns:

the ball's X velocity.

getYDot

public double getYDot()

Obtain the ball's Y velocity.

Returns:

the ball's Y velocity.

matchTag

public static boolean matchTag(java.lang.String line)

Determines whether a config file line refers to the ball.

Parameters:

line - the text line from the config file

Returns:

true if the line refers to a ball, false otherwise

create

public static Ball create(java.lang.String line)

Creates a ball object from a line in a config file. The line should first have been matched, and is of format: "ball radius".

The line specifies the ball's radius, but not it's position, because it may have multiple potential starting positions.

Parameters:

line - the line

Returns:

a new Ball object

See Also:

Ball

write

public void write(java.io.FileWriter f)
           throws java.io.IOException

Writes the ball to a config file.

Parameters:

f - file to be written to.

Throws:

java.io.IOException

step

public void step()

Moves the ball one step forward, in the direction of xdot and ydot.

addDrag

public void addDrag()

Applies drag to the ball.

getVelocity

public double getVelocity()

Return the ball's speed.

Returns:

speed

addImpulse

public void addImpulse(double tox,
                       double toy)

Add a velocity impulse to the ball.

Parameters:

tox - impulse to add to xdot

toy - impulse to add to ydot

setVelocities

public void setVelocities(double dx,
                          double dy)

Explicity set the ball's velocities.

Parameters:

dx - X velocity

dy - Y velocity

setPosition

public void setPosition(double xx,
                        double yy)

Set the ball's position. This also halts the ball (sets its X and Y velocities to zero).

Parameters:

xx - X position

yy - Y position

getCenter

public Point getCenter()

Obtain the center point of the ball.

Returns:

the center point

See Also:

Point