org.jbox2d.common

Class Vec2

java.lang.Object

org.jbox2d.common.Vec2

All Implemented Interfaces:

Serializable

public class Vec2
extends Object
implements Serializable

A 2-dimensional vector, expressing a directional quantity in world space. A vector can be viewed in two ways:

• as a pair of numbers (Cartesian coordinates) specifying a position in space:
  • the x-coordinate, measured from left to right, and
  • the y-coordinate, measured from top to bottom, or
• as a line segment of a particular length and direction.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
float	x The x component, increasing to the right.
float	y The y component, increasing upwards.

Constructor Summary

Constructors

Constructor and Description
Vec2() A vector with x and y components both zero.
Vec2(float x, float y) A vector with the given components.

Method Summary

Modifier and Type	Method and Description
Vec2	add(Vec2 v) Return the sum of this vector and another; does not alter either one.
static float	cross(Vec2 a, Vec2 b) The z-component of the cross product of two vectors.
static float	dot(Vec2 a, Vec2 b) The dot product of two vectors.
int	hashCode() Returns a hash code value for the object for use in hash tables.
float	length() Return the length of this vector.
float	lengthSquared() Return the squared length of this vector.
Vec2	mul(float a) Return this vector multiplied by a number; does not alter this vector.
Vec2	negate() Return the negation of this vector; does not alter this vector.
float	normalize() Normalize this vector and return the length before normalization.
Vec2	sub(Vec2 v) Return the difference between this vector and another; does not alter either one.
String	toString() Return a string representation of the vector.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

x

public float x

The x component, increasing to the right.

y

public float y

The y component, increasing upwards.

Constructor Detail

Vec2

public Vec2()

A vector with x and y components both zero.

Vec2

public Vec2(float x,
            float y)

A vector with the given components.

Parameters:

x - the x component, increasing to the right

y - the y component, increasing upwards

Method Detail

add

public final Vec2 add(Vec2 v)

Return the sum of this vector and another; does not alter either one. Geometrically, vectors are added by starting one where the other ends.

Parameters:

v - a vector to be added to this one

Returns:

a new vector whose x and y components are the sums of the x and y components of this vector and v

sub

public final Vec2 sub(Vec2 v)

Return the difference between this vector and another; does not alter either one.

Parameters:

v - a vector to be added to this one

Returns:

a new vector whose x and y components are the differences between the x and y components of this vector and v

mul

public final Vec2 mul(float a)

Return this vector multiplied by a number; does not alter this vector. Geometrically, the result is a vector in the same dircetion, but with its length multiplied by a. (So if a is negative, the result will be a vector in the opposite direction.)

Parameters:

a - number to multiply the vector by

Returns:

a new vector obtained by multiplying each component of this one by a

negate

public final Vec2 negate()

Return the negation of this vector; does not alter this vector. Geometrically, the negation is a vector of the same length but in the opposite direction.

Returns:

a new vector whose x and y components are the negations of the x and y components of this vector

length

public final float length()

Return the length of this vector.

lengthSquared

public final float lengthSquared()

Return the squared length of this vector.

normalize

public final float normalize()

Normalize this vector and return the length before normalization. Alters this vector.

toString

public final String toString()

Return a string representation of the vector.

Overrides:

toString in class Object

Returns:

a string of the form (x,y)

dot

public static final float dot(Vec2 a,
                              Vec2 b)

The dot product of two vectors.

cross

public static final float cross(Vec2 a,
                                Vec2 b)

The z-component of the cross product of two vectors. This is equal to the area of the parallelogram bounded by the two vectors.

hashCode

public int hashCode()

Returns a hash code value for the object for use in hash tables.

Overrides:

hashCode in class Object