city.cs.engine

Class SolidFixture

java.lang.Object

city.cs.engine.Fixture

city.cs.engine.SolidFixture

public class SolidFixture
extends Fixture

A component of a rigid body. A body can have multiple fixtures but fixtures cannot be shared among multiple bodies.

Constructor Summary

Constructors

Constructor and Description
SolidFixture(Body body, Shape shape) Create a fixture from a shape.
SolidFixture(Body body, Shape shape, float density) Create a fixture from a shape.

Method Summary

Modifier and Type	Method and Description
float	getFriction() The current coefficient of friction for this fixture.
float	getRestitution() The current coefficient of restitution for this shape.
void	setFriction(float friction) Set the coefficient of friction for this shape.
void	setRestitution(float restitution) Set the coefficient of restitution (bounciness) for this fixture.

Methods inherited from class city.cs.engine.Fixture

contains, destroy, getBody, getDensity, intersects, intersects, setDensity

Methods inherited from class java.lang.Object

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

Constructor Detail

SolidFixture

public SolidFixture(Body body,
                    Shape shape)

Create a fixture from a shape. Defaults: friction = 0.2, restitution = 0.0, density = 1.0.

Parameters:

body - the body the fixture is part of

shape - the shape of the fixture

SolidFixture

public SolidFixture(Body body,
                    Shape shape,
                    float density)

Create a fixture from a shape. Defaults: friction = 0.2, restitution = 0.0.

Parameters:

body - the body the fixture is part of

shape - the shape of the fixture

density - the density of the fixture (in kg/square metre)

Method Detail

setFriction

public void setFriction(float friction)

Set the coefficient of friction for this shape. When two bodies are pushed together, there is a force (friction) that limits the extent that they can slide along each other, and this force is limited to a certain fraction of the force pushing the two bodies together.

This proportion is the coefficient of friction, and it depends on the nature of the two bodies. A value of 0 means no friction, higher values mean more friction. A value of 1 is very strong but even higher values are allowed. For example ice would have a coefficient of friction close to zero, while rubber would have a high value.

The effective friction between two shapes is calculated using the geometric mean: sqrt(f1 * f2). Thus if one of the fixtures has zero friction, the contact will have no friction.

Parameters:

friction - the new friction coefficient for this fixture

getFriction

public float getFriction()

The current coefficient of friction for this fixture.

Returns:

the friction coefficient

setRestitution

public void setRestitution(float restitution)

Set the coefficient of restitution (bounciness) for this fixture. The coefficient of restitution is a number between 0 and 1. A value of 0 means no bounce (inelastic collision), a value of 1 means perfect bounce (perfectly elastic collision). Values higher than 1 result in impossible behaviour, in that the total energy of the associated bodies effectively increases as a result of their colliding. The effective restitution between two fixtures is taken to be the maximum of their two restitutions.

Parameters:

restitution - the new restitution coefficient for this shape

getRestitution

public float getRestitution()

The current coefficient of restitution for this shape.

Returns:

the restitution coefficient