com.almasb.fxgl.physics.box2d.collision

Class Manifold

java.lang.Object

com.almasb.fxgl.physics.box2d.collision.Manifold

public class Manifold
extends Object

A manifold for two touching convex shapes. Box2D supports multiple types of contact:

• clip point versus plane with radius
• point versus point with radius (circles)

The local point usage depends on the manifold type:

• e_circles: the local center of circleA
• e_faceA: the center of faceA
• e_faceB: the center of faceB

Similarly the local normal usage:

• e_circles: not used
• e_faceA: the normal on polygonA
• e_faceB: the normal on polygonB

We store contacts in this way so that position correction can account for movement, which is critical for continuous physics. All contact scenarios must be expressed in one of these types. This structure is stored across time steps, so we keep it small.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Manifold.ManifoldType

Field Summary

Fields

Modifier and Type	Field and Description
Vec2	localNormal not use for Type::e_points
Vec2	localPoint usage depends on manifold type
int	pointCount The number of manifold points.
ManifoldPoint[]	points The points of contact.
Manifold.ManifoldType	type

Constructor Summary

Constructors

Constructor and Description
Manifold() creates a manifold with 0 points, with it's points array full of instantiated ManifoldPoints.
Manifold(Manifold other) Creates this manifold as a copy of the other

Method Summary

Modifier and Type	Method and Description
void	set(Manifold cp) copies this manifold from the given one

Methods inherited from class java.lang.Object

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

Field Detail

points

public final ManifoldPoint[] points

The points of contact.

localNormal

public final Vec2 localNormal

not use for Type::e_points

localPoint

public final Vec2 localPoint

usage depends on manifold type

type

public Manifold.ManifoldType type

pointCount

public int pointCount

The number of manifold points.

Constructor Detail

Manifold

public Manifold()

creates a manifold with 0 points, with it's points array full of instantiated ManifoldPoints.

Manifold

public Manifold(Manifold other)

Creates this manifold as a copy of the other

Parameters:

other -

Method Detail

set

public void set(Manifold cp)

copies this manifold from the given one

Parameters:

cp - manifold to copy from