org.jbox2d.collision.shapes

Class PolygonShape

java.lang.Object

org.jbox2d.collision.shapes.Shape

org.jbox2d.collision.shapes.PolygonShape

public class PolygonShape
extends Shape

A convex polygon shape. Polygons have a maximum number of vertices equal to _maxPolygonVertices. In most cases you should not need many vertices for a convex polygon.

Field Summary

Fields

Modifier and Type	Field and Description
Vec2	m_centroid Local position of the shape centroid in parent body frame.
int	m_count Number of active vertices in the shape.
Vec2[]	m_normals The normals of the shape.
Vec2[]	m_vertices The vertices of the shape.

Fields inherited from class org.jbox2d.collision.shapes.Shape

m_radius, m_type

Constructor Summary

Constructors

Constructor and Description
PolygonShape()

Method Summary

Modifier and Type	Method and Description
Vec2	centroid(Transform xf) Get the centroid and apply the supplied transform.
Vec2	centroidToOut(Transform xf, Vec2 out) Get the centroid and apply the supplied transform.
Shape	clone()
void	computeAABB(AABB aabb, Transform xf, int childIndex) Given a transform, compute the associated axis aligned bounding box for a child shape.
void	computeCentroidToOut(Vec2[] vs, int count, Vec2 out)
void	computeMass(MassData massData, float density) Compute the mass properties of this shape using its dimensions and density.
int	getChildCount() Get the number of child primitives
Vec2[]	getNormals() Get the edge normal vectors.
Vec2	getVertex(int index) Get a vertex by index.
int	getVertexCount() Get the vertex count.
Vec2[]	getVertices() Get the vertices in local coordinates.
boolean	raycast(RayCastOutput output, RayCastInput input, Transform xf, int childIndex) Cast a ray against a child shape.
void	set(Vec2[] vertices, int count) Create a convex hull from the given array of points.
void	set(Vec2[] verts, int num, Vec2Array vecPool, IntArray intPool) Create a convex hull from the given array of points.
void	setAsBox(float hx, float hy) Build vertices to represent an axis-aligned box.
void	setAsBox(float hx, float hy, Vec2 center, float angle) Build vertices to represent an oriented box.
boolean	testPoint(Transform xf, Vec2 p) Test a point for containment in this shape.
boolean	validate() Validate convexity.

Methods inherited from class org.jbox2d.collision.shapes.Shape

getRadius, getType, setRadius

Methods inherited from class java.lang.Object

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

Field Detail

m_centroid

public final Vec2 m_centroid

Local position of the shape centroid in parent body frame.

m_vertices

public final Vec2[] m_vertices

The vertices of the shape. Note: use getVertexCount(), not m_vertices.length, to get number of active vertices.

m_normals

public final Vec2[] m_normals

The normals of the shape. Note: use getVertexCount(), not m_normals.length, to get number of active normals.

m_count

public int m_count

Number of active vertices in the shape.

Constructor Detail

PolygonShape

public PolygonShape()

Method Detail

clone

public final Shape clone()

Specified by:

clone in class Shape

set

public final void set(Vec2[] vertices,
                      int count)

Create a convex hull from the given array of points. The count must be in the range [3, Settings.maxPolygonVertices].

set

public final void set(Vec2[] verts,
                      int num,
                      Vec2Array vecPool,
                      IntArray intPool)

Create a convex hull from the given array of points. The count must be in the range [3, Settings.maxPolygonVertices]. This method takes an arraypool for pooling

setAsBox

public final void setAsBox(float hx,
                           float hy)

Build vertices to represent an axis-aligned box.

Parameters:

hx - the half-width.

hy - the half-height.

setAsBox

public final void setAsBox(float hx,
                           float hy,
                           Vec2 center,
                           float angle)

Build vertices to represent an oriented box.

Parameters:

hx - the half-width.

hy - the half-height.

center - the center of the box in local coordinates.

angle - the rotation of the box in local coordinates.

getChildCount

public int getChildCount()

Description copied from class: Shape

Get the number of child primitives

Specified by:

getChildCount in class Shape

Returns:

testPoint

public final boolean testPoint(Transform xf,
                               Vec2 p)

Description copied from class: Shape

Test a point for containment in this shape. This only works for convex shapes.

Specified by:

testPoint in class Shape

Parameters:

xf - the shape world transform.

p - a point in world coordinates.

computeAABB

public final void computeAABB(AABB aabb,
                              Transform xf,
                              int childIndex)

Description copied from class: Shape

Given a transform, compute the associated axis aligned bounding box for a child shape.

Specified by:

computeAABB in class Shape

getVertexCount

public final int getVertexCount()

Get the vertex count.

Returns:

getVertex

public final Vec2 getVertex(int index)

Get a vertex by index.

Parameters:

index -

Returns:

raycast

public final boolean raycast(RayCastOutput output,
                             RayCastInput input,
                             Transform xf,
                             int childIndex)

Description copied from class: Shape

Cast a ray against a child shape.

Specified by:

raycast in class Shape

Returns:

if hit

computeCentroidToOut

public final void computeCentroidToOut(Vec2[] vs,
                                       int count,
                                       Vec2 out)

computeMass

public void computeMass(MassData massData,
                        float density)

Description copied from class: Shape

Compute the mass properties of this shape using its dimensions and density. The inertia tensor is computed about the local origin.

Specified by:

computeMass in class Shape

Parameters:

massData - returns the mass data for this shape.

density - the density in kilograms per meter squared.

validate

public boolean validate()

Validate convexity. This is a very time consuming operation.

Returns:

getVertices

public Vec2[] getVertices()

Get the vertices in local coordinates.

getNormals

public Vec2[] getNormals()

Get the edge normal vectors. There is one for each vertex.

centroid

public Vec2 centroid(Transform xf)

Get the centroid and apply the supplied transform.

centroidToOut

public Vec2 centroidToOut(Transform xf,
                          Vec2 out)

Get the centroid and apply the supplied transform.