Polygon shape. More...

#include <PolygonShape.hpp>

Inheritance diagram for box2d::PolygonShape:

Classes
struct	Conf

Public Types
using	vertex_count_t = std::uint8_t
	Vertex count type. More...

Public Member Functions
	PolygonShape (const Conf &conf=GetDefaultConf()) noexcept
	Default constructor. More...

	PolygonShape (const PolygonShape &)=default

	PolygonShape (Length hx, Length hy, const Conf &conf=GetDefaultConf()) noexcept
	Initializing constructor for rectangles. More...

	PolygonShape (Span< const Length2D > points, const Conf &conf=GetDefaultConf()) noexcept
	Creates a convex hull from the given array of local points. The size of the span must be in the range [1, MaxShapeVertices]. More...

child_count_t	GetChildCount () const noexcept override
	Gets the number of child primitives. More...

DistanceProxy	GetChild (child_count_t index) const noexcept override
	Gets the child for the given index. More...

bool	TestPoint (const Transformation &xf, const Length2D p) const noexcept override
	Tests a point for containment in this shape. More...

MassData	GetMassData () const noexcept override
	Computes the mass properties of this shape using its dimensions and density. The inertia tensor is computed about the local origin. More...

RayCastOutput	RayCast (const RayCastInput &input, const Transformation &xf, child_count_t childIndex) const noexcept override
	Cast a ray against a child shape. More...

void	Accept (Visitor &visitor) const override
	Accepts a visitor. More...

void	Set (Span< const Length2D > points) noexcept
	Creates a convex hull from the given array of local points. The size of the span must be in the range [1, MaxShapeVertices]. More...

void	Set (const VertexSet &points) noexcept
	Creates a convex hull from the given set of local points. The size of the set must be in the range [1, MaxShapeVertices]. More...

void	SetAsBox (Length hx, Length hy) noexcept
	Build vertices to represent an axis-aligned box centered on the local origin. More...

void	Transform (Transformation xfm) noexcept

vertex_count_t	GetVertexCount () const noexcept
	Gets the vertex count. More...

Length2D	GetVertex (vertex_count_t index) const
	Gets a vertex by index. More...

UnitVec2	GetNormal (vertex_count_t index) const
	Gets a normal by index. More...

Span< const Length2D >	GetVertices () const noexcept
	Gets the span of vertices. More...

Span< const UnitVec2 >	GetNormals () const noexcept

Length2D	GetCentroid () const noexcept

Public Member Functions inherited from box2d::Shape
	Shape ()=delete
	Default constructor is deleted. More...

	Shape (const Conf &conf) noexcept
	Initializing constructor. More...

	Shape (const Shape &)=default

virtual	~Shape ()=default

Length	GetVertexRadius () const noexcept
	Gets the vertex radius. More...

void	SetVertexRadius (Length vertexRadius)

Density	GetDensity () const noexcept
	Gets the density of this fixture. More...

void	SetDensity (Density density) noexcept
	Sets the density of this fixture. More...

RealNum	GetFriction () const noexcept
	Gets the coefficient of friction. More...

void	SetFriction (RealNum friction) noexcept
	Sets the coefficient of friction. This will not change the friction of existing contacts. More...

RealNum	GetRestitution () const noexcept
	Gets the coefficient of restitution. More...

void	SetRestitution (RealNum restitution) noexcept
	Sets the coefficient of restitution. This will not change the restitution of existing contacts. More...

Static Public Member Functions
static constexpr Length	GetDefaultVertexRadius () noexcept

static constexpr Conf	GetDefaultConf () noexcept

Static Public Attributes
static constexpr auto	InvalidVertex = static_cast<vertex_count_t>(-1)

Detailed Description

Polygon shape.

A convex polygon. The interior of the polygon is to the left of each edge. Polygons have a maximum number of vertices equal to MaxShapeVertices. In most cases you should not need many vertices for a convex polygon.

Note: This data structure is 64-bytes large (with 4-byte RealNum).

Member Typedef Documentation

◆ vertex_count_t

using box2d::PolygonShape::vertex_count_t = std::uint8_t

Vertex count type.

Note: This type must not support more than 255 vertices as that would conflict with the ContactFeature::index_t type.

Constructor & Destructor Documentation

◆ PolygonShape() [1/4]

box2d::PolygonShape::PolygonShape ( const Conf & conf = GetDefaultConf() )

inlineexplicitnoexcept

Default constructor.

Constructs a polygon shape with a 0,0 centroid and vertex count of 0.

Note: Polygons with a vertex count less than 1 are "degenerate" and should be treated as invalid.

◆ PolygonShape() [2/4]

box2d::PolygonShape::PolygonShape ( const PolygonShape & )

default

◆ PolygonShape() [3/4]

PolygonShape::PolygonShape	(	Length	hx,
		Length	hy,
		const Conf &	conf = `GetDefaultConf()`
	)

explicitnoexcept

Initializing constructor for rectangles.

Parameters

hx	the half-width.
hy	the half-height.
conf	Configuration data for the shape.

◆ PolygonShape() [4/4]

PolygonShape::PolygonShape	(	Span< const Length2D >	points,
		const Conf &	conf = `GetDefaultConf()`
	)

explicitnoexcept

Creates a convex hull from the given array of local points. The size of the span must be in the range [1, MaxShapeVertices].

Warning: the points may be re-ordered, even if they form a convex polygon; collinear points are handled but not removed. Collinear points may lead to poor stacking behavior.

Member Function Documentation

◆ Accept()

void box2d::PolygonShape::Accept ( Visitor & visitor ) const

inlineoverridevirtual

Accepts a visitor.

Implements box2d::Shape.

◆ GetCentroid()

Length2D box2d::PolygonShape::GetCentroid ( ) const

inlinenoexcept

◆ GetChild()

DistanceProxy box2d::PolygonShape::GetChild ( child_count_t index ) const

inlineoverridevirtualnoexcept

Gets the child for the given index.

Note: The shape must remain in scope while the proxy is in use.

Implements box2d::Shape.

◆ GetChildCount()

child_count_t box2d::PolygonShape::GetChildCount ( ) const

inlineoverridevirtualnoexcept

Gets the number of child primitives.

Returns: Positive non-zero count.

Implements box2d::Shape.

◆ GetDefaultConf()

static constexpr Conf box2d::PolygonShape::GetDefaultConf ( )

inlinestaticnoexcept

◆ GetDefaultVertexRadius()

static constexpr Length box2d::PolygonShape::GetDefaultVertexRadius ( )

inlinestaticnoexcept

◆ GetMassData()

MassData PolygonShape::GetMassData ( ) const

overridevirtualnoexcept

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

Note: Behavior is undefined if the density is negative.

Returns: Mass data for this shape.

Implements box2d::Shape.

◆ GetNormal()

UnitVec2 box2d::PolygonShape::GetNormal ( vertex_count_t index ) const

inline

Gets a normal by index.

These are 90-degree clockwise-rotated (outward-facing) unit-vectors of the edges defined by consecutive pairs of vertices starting with vertex 0.

Parameters

index Index of the normal to get.

Returns: Normal for the given index.

◆ GetNormals()

Span<const UnitVec2> box2d::PolygonShape::GetNormals ( ) const

inlinenoexcept

◆ GetVertex()

Length2D box2d::PolygonShape::GetVertex ( vertex_count_t index ) const

inline

Gets a vertex by index.

Vertices go counter-clockwise.

◆ GetVertexCount()

PolygonShape::vertex_count_t box2d::PolygonShape::GetVertexCount ( ) const

inlinenoexcept

Gets the vertex count.

Returns: value between 0 and MaxShapeVertices inclusive.

See also: MaxShapeVertices.

◆ GetVertices()

Span<const Length2D> box2d::PolygonShape::GetVertices ( ) const

inlinenoexcept

Gets the span of vertices.

Vertices go counter-clockwise.

◆ RayCast()

RayCastOutput PolygonShape::RayCast	(	const RayCastInput &	input,
		const Transformation &	xf,
		child_count_t	childIndex
	)		const

overridevirtualnoexcept

Cast a ray against a child shape.

Parameters

input	the ray-cast input parameters.
xf	the transform to be applied to the shape.
childIndex	the child shape index

Implements box2d::Shape.

◆ Set() [1/2]

void PolygonShape::Set ( Span< const Length2D > points )

noexcept

Creates a convex hull from the given array of local points. The size of the span must be in the range [1, MaxShapeVertices].

Warning: the points may be re-ordered, even if they form a convex polygon; collinear points are handled but not removed. Collinear points may lead to poor stacking behavior.

◆ Set() [2/2]

void PolygonShape::Set ( const VertexSet & points )

noexcept

Creates a convex hull from the given set of local points. The size of the set must be in the range [1, MaxShapeVertices].

Warning: the points may be re-ordered, even if they form a convex polygon; collinear points are handled but not removed. Collinear points may lead to poor stacking behavior.

◆ SetAsBox()

void PolygonShape::SetAsBox	(	Length	hx,
		Length	hy
	)

noexcept

Build vertices to represent an axis-aligned box centered on the local origin.

Parameters

hx	the half-width.
hy	the half-height.

◆ TestPoint()

bool PolygonShape::TestPoint	(	const Transformation &	xf,
		const Length2D	p
	)		const

overridevirtualnoexcept

Tests a point for containment in this shape.

Parameters

xf	the shape world transform.
p	a point in world coordinates.

Returns: true if point is contained in this shape, false otherwise.

Implements box2d::Shape.

◆ Transform()

void PolygonShape::Transform ( box2d::Transformation xf )

noexcept

Member Data Documentation

◆ InvalidVertex

constexpr auto box2d::PolygonShape::InvalidVertex = static_cast<vertex_count_t>(-1)

static

The documentation for this class was generated from the following files:

Classes

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Detailed Description

Member Typedef Documentation

◆ vertex_count_t

Constructor & Destructor Documentation

◆ PolygonShape() [1/4]

◆ PolygonShape() [2/4]

◆ PolygonShape() [3/4]

◆ PolygonShape() [4/4]

Member Function Documentation

◆ Accept()

◆ GetCentroid()

◆ GetChild()

◆ GetChildCount()

◆ GetDefaultConf()

◆ GetDefaultVertexRadius()

◆ GetMassData()

◆ GetNormal()

◆ GetNormals()

◆ GetVertex()

◆ GetVertexCount()

◆ GetVertices()

◆ RayCast()

◆ Set() [1/2]

◆ Set() [2/2]

◆ SetAsBox()

◆ TestPoint()

◆ Transform()

Member Data Documentation

◆ InvalidVertex