A collision response oriented description of the intersection of two convex shapes. More...

#include <Manifold.hpp>

Collaboration diagram for playrho::d2::Manifold:

Classes
struct	Conf
	Configuration data for manifold calculation. More...

struct	Point
	Data for a point of collision in a Manifold. More...

struct	PointArray
	Point array structure. More...

Public Types
enum	Type : std::uint8_t { e_unset, e_circles, e_faceA, e_faceB }
	Manifold type. More...

using	size_type = std::remove_const< decltype(MaxManifoldPoints)>::type
	Size type.

using	CfIndex = ContactFeature::Index
	Contact feature index.

using	CfType = ContactFeature::Type
	Contact feature type.

Public Member Functions
	Manifold ()=default
	Default constructor. More...

	Manifold (const Manifold &copy)=default
	Copy constructor.

constexpr Type	GetType () const noexcept
	Gets the type of this manifold. More...

constexpr size_type	GetPointCount () const noexcept
	Gets the manifold point count. More...

constexpr ContactFeature	GetContactFeature (size_type index) const noexcept
	Gets the contact feature for the given index.

constexpr Momentum2	GetContactImpulses (size_type index) const noexcept
	Gets the contact impulses for the given index. More...

void	SetContactImpulses (size_type index, Momentum2 value) noexcept
	Sets the contact impulses for the given index. More...

const Point &	GetPoint (size_type index) const noexcept
	Gets the point identified by the given index.

void	SetPointImpulses (size_type index, Momentum n, Momentum t)
	Sets the point impulses for the given index.

void	AddPoint (const Point &mp) noexcept
	Adds a new point. More...

void	AddPoint (CfType type, CfIndex index, Length2 point) noexcept
	Adds a new point with the given data.

constexpr UnitVec	GetLocalNormal () const noexcept
	Gets the local normal for a face-type manifold. More...

constexpr Length2	GetLocalPoint () const noexcept
	Gets the local point. More...

constexpr Length2	GetOpposingPoint (size_type index) const noexcept
	Gets the opposing point.

Static Public Member Functions
static Manifold	GetForCircles (Length2 vA, CfIndex iA, Length2 vB, CfIndex iB) noexcept
	Gets a circles-typed manifold with one point. More...

static Manifold	GetForFaceA (UnitVec normalA, Length2 faceA) noexcept
	Gets a face A typed manifold. More...

static Manifold	GetForFaceA (UnitVec ln, Length2 lp, const Point &mp1) noexcept
	Gets a face A typed manifold. More...

static Manifold	GetForFaceA (UnitVec ln, Length2 lp, const Point &mp1, const Point &mp2) noexcept
	Gets a face A typed manifold. More...

static Manifold	GetForFaceB (UnitVec ln, Length2 lp) noexcept
	Gets a face B typed manifold. More...

static Manifold	GetForFaceB (UnitVec ln, Length2 lp, const Point &mp1) noexcept
	Gets a face B typed manifold. More...

static Manifold	GetForFaceB (UnitVec ln, Length2 lp, const Point &mp1, const Point &mp2) noexcept
	Gets a face B typed manifold. More...

static Manifold	GetForFaceA (UnitVec na, CfIndex ia, Length2 pa) noexcept
	Gets the face A manifold for the given data.

static Manifold	GetForFaceB (UnitVec nb, CfIndex ib, Length2 pb) noexcept
	Gets the face B manifold for the given data.

static Manifold	GetForFaceA (UnitVec na, CfIndex ia, Length2 pa, CfType tb0, CfIndex ib0, Length2 pb0) noexcept
	Gets the face A manifold for the given data.

static Manifold	GetForFaceB (UnitVec nb, CfIndex ib, Length2 pb, CfType ta0, CfIndex ia0, Length2 pa0) noexcept
	Gets the face B manifold for the given data.

static Manifold	GetForFaceA (UnitVec na, CfIndex ia, Length2 pa, CfType tb0, CfIndex ib0, Length2 pb0, CfType tb1, CfIndex ib1, Length2 pb1) noexcept
	Gets the face A manifold for the given data.

static Manifold	GetForFaceB (UnitVec nb, CfIndex ib, Length2 pb, CfType ta0, CfIndex ia0, Length2 pa0, CfType ta1, CfIndex ia1, Length2 pa1) noexcept
	Gets the face B manifold for the given data.

Private Member Functions
constexpr	Manifold (Type t, UnitVec ln, Length2 lp, size_type n, const PointArray &mpa) noexcept
	Constructs manifold with array of points using the given values. More...

Private Attributes
Type	m_type = e_unset
	Type of collision this manifold is associated with (1-byte).

size_type	m_pointCount = 0
	Number of defined manifold points (1-byte).

UnitVec	m_localNormal = GetInvalid<decltype(m_localNormal)>()
	Local normal. More...

Length2	m_localPoint = GetInvalid<Length2>()
	Local point. More...

PointArray	m_points
	Points of contact (at least 40-bytes). More...

Related Functions
(Note that these are not member functions.)
bool	operator== (const Manifold &lhs, const Manifold &rhs) noexcept
	Manifold equality operator. More...

bool	operator!= (const Manifold &lhs, const Manifold &rhs) noexcept
	Manifold inequality operator. More...

Manifold	CollideShapes (const DistanceProxy &shapeA, const Transformation &xfA, const DistanceProxy &shapeB, const Transformation &xfB, Manifold::Conf conf=GetDefaultManifoldConf())
	Calculates the relevant collision manifold. More...

template<>
constexpr bool	IsValid (const d2::Manifold &value) noexcept
	Gets whether the given manifold is valid.

WorldManifold	GetWorldManifold (const Manifold &manifold, Transformation xfA, Length radiusA, Transformation xfB, Length radiusB)
	Gets the world manifold for the given data. More...

Detailed Description

A collision response oriented description of the intersection of two convex shapes.

This describes zero, one, or two points of contact for which impulses should be applied to most naturally resolve those contacts. Ideally the manifold is calculated at the earliest point in time of contact occurring. The further past that time, the less natural contact resolution of solid bodies will be - eventually resulting in oddities like tunneling.

Multiple types of contact are supported: clip point versus plane with radius, point versus point with radius (circles). Contacts are stored 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.

Conceptually, a manifold represents the intersection of two convex sets (which is itself a convex set) and a solution for moving the sets away from each other to eliminate the intersection.

Note: The local point and local normal usage depends on the manifold type. For details, see the documentation associated with the different manifold types.; Every point adds computational overhead to the collision response calculation - so express collision manifolds with one point if possible instead of two.

See also: Contact, PositionConstraint, VelocityConstraint; https://en.wikipedia.org/wiki/Convex_set; http://box2d.org/files/GDC2007/GDC2007_Catto_Erin_Physics2.ppt

Examples: World.cpp.

Member Enumeration Documentation

◆ Type

enum playrho::d2::Manifold::Type : std::uint8_t

Manifold type.

Note: This is by design a 1-byte sized type.

Enumerator
e_unset	Unset type. Manifold is unset. For manifolds of this type: the point count is zero, point data is undefined, and all other properties are invalid.
e_circles	Circles type. Manifold is for circle-to-circle like collisions. Note For manifolds of this type: the local point is local center of "circle-A" (where shape A wasn't necessarily a circle but treating it as such is useful), the local normal is invalid (and unused) and, the point count will be zero or one where the contact feature will be `ContactFeature{e_vertex, i, e_vertex, j}` where i and j are indexes of the vertexes of shapes A and B respectively.
e_faceA	Face-A type. Indicates: local point is center of face A, local normal is normal on shape A, and the local points of Point instances are the local center of circle B or a clip point of polygon B where the contact feature will be `ContactFeature{e_face, i, e_vertex, j}` or `ContactFeature{e_face, i, e_face, j} where i and j are indexes for the vertex or edge of shapes A and B respectively.`.
e_faceB	Face-B type. Indicates: local point is center of face B, local normal is normal on shape B, and the local points of Point instances are the local center of circle A or a clip point of polygon A where the contact feature will be `ContactFeature{e_face, i, e_vertex, j}` or `ContactFeature{e_face, i, e_face, j} where i and j are indexes for the vertex or edge of shapes A and B respectively.`.

Constructor & Destructor Documentation

◆ Manifold() [1/2]

playrho::d2::Manifold::Manifold ( )

default

Default constructor.

Constructs an unset-type manifold. For an unset-type manifold: point count is zero, point data is undefined, and all other properties are invalid.

◆ Manifold() [2/2]

constexpr playrho::d2::Manifold::Manifold	(	Type	t,
		UnitVec	ln,
		Length2	lp,
		size_type	n,
		const PointArray &	mpa
	)

constexprprivatenoexcept

Constructs manifold with array of points using the given values.

Parameters

t	Manifold type.
ln	Local normal.
lp	Local point.
n	number of points defined in array.
mpa	Manifold point array.

Member Function Documentation

◆ AddPoint()

void playrho::d2::Manifold::AddPoint ( const Point & mp )

inlinenoexcept

Adds a new point.

This can be called once for circle type manifolds, and up to twice for face-A or face-B type manifolds. GetPointCount() can be called to find out how many points have already been added.

Warning: Behavior is undefined if this object's type is e_unset.; Behavior is undefined if this is called more than twice.

◆ GetContactImpulses()

constexpr Momentum2 playrho::d2::Manifold::GetContactImpulses ( size_type index ) const

inlineconstexprnoexcept

Gets the contact impulses for the given index.

Returns: Pair of impulses where the first impulse is the "normal impulse" and the second impulse is the "tangent impulse".

◆ GetForCircles()

static Manifold playrho::d2::Manifold::GetForCircles	(	Length2	vA,
		CfIndex	iA,
		Length2	vB,
		CfIndex	iB
	)

inlinestaticnoexcept

Gets a circles-typed manifold with one point.

Parameters

vA	Local center of "circle" A.
iA	Index of vertex from shape A representing the local center of "circle" A.
vB	Local center of "circle" B.
iB	Index of vertex from shape B representing the local center of "circle" B.

Referenced by playrho::d2::GetManifold().

◆ GetForFaceA() [1/3]

static Manifold playrho::d2::Manifold::GetForFaceA	(	UnitVec	ln,
		Length2	lp,
		const Point &	mp1
	)

inlinestaticnoexcept

Gets a face A typed manifold.

Parameters

ln	Normal on polygon A.
lp	Center of face A.
mp1	Manifold point 1 (of 1).

◆ GetForFaceA() [2/3]

static Manifold playrho::d2::Manifold::GetForFaceA	(	UnitVec	ln,
		Length2	lp,
		const Point &	mp1,
		const Point &	mp2
	)

inlinestaticnoexcept

Gets a face A typed manifold.

Parameters

ln	Normal on polygon A.
lp	Center of face A.
mp1	Manifold point 1 (of 2).
mp2	Manifold point 2 (of 2).

◆ GetForFaceA() [3/3]

static Manifold playrho::d2::Manifold::GetForFaceA	(	UnitVec	normalA,
		Length2	faceA
	)

inlinestaticnoexcept

Gets a face A typed manifold.

Parameters

normalA	Local normal of the face from polygon A.
faceA	Any point in local coordinates on the face whose normal was provided.

Referenced by playrho::d2::GetManifold().

◆ GetForFaceB() [1/3]

static Manifold playrho::d2::Manifold::GetForFaceB	(	UnitVec	ln,
		Length2	lp
	)

inlinestaticnoexcept

Gets a face B typed manifold.

Parameters

ln	Normal on polygon B.
lp	Center of face B.

Referenced by playrho::d2::GetManifold().

◆ GetForFaceB() [2/3]

static Manifold playrho::d2::Manifold::GetForFaceB	(	UnitVec	ln,
		Length2	lp,
		const Point &	mp1
	)

inlinestaticnoexcept

Gets a face B typed manifold.

Parameters

ln	Normal on polygon B.
lp	Center of face B.
mp1	Manifold point 1.

◆ GetForFaceB() [3/3]

static Manifold playrho::d2::Manifold::GetForFaceB	(	UnitVec	ln,
		Length2	lp,
		const Point &	mp1,
		const Point &	mp2
	)

inlinestaticnoexcept

Gets a face B typed manifold.

Parameters

ln	Normal on polygon B.
lp	Center of face B.
mp1	Manifold point 1 (of 2).
mp2	Manifold point 2 (of 2).

◆ GetLocalNormal()

constexpr UnitVec playrho::d2::Manifold::GetLocalNormal ( ) const

inlineconstexprnoexcept

Gets the local normal for a face-type manifold.

Note: Only valid for face-A or face-B type manifolds.

Warning: Behavior is undefined for unset (e_unset) type manifolds.; Behavior is undefined for circles (e_circles) type manifolds.

Returns: Local normal if the manifold type is face A or face B, else invalid value.

Referenced by playrho::d2::GetPSM().

◆ GetLocalPoint()

constexpr Length2 playrho::d2::Manifold::GetLocalPoint ( ) const

inlineconstexprnoexcept

Gets the local point.

This is the: local center of "circle" A for circles-type manifolds; the center of face A for face-A-type manifolds; or the center of face B for face-B-type manifolds.

Note: Only valid for circle, face-A, or face-B type manifolds.

Warning: Behavior is undefined for unset (e_unset) type manifolds.

Returns: Local point.

Examples: World.cpp.

Referenced by playrho::d2::GetPSM().

◆ GetPointCount()

constexpr size_type playrho::d2::Manifold::GetPointCount ( ) const

inlineconstexprnoexcept

Gets the manifold point count.

This is the count of contact points for this manifold. Only up to this many points can be validly accessed using the GetPoint() method.

Note: Non-zero values indicate that the two shapes are touching.

Returns: Value between 0 and MaxManifoldPoints.

See also: MaxManifoldPoints.; AddPoint().; GetPoint().

Examples: World.cpp.

◆ GetType()

constexpr Type playrho::d2::Manifold::GetType ( ) const

inlineconstexprnoexcept

Gets the type of this manifold.

Note: This must be a constant expression in order to use it in the context of the IsValid specialized template function for it.

Examples: World.cpp.

Referenced by playrho::d2::GetPSM(), playrho::d2::GetWorldManifold(), and playrho::IsValid().

◆ SetContactImpulses()

void playrho::d2::Manifold::SetContactImpulses	(	size_type	index,
		Momentum2	value
	)

inlinenoexcept

Sets the contact impulses for the given index.

Sets the contact impulses for the given index where the first impulse is the "normal impulse" and the second impulse is the "tangent impulse".

Friends And Related Function Documentation

◆ CollideShapes()

Manifold CollideShapes	(	const DistanceProxy &	shapeA,
		const Transformation &	xfA,
		const DistanceProxy &	shapeB,
		const Transformation &	xfB,
		Manifold::Conf	conf = `GetDefaultManifoldConf()`
	)

Note: The returned touching state information typically agrees with that returned from the distance-proxy-based TestOverlap function. This is not always the case however especially when the separation or overlap distance is closer to zero.

◆ GetWorldManifold()

WorldManifold GetWorldManifold	(	const Manifold &	manifold,
		Transformation	xfA,
		Length	radiusA,
		Transformation	xfB,
		Length	radiusB
	)

Precondition: The given manifold input has between 0 and 2 points.

Parameters

manifold	Manifold to use. Uses the manifold's type, local point, local normal, point-count, and the indexed-points' local point data.
xfA	Transformation A.
radiusA	Radius of shape A.
xfB	Transformation B.
radiusB	Radius of shape B.

Returns: World manifold value for the given inputs which will have the same number of points as the given manifold has. The returned world manifold points will be the mid-points of the manifold intersection.

◆ operator!=()

bool operator!=	(	const Manifold &	lhs,
		const Manifold &	rhs
	)

Determines whether the two given manifolds are not equal.

◆ operator==()

bool operator==	(	const Manifold &	lhs,
		const Manifold &	rhs
	)

Note: In-so-far as manifold points are concerned, order doesn't matter; only whether the two manifolds have the same point set.

Member Data Documentation

◆ m_localNormal

UnitVec playrho::d2::Manifold::m_localNormal = GetInvalid<decltype(m_localNormal)>()

private

Local normal.

Exact usage depends on manifold type (8-bytes).

Note: Invalid for the unset and circle manifold types.

Referenced by GetLocalNormal().

◆ m_localPoint

Length2 playrho::d2::Manifold::m_localPoint = GetInvalid<Length2>()

private

Local point.

Exact usage depends on manifold type (8-bytes).

Note: Invalid for the unset manifold type.

Referenced by GetLocalPoint().

◆ m_points

PointArray playrho::d2::Manifold::m_points

private

Points of contact (at least 40-bytes).

See also: pointCount.

Referenced by GetContactFeature(), GetContactImpulses(), GetOpposingPoint(), GetPoint(), SetContactImpulses(), and SetPointImpulses().

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

Manifold.hpp
WorldManifold.hpp

Classes

Public Types

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Related Functions

Detailed Description

Member Enumeration Documentation

◆ Type

Constructor & Destructor Documentation

◆ Manifold() [1/2]

◆ Manifold() [2/2]

Member Function Documentation

◆ AddPoint()

◆ GetContactImpulses()

◆ GetForCircles()

◆ GetForFaceA() [1/3]

◆ GetForFaceA() [2/3]

◆ GetForFaceA() [3/3]

◆ GetForFaceB() [1/3]

◆ GetForFaceB() [2/3]

◆ GetForFaceB() [3/3]

◆ GetLocalNormal()

◆ GetLocalPoint()

◆ GetPointCount()

◆ GetType()

◆ SetContactImpulses()

Friends And Related Function Documentation

◆ CollideShapes()

◆ GetWorldManifold()

◆ operator!=()

◆ operator==()

Member Data Documentation

◆ m_localNormal

◆ m_localPoint

◆ m_points