An allocator and container of collision constraints that supports reuse of constraints from the previous tick. More...

#include <CollisionConstraintAllocator.h>

Public Member Functions
	UE_NONCOPYABLE (FCollisionConstraintAllocator)

	FCollisionConstraintAllocator (const int32 InNumCollisionsPerBlock=1000)

	~FCollisionConstraintAllocator ()

void	SetCollisionContainer (FPBDCollisionConstraints *InCollisionContainer)

void	SetMaxContexts (const int32 MaxContexts)

FCollisionContextAllocator *	GetContextAllocator (const int32 Index)

TArrayView< FPBDCollisionConstraint *const >	GetConstraints () const
	The set of collision constraints for the current tick (created or reinstated)

TArrayView< FPBDCollisionConstraint *const >	GetCCDConstraints () const
	The set of sweep collision constraints for the current tick (created or reinstated)

TArrayView< const FPBDCollisionConstraint *const >	GetConstConstraints () const
	The set of collision constraints for the current tick (created or reinstated)

int32	GetCurrentEpoch () const

bool	IsConstraintExpired (const FPBDCollisionConstraint &Constraint)

void	Reset ()
	Destroy all constraints.

void	BeginFrame ()
	Called at the start of the frame to clear the frame's active collision list.

void	BeginDetectCollisions ()
	Called at the start of the tick to prepare for collision detection. Resets the list of active contacts.

CHAOS_API void	EndDetectCollisions ()
	Called after collision detection to clean up Prunes unused contacts.

void	PruneExpiredItems ()
	Called each tick after the graph is updated to remove unused collisions.

CHAOS_API void	ProcessNewMidPhases ()

void	ProcessInjectedConstraints ()
	If we add new constraints after collision detection, do what needs to be done to add them to the system.

void	AddActiveConstraint (FPBDCollisionConstraint *Constraint)

void	AddResimConstraints (const TArray< FPBDCollisionConstraint > &InConstraints, const FCollisionContext Context)
	Add a set of pre-built constraints and build required internal mapping data This is used by the resim cache when restoring constraints after a desync.

void	SortConstraintsHandles ()
	Sort all the constraints for better solver stability.

CHAOS_API void	RemoveParticle (FGeometryParticleHandle *Particle)
	Destroy all collision and caches involving the particle Called when a particle is destroyed or disabled (not sleeping).

template<typename TLambda >
void	VisitConstCollisions (const TLambda &Visitor, const ECollisionVisitorFlags &VisitFlags=ECollisionVisitorFlags::VisitDefault) const
	Iterate over all collisions (read-only), including sleeping ones Visitor signature: ECollisionVisitorResult(const FPBDCollisionConstraint&)

template<typename TLambda >
void	VisitCollisions (const TLambda &Visitor) const
	Iterate over all collisions (write-enabled), including sleeping ones Visitor signature: ECollisionVisitorResult(FPBDCollisionConstraint&)

template<typename TLambda >
void	VisitMidPhases (const TLambda &Visitor)
	Iterate over all midphases Visitor signature: ECollisionVisitorResult(FParticlePairMidPhase&)

void	SetIsDeterministic (const bool bInIsDeterministic)

Friends
class	FCollisionContextAllocator

Detailed Description

An allocator and container of collision constraints that supports reuse of constraints from the previous tick.

All constraint pointers are persistent in memory until Destroy() is called, or until they are pruned.

This allocator maintains the set of all overlapping particle pairs, with each overlapping particle pair managed by a FParticlePairMidPhase object. the MidPhase object is what actually calls the Narrow Phase and maintains the set of collision constraints for all the shape pairs on the particles.

Constraints are allocated during the collision detection phase and retained between ticks. An attempt to create a constraint for the same shape pair as seen on the previous tick will return the existing collision constraint with all of its data intact.

The allocator also keeps a list of Standard and Swept collision constraints that are active for the current tick. This list gets reset and rebuilt every frame during collision detection. It may get added to by the IslandManager if some islands are woken following collision detection.

The allocators Epoch counter is used to determine whether a constraint (or midphase object) generated any contacts for the current frame. When a midphase creates or updates a constraint, it copies the current Epoch counter.

The Midphase list is pruned at the end of each tick so if particles are destroyed or a particle pair is no longer overlapping, the collisions will be destroyed.

When particles are destroyed, we do not immediately destroy the MidPhases (or Collisions) that are associoated with the particle. Instead, we clear the particle pointer from them, but leave their destruction to the pruning process. This avoids the need to parse collision and midphase lists whenever a particle is disabled.

NOTE: To reduce RBAN memory use, we do not create any collision blocks until the first call to CreateCollisionConstraint (see ConstraintPool initialization)

Constructor & Destructor Documentation

◆ FCollisionConstraintAllocator()

Chaos::Private::FCollisionConstraintAllocator::FCollisionConstraintAllocator ( const int32 InNumCollisionsPerBlock = 1000 )

inline

◆ ~FCollisionConstraintAllocator()

Chaos::Private::FCollisionConstraintAllocator::~FCollisionConstraintAllocator ( )

inline

Member Function Documentation

◆ AddActiveConstraint()

void Chaos::Private::FCollisionConstraintAllocator::AddActiveConstraint ( FPBDCollisionConstraint * Constraint )

This should be called when a sleeping constraint is activated after the narrow phase, typically in the island manager. This is mainly so that any systems asking for a list of active constraints are provided all constraints that may have contributed to the simulation, including those that were added when an island is awoken.

◆ AddResimConstraints()

void Chaos::Private::FCollisionConstraintAllocator::AddResimConstraints	(	const TArray< FPBDCollisionConstraint > &	InConstraints,
		const FCollisionContext	Context
	)

inline

Add a set of pre-built constraints and build required internal mapping data This is used by the resim cache when restoring constraints after a desync.

◆ BeginDetectCollisions()

void Chaos::Private::FCollisionConstraintAllocator::BeginDetectCollisions ( )

inline

Called at the start of the tick to prepare for collision detection. Resets the list of active contacts.

◆ BeginFrame()

void Chaos::Private::FCollisionConstraintAllocator::BeginFrame ( )

inline

Called at the start of the frame to clear the frame's active collision list.

◆ EndDetectCollisions()

void Chaos::Private::FCollisionConstraintAllocator::EndDetectCollisions ( )

Called after collision detection to clean up Prunes unused contacts.

◆ GetCCDConstraints()

TArrayView< FPBDCollisionConstraint *const > Chaos::Private::FCollisionConstraintAllocator::GetCCDConstraints ( ) const

inline

The set of sweep collision constraints for the current tick (created or reinstated)

Note: Some elements may be null (constraints that have been explicitly deleted); This is not thread-safe and should not be used during the collision detection phase (i.e., when the list is being built)

◆ GetConstConstraints()

TArrayView< const FPBDCollisionConstraint *const > Chaos::Private::FCollisionConstraintAllocator::GetConstConstraints ( ) const

inline

The set of collision constraints for the current tick (created or reinstated)

Note: Some elements may be null (constraints that have been explicitly deleted); This is not thread-safe and should not be used during the collision detection phase (i.e., when the list is being built)

◆ GetConstraints()

TArrayView< FPBDCollisionConstraint *const > Chaos::Private::FCollisionConstraintAllocator::GetConstraints ( ) const

inline

The set of collision constraints for the current tick (created or reinstated)

Note: Some elements may be null (constraints that have been deleted); This is not thread-safe and should not be used during the collision detection phase (i.e., when the list is being built)

◆ GetContextAllocator()

FCollisionContextAllocator * Chaos::Private::FCollisionConstraintAllocator::GetContextAllocator ( const int32 Index )

inline

◆ GetCurrentEpoch()

int32 Chaos::Private::FCollisionConstraintAllocator::GetCurrentEpoch ( ) const

inline

◆ IsConstraintExpired()

bool Chaos::Private::FCollisionConstraintAllocator::IsConstraintExpired ( const FPBDCollisionConstraint & Constraint )

inline

Has the constraint expired. An expired constraint is one that was not refreshed this tick.

Note: Sleeping constrainst will report they are expired, but they should not be deleted until awoken. We deliberately don't check the sleeping flag here because it adds a cache miss. This function should be called only when you already know the sleep state (or you must also check IsSleeping())

◆ ProcessInjectedConstraints()

void Chaos::Private::FCollisionConstraintAllocator::ProcessInjectedConstraints ( )

inline

If we add new constraints after collision detection, do what needs to be done to add them to the system.

◆ ProcessNewMidPhases()

void Chaos::Private::FCollisionConstraintAllocator::ProcessNewMidPhases ( )

Collect all the midphases created on the context allocators (probably on multiple threads) and register them

◆ PruneExpiredItems()

void Chaos::Private::FCollisionConstraintAllocator::PruneExpiredItems ( )

inline

Called each tick after the graph is updated to remove unused collisions.

◆ RemoveParticle()

void Chaos::Private::FCollisionConstraintAllocator::RemoveParticle ( FGeometryParticleHandle * Particle )

Destroy all collision and caches involving the particle Called when a particle is destroyed or disabled (not sleeping).

◆ Reset()

void Chaos::Private::FCollisionConstraintAllocator::Reset ( )

inline

Destroy all constraints.

◆ SetCollisionContainer()

void Chaos::Private::FCollisionConstraintAllocator::SetCollisionContainer ( FPBDCollisionConstraints * InCollisionContainer )

inline

◆ SetIsDeterministic()

void Chaos::Private::FCollisionConstraintAllocator::SetIsDeterministic ( const bool bInIsDeterministic )

inline

Enable/Disable determinism (extra sorting steps after collision detection)

◆ SetMaxContexts()

void Chaos::Private::FCollisionConstraintAllocator::SetMaxContexts ( const int32 MaxContexts )

inline

◆ SortConstraintsHandles()

void Chaos::Private::FCollisionConstraintAllocator::SortConstraintsHandles ( )

inline

Sort all the constraints for better solver stability.

◆ UE_NONCOPYABLE()

Chaos::Private::FCollisionConstraintAllocator::UE_NONCOPYABLE ( FCollisionConstraintAllocator )

◆ VisitCollisions()

template<typename TLambda >

void Chaos::Private::FCollisionConstraintAllocator::VisitCollisions ( const TLambda & Visitor ) const

inline

Iterate over all collisions (write-enabled), including sleeping ones Visitor signature: ECollisionVisitorResult(FPBDCollisionConstraint&)

◆ VisitConstCollisions()

template<typename TLambda >

void Chaos::Private::FCollisionConstraintAllocator::VisitConstCollisions	(	const TLambda &	Visitor,
		const ECollisionVisitorFlags &	VisitFlags = `ECollisionVisitorFlags::VisitDefault`
	)		const

inline

Iterate over all collisions (read-only), including sleeping ones Visitor signature: ECollisionVisitorResult(const FPBDCollisionConstraint&)

◆ VisitMidPhases()

template<typename TLambda >

void Chaos::Private::FCollisionConstraintAllocator::VisitMidPhases ( const TLambda & Visitor )

inline

Iterate over all midphases Visitor signature: ECollisionVisitorResult(FParticlePairMidPhase&)

Friends And Related Symbol Documentation

◆ FCollisionContextAllocator

friend class FCollisionContextAllocator

friend

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

Engine/Source/Runtime/Experimental/Chaos/Public/Chaos/Collision/CollisionConstraintAllocator.h
Engine/Source/Runtime/Experimental/Chaos/Private/Chaos/Collision/CollisionConstraintAllocator.cpp

Public Member Functions

Friends

Detailed Description

Constructor & Destructor Documentation

◆ FCollisionConstraintAllocator()

◆ ~FCollisionConstraintAllocator()

Member Function Documentation

◆ AddActiveConstraint()

◆ AddResimConstraints()

◆ BeginDetectCollisions()

◆ BeginFrame()

◆ EndDetectCollisions()

◆ GetCCDConstraints()

◆ GetConstConstraints()

◆ GetConstraints()

◆ GetContextAllocator()

◆ GetCurrentEpoch()

◆ IsConstraintExpired()

◆ ProcessInjectedConstraints()

◆ ProcessNewMidPhases()

◆ PruneExpiredItems()

◆ RemoveParticle()

◆ Reset()

◆ SetCollisionContainer()

◆ SetIsDeterministic()

◆ SetMaxContexts()

◆ SortConstraintsHandles()

◆ UE_NONCOPYABLE()

◆ VisitCollisions()

◆ VisitConstCollisions()

◆ VisitMidPhases()

Friends And Related Symbol Documentation

◆ FCollisionContextAllocator