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  3. UClusterUnionComponent

UClusterUnionComponent

This does the bulk of the work exposing a physics cluster union to the game thread.

API > API/Runtime > API/Runtime/Engine > API/Runtime/Engine/PhysicsEngine

Inheritance Hierarchy

References

   
Module Engine
Header /Engine/Source/Runtime/Engine/Classes/PhysicsEngine/ClusterUnionComponent.h
Include #include "PhysicsEngine/ClusterUnionComponent.h"

Syntax

UCLASS (MinimalAPI)  
class UClusterUnionComponent : public UPrimitiveComponent

Remarks

This does the bulk of the work exposing a physics cluster union to the game thread. This component needs to be a primitive component primarily because of how physics proxies need to be registered with the solver with an association with a primitive component. This component can be used as part of AClusterUnionActor or on its own as its list of clustered components/actors can be specified dynamically at runtime and/or statically on asset creation.

The cluster union component needs to not only maintain a game thread representation of what's happening on the physics thread but it also needs to make sure this data gets replicated to every client. A general model of how the data flow happens is as follows:

[Server GT Command] -> [Server PT Command] -> [Server Modifies PT Data] -> [Server Sync PT Data back to GT Data].

This enables GT control over what happens to the cluster union BUT ALSO maintains a physics-first approach to the cluster union where a physics event can possibly cause the cluster union to break.

The GT data is replicated from the server to the clients either via the FClusterUnionReplicatedData on the cluster union component or per-child component data is replicated via the UClusterUnionReplicatedProxyComponent. Generally, the same flow is replicated on the client. The only exception is for replicating the X/R/V/W properties on the cluster union particle which does a GT -> PT data sync. There's no particula reason this happens...it just mirrors the single particle physics proxy here.

Variables

  Type Name Description
Public variable UProperty Category, EditAnywhere BlueprintReadWrite blueprintsetter bool bEnableDamageFromCollision Whether or not collisions against this geometry collection will apply strain which could cause the geometry collection to fracture.
Public variable FOnClusterUnionPostSyncBodies OnClusterUnionPostSyncBodiesEvent  
Public variable UProperty Category BlueprintAssignable FOnClusterUnionAddedComponent OnComponentAddedEvent  
Public variable FOnClusterUnionAddedComponentNative OnComponentAddedNativeEvent Native (fast, low overhead) versions
Public variable UProperty Category BlueprintAssignable FOnClusterUnionBoundsChanged OnComponentBoundsChangedEvent  
Public variable UProperty Category BlueprintAssignable FOnClusterUnionRemovedComponent OnComponentRemovedEvent  
Public variable FOnClusterUnionRemovedComponentNative OnComponentRemovedNativeEvent  
Protected variable TMap< TObjectKey< UPrimitiveComponent >, FClusteredComponentData > PerComponentData We need to keep track of the mapping of primitive components to physics objects.

Constructors

  Type Name Description
Public function  

UClusterUnionComponent ( const FObjectInitializer& ObjectInitializer
)

  

Functions

  Type Name Description
Public function UFunction BlueprintCallable, Category void

AddComponentToCluster ( UPrimitiveComponent* InComponent,
const TArray< int32 >& BoneIds,
bool bRebuildGeometry
)

  
Public function Static void  
Protected function void

BroadcastComponentAddedEvents ( UPrimitiveComponent* ChangedComponent,
const TArray< FClusterUnionBoneData >& BoneIds,
bool bIsNew,
const TArray< FClusterUnionBoneData >& RemovedBoneIDs
)

  
Protected function void

BroadcastComponentRemovedEvents ( UPrimitiveComponent* ChangedComponent,
const TArray< FClusterUnionBoneData >& InRemovedBonesData
)

  
Public function void

ChangeIfComponentBonesAreMainParticle ( UPrimitiveComponent* Component,
const TArray< int32 >& BoneIds,
bool bIsMain
)

  
Public function Const Chaos::FPhysicsObjectHandle This function will return information from the latest physics sync.
Public function void Force a rebuild of the GT geometry.
Public function UFunction void

ForceSetChildToParent ( UPrimitiveComponent* InComponent,
const TArray< int32 >& BoneIds,
const TArray< FTransform >& ChildToParent
)

 This should only be called on the client when replication happens.
Public function UFunction BlueprintCallable, Category TArray< AActor * >  
Public function Const TArray< int32 >  
Protected function Chaos::FClusterUnionPhysicsProxy *  
Protected function Const Chaos::FClusterUnionPhysicsProxy *  
Public function UFunction BlueprintCallable, Category TArray< UPrimitiveComponent * >  
Protected function Const const FClusterUnionReplicatedData &  
Public function Const const FSpatialAcceleration *  
Public function Const bool  
Protected function Const UFunction bool Whether or not this code is running on the server.
Public function UFunction bool  
Public function bool

LineTraceComponent ( TArray< FHitResult >& OutHit,
const FVector Start,
const FVector End,
ECollisionChannel TraceChannel,
const FCollisionQueryParams& Params,
const FCollisionResponseParams& ResponseParams,
const FCollisionObjectQueryParams& ObjectParams
)

 Multi-trace/sweep functions that only make sense in the context of a cluster union.
Public function Const int32  
Public function Virtual void

OnChildToParentUpdated ( UPrimitiveComponent* ChangedComponent,
const FLocalBonesToTransformMap& PerBoneChildToParent,
const FTransform& NewTransform,
TArray< TTuple< UPrimitiveComponent*, FTransform > >* OutNewComponents
)

  
Protected function Virtual UFunction void Handles changes to ReplicatedRigidState.
Public function UFunction BlueprintCallable, Category void

RemoveComponentBonesFromCluster ( UPrimitiveComponent* InComponent,
const TArray< int32 >& BoneIds
)

  
Public function UFunction BlueprintCallable, Category void  
Public function UFunction BlueprintCallable, Category void  
Public function Virtual UFunction BlueprintCallable, Category, Meta void

SetIsAnchored ( bool bIsAnchored
)

  
Protected function Virtual void

SetRigidState ( Chaos::EObjectStateType ObjectState
)

  
Public function bool

SweepComponent ( TArray< FHitResult >& OutHit,
const FVector Start,
const FVector End,
const FQuat& ShapeWorldRotation,
const FPhysicsGeometry& Geometry,
ECollisionChannel TraceChannel,
const FCollisionQueryParams& Params,
const FCollisionResponseParams& ResponseParams,
const FCollisionObjectQueryParams& ObjectParams
)

  
Public function void

SyncClusterUnionFromProxy ( const FTransform& NewTransform,
TArray< TTuple< UPrimitiveComponent*, FTransform > >* OutNewComponents
)

 SyncClusterUnionFromProxy will examine the make up of the cluster union (particles, child to parent, etc.) and do whatever is needed on the GT in terms of bookkeeping.
Public function Const void

VisitAllCurrentActors ( const TFunction< bool(AActor*)>& Lambda
)

  
Public function Const void Lambda returns whether or not iteration should continue;.

Overridden from UPrimitiveComponent

  Type Name Description
Public function Virtual bool Determines whether or not the simulate physics setting can be edited interactively on this component
Public function Virtual Const bool

ComponentOverlapComponentWithResultImpl ( const UPrimitiveComponent*const PrimComp,
const FVector& Pos,
const FQuat& Rot,
const FCollisionQueryParams& Params,
TArray< FOverlapResult >& OutOverlap
)

  
Public function Virtual Const FBodyInstance *

GetBodyInstance ( FName BoneName,
bool bGetWelded,
int32 Index
)

 Returns BodyInstance of the component.
Public function Virtual bool Returns if any body in this component is currently awake and simulating.
Public function Virtual bool

LineTraceComponent ( FHitResult& OutHit,
const FVector Start,
const FVector End,
ECollisionChannel TraceChannel,
const FCollisionQueryParams& Params,
const FCollisionResponseParams& ResponseParams,
const FCollisionObjectQueryParams& ObjectParams
)

 Trace a ray against just this component.
Public function Virtual bool

LineTraceComponent ( FHitResult& OutHit,
const FVector Start,
const FVector End,
const FCollisionQueryParams& Params
)

 Trace a ray against just this component.
Public function Virtual Const bool

OverlapComponentWithResult ( const FVector& Pos,
const FQuat& Rot,
const FPhysicsGeometry& Geometry,
ECollisionChannel TraceChannel,
const FCollisionQueryParams& Params,
const FCollisionResponseParams& ResponseParams,
const FCollisionObjectQueryParams& ObjectParams,
TArray< FOverlapResult >& OutOverlap
)

 Test the collision of the supplied shape at the supplied location, and determine if it overlaps this component.
Public function Virtual Const bool

OverlapComponentWithResult ( const FVector& Pos,
const FQuat& Rot,
const FCollisionShape& CollisionShape,
TArray< FOverlapResult >& OutOverlap
)

 Test the collision of the supplied shape at the supplied location, and determine if it overlaps this component.
Public function Virtual void

SetMassOverrideInKg ( FName BoneName,
float MassInKg,
bool bOverrideMass
)

 Set the cluster union total mass.
Public function Virtual void

SetSimulatePhysics ( bool bSimulate
)

 When this component is a simple/single body, this will enable or disable simulation on that body.
Public function Virtual Const bool Whether or not the primitive component should dispatch sleep/wake events.
Public function Virtual bool

SweepComponent ( FHitResult& OutHit,
const FVector Start,
const FVector End,
const FQuat& ShapeWorldRotation,
const FCollisionShape& CollisionShape,
bool bTraceComplex
)

 Trace a shape against just this component.
Public function Virtual bool

SweepComponent ( FHitResult& OutHit,
const FVector Start,
const FVector End,
const FQuat& ShapeWorldRotation,
const FPhysicsGeometry& Geometry,
ECollisionChannel TraceChannel,
const FCollisionQueryParams& Params,
const FCollisionResponseParams& ResponseParams,
const FCollisionObjectQueryParams& ObjectParams
)

 Trace a shape against just this component.
Public function Virtual void Ensure simulation is running for all bodies in this component.

Overridden from USceneComponent

  Type Name Description
Public function Virtual Const FBoxSphereBounds

CalcBounds ( const FTransform& LocalToWorld
)

 Calculate the bounds of the component. Default behavior is a bounding box/sphere of zero size.
Public function Virtual Const FVector Get velocity of the component: either ComponentVelocity, or the velocity of the physics body if simulating physics.
Public function Virtual void

OnReceiveReplicatedState ( const FVector X,
const FQuat R,
const FVector V,
const FVector W
)

 Called when client receive replication data, before replication is performed.
Public function Virtual void

OnUpdateTransform ( EUpdateTransformFlags UpdateTransformFlags,
ETeleportType Teleport
)

 Native callback when this component is moved

Overridden from UActorComponent

  Type Name Description
Public function Virtual Const bool Used to check that DestroyPhysicsState() is working correctly
Public function Virtual void Used to create any physics engine information for this component
Public function Virtual void Used to shut down and physics engine structure for this component
Public function Virtual Const bool Return true if CreatePhysicsState() should be called.

Overridden from UObject

  Type Name Description
Public function Virtual Const void Returns properties that are replicated for the lifetime of the actor channel

Overridden from INavRelevantInterface

  Type Name Description
Public function Virtual Const bool Collects custom navigable geometry of component.

Overridden from IPhysicsComponent

  Type Name Description
Public function Virtual Const TArray< Chaos::FPhysicsObject * >  
Public function Virtual Const Chaos::FPhysicsObjectId

GetIdFromGTParticle ( Chaos::FGeometryParticle* Particle
)

  
Public function Virtual Const Chaos::FPhysicsObject *

GetPhysicsObjectById ( Chaos::FPhysicsObjectId Id
)

  
Public function Virtual Const Chaos::FPhysicsObject *

GetPhysicsObjectByName ( const FName& Name
)

  

Classes

  Type Name Description
Public struct FMappedBoneData    
Public struct FMappedComponentKey Structure that stores an object key and its raw ptr, so it can be accessed without going trough the global uobjects array (so it could be garbage, therefore it has to be used withing the same frame)  

Typedefs

Name Description
FLocalBonesToTransformMap There are several instances where we have 1 single elements. The inline allocator should help in these cases without a huge impact when we go over.
FSpatialAcceleration  

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