Scene index that resolves velocity-based motion for all prims that support it. More...

#include <velocityMotionResolvingSceneIndex.h>

Inheritance diagram for HdsiVelocityMotionResolvingSceneIndex:

Public Member Functions
HDSI_API HdSceneIndexPrim	GetPrim (const SdfPath &primPath) const override
	Returns a pair of (prim type, datasource).

HDSI_API SdfPathVector	GetChildPrimPaths (const SdfPath &primPath) const override
	Returns the paths of all scene index prims located immediately below primPath.

Public Member Functions inherited from HdSingleInputFilteringSceneIndexBase
HD_API std::vector< HdSceneIndexBaseRefPtr >	GetInputScenes () const final

virtual std::vector< HdSceneIndexBaseRefPtr >	GetInputScenes () const =0

Public Member Functions inherited from HdSceneIndexBase
HD_API void	AddObserver (const HdSceneIndexObserverPtr &observer)
	Adds an observer to this scene index.

HD_API void	RemoveObserver (const HdSceneIndexObserverPtr &observer)
	Removes an observer from this scene index; the given observer will no longer be forwarded notices.

virtual HdSceneIndexPrim	GetPrim (const SdfPath &primPath) const =0
	Returns a pair of (prim type, datasource).

virtual SdfPathVector	GetChildPrimPaths (const SdfPath &primPath) const =0
	Returns the paths of all scene index prims located immediately below primPath.

HdDataSourceBaseHandle	GetDataSource (const SdfPath &primPath, const HdDataSourceLocator &locator) const
	A convenience function: look up the object at primPath, and if successful return the datasource at locator within that prim.

HD_API void	SystemMessage (const TfToken &messageType, const HdDataSourceBaseHandle &args)
	Sends a message with optional arguments to this and any upstream input scene indices.

HD_API std::string	GetDisplayName () const
	Returns a value previously set by SetDisplayName.

HD_API void	SetDisplayName (const std::string &n)
	Allows for scene index instances to be identified in a more contextually relevant way.

HD_API void	AddTag (const TfToken &tag)
	Adds a specified tag token to a scene index instance.

HD_API void	RemoveTag (const TfToken &tag)
	Removes a specified tag token to a scene index instance.

HD_API bool	HasTag (const TfToken &tag) const
	Returns true if a specified tag token has been added to a scene index instance.

HD_API TfTokenVector	GetTags () const
	Returns all tag tokens currently added to a scene index instance.

Public Member Functions inherited from TfRefBase
	TfRefBase (TfRefBase const &)

TfRefBase &	operator= (TfRefBase const &)

size_t	GetCurrentCount () const
	Return the current reference count of this object.

bool	IsUnique () const
	Return true if only one `TfRefPtr` points to this object.

void	SetShouldInvokeUniqueChangedListener (bool shouldCall)

Public Member Functions inherited from TfWeakBase
	TfWeakBase (const TfWeakBase &)

const TfWeakBase &	__GetTfWeakBase__ () const

const TfWeakBase &	operator= (const TfWeakBase &)

void	EnableNotification2 () const

TF_API void const *	GetUniqueIdentifier () const

Static Public Member Functions
static HDSI_API HdsiVelocityMotionResolvingSceneIndexRefPtr	New (const HdSceneIndexBaseRefPtr &inputSceneIndex, const HdContainerDataSourceHandle &inputArgs=nullptr)

static HDSI_API bool	PrimTypeSupportsVelocityMotion (const TfToken &primType)

Static Public Member Functions inherited from TfRefBase
static TF_API void	SetUniqueChangedListener (UniqueChangedListener listener)

Protected Member Functions
	HdsiVelocityMotionResolvingSceneIndex (const HdSceneIndexBaseRefPtr &inputSceneIndex, const HdContainerDataSourceHandle &inputArgs=nullptr)

void	_PrimsAdded (const HdSceneIndexBase &sender, const HdSceneIndexObserver::AddedPrimEntries &entries) override

void	_PrimsRemoved (const HdSceneIndexBase &sender, const HdSceneIndexObserver::RemovedPrimEntries &entries) override

void	_PrimsDirtied (const HdSceneIndexBase &sender, const HdSceneIndexObserver::DirtiedPrimEntries &entries) override

Protected Member Functions inherited from HdSingleInputFilteringSceneIndexBase
HD_API	HdSingleInputFilteringSceneIndexBase (const HdSceneIndexBaseRefPtr &inputSceneIndex)

virtual void	_PrimsAdded (const HdSceneIndexBase &sender, const HdSceneIndexObserver::AddedPrimEntries &entries)=0

virtual void	_PrimsRemoved (const HdSceneIndexBase &sender, const HdSceneIndexObserver::RemovedPrimEntries &entries)=0

virtual void	_PrimsDirtied (const HdSceneIndexBase &sender, const HdSceneIndexObserver::DirtiedPrimEntries &entries)=0

virtual HD_API void	_PrimsRenamed (const HdSceneIndexBase &sender, const HdSceneIndexObserver::RenamedPrimEntries &entries)

const HdSceneIndexBaseRefPtr &	_GetInputSceneIndex () const
	Returns the input scene.

Protected Member Functions inherited from HdSceneIndexBase
HD_API void	_SendPrimsAdded (const HdSceneIndexObserver::AddedPrimEntries &entries)
	Notify attached observers of prims added to the scene.

HD_API void	_SendPrimsRemoved (const HdSceneIndexObserver::RemovedPrimEntries &entries)
	Notify attached observers of prims removed from the scene.

HD_API void	_SendPrimsDirtied (const HdSceneIndexObserver::DirtiedPrimEntries &entries)
	Notify attached observers of datasource invalidations from the scene.

HD_API void	_SendPrimsRenamed (const HdSceneIndexObserver::RenamedPrimEntries &entries)
	Notify attached observers of prims (and their descendents) which have been renamed or reparented.

HD_API bool	_IsObserved () const
	Returns whether the scene index has any registered observers; this information can be used to skip work preparing notices when there are no observers.

virtual HD_API void	_SystemMessage (const TfToken &messageType, const HdDataSourceBaseHandle &args)
	Implement in order to react directly to system messages sent from downstream.

Protected Member Functions inherited from TfWeakBase
TfRefPtr< Tf_Remnant >	_Register () const

template<class T >
TfRefPtr< Tf_Remnant >	_Register (T *tempRmnt) const

bool	_HasRemnant () const

Additional Inherited Members
Public Types inherited from TfRefBase
typedef void(*	UniqueChangedFuncPtr) (TfRefBase const *, bool)

Detailed Description

Scene index that resolves velocity-based motion for all prims that support it.

For a complete discussion of how velocity-based motion works, when it is valid, and how it is resolved, see the UsdGeom documentation here: https://openusd.org/dev/api/usd_geom_page_front.html#UsdGeom_VelocityInterpolation

This scene index performs all the necessary calculations so that downstream consumers do not need to worry about velocity-based motion. Downstream consumers need only make the usual call to GetContributingSampleTimesForInterval() for an affected primvar, then sample the primvar's value at the given times.

Affected primvars are: For points-based geometry:

points For point instancers:
instancePositions
instanceRotations
instanceScales

There is no need for downstream consumers to query velocities, accelerations, or angularVelocities; their effects have already been applied to the sampled values when appropriate. Downstream consumers will only see motion (or none), again, as appropriate for the sampled primvar. Any distinction between motion due to velocities and motion due to USD value interpolation is intentionally lost.

Note that, where non-linear motion has been applied (i.e., points or instancePositions with accelerations, or instance rotations with angularVelocities), GetContributingSampleTimesForInterval() will provide the correct number of sample times for non-linear motion, taking UsdGeomMotionAPI's nonlinearSampleCount into consideration. (Downstream consumers should still check nonlinearSampleCount in the case of instanceRotations.)

Additionally, to support certain established workflows, the behavior of the scene index may be controlled by the prim-level Hydra parameter "__velocityMotionMode". This is never read from usd and must instead be authored in a preceding filtering scene index. It is a token with one of the following recognized values:

enable: velocity-based motion is resolved according to the normal rules.
disable: velocity-based motion is frozen to the most recent authored positions/rotations for the current frame.
ignore: velocity-based motion is ignored as if velocities are not present.
noAcceleration: the effect of authored accelerations is ignored.

In all cases (except 'ignore'), __velocityMotionMode has no effect unless the authored velocity data is valid (see link above for what counts as valid). (In the case of 'ignore', validity is not evaluated.) Where the velocity data is not valid, the scene index makes no changes to the incoming scene data, which may indicate motion due to USD value interpolation where appropriate.

Definition at line 95 of file velocityMotionResolvingSceneIndex.h.

Member Function Documentation

◆ _PrimsAdded()

void _PrimsAdded	(	const HdSceneIndexBase &	sender,
		const HdSceneIndexObserver::AddedPrimEntries &	entries
	)

overrideprotectedvirtual

Implements HdSingleInputFilteringSceneIndexBase.

◆ _PrimsDirtied()

void _PrimsDirtied	(	const HdSceneIndexBase &	sender,
		const HdSceneIndexObserver::DirtiedPrimEntries &	entries
	)

overrideprotectedvirtual

Implements HdSingleInputFilteringSceneIndexBase.

◆ _PrimsRemoved()

void _PrimsRemoved	(	const HdSceneIndexBase &	sender,
		const HdSceneIndexObserver::RemovedPrimEntries &	entries
	)

overrideprotectedvirtual

Implements HdSingleInputFilteringSceneIndexBase.

◆ GetChildPrimPaths()

HDSI_API SdfPathVector GetChildPrimPaths ( const SdfPath & primPath ) const

overridevirtual

Returns the paths of all scene index prims located immediately below primPath.

This function can be used to traverse the scene by recursing from SdfPath::AbsoluteRootPath. The traveral is expected to give exactly the set of paths where prim exists as defined in GetPrim. The traversal is also expected to give the same set of prims as the flattening of the scene index's PrimsAdded and PrimsRemoved messages.

This function is expected to be threadsafe.

Implements HdSceneIndexBase.

◆ GetPrim()

HDSI_API HdSceneIndexPrim GetPrim ( const SdfPath & primPath ) const

overridevirtual

Returns a pair of (prim type, datasource).

A prim exists at primPath if and only if datasource is a non-null pointer. In particular, we consider the prim to exist even if the prim type or the container that datasource points to is empty.

Note that we require GetChildPrimPaths to be consistent with this notion of prim existence. That is, unless primPath is the absolute root path, the prim at primPath exists if and only if primPath is contained in GetChildPrimPaths of the parent path.

This function is expected to be threadsafe.

Implements HdSceneIndexBase.

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

pxr/imaging/hdsi/velocityMotionResolvingSceneIndex.h

Public Member Functions

Static Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ _PrimsAdded()

◆ _PrimsDirtied()

◆ _PrimsRemoved()

◆ GetChildPrimPaths()

◆ GetPrim()