A scene index implementing USD native instancing. More...

Inheritance diagram for UsdImagingNiPrototypePropagatingSceneIndex:

Public Member Functions
USDIMAGING_API HdSceneIndexPrim	GetPrim (const SdfPath &primPath) const override
	Returns a pair of (prim type, datasource) for the object at `primPath`. More...

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

USDIMAGING_API std::vector< HdSceneIndexBaseRefPtr >	GetInputScenes () const override

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

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

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. More...

Public Member Functions inherited from TfRefBase
size_t	GetCurrentCount () const
	Return the current reference count of this object. More...

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

const TfRefCount &	GetRefCount () const

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 USDIMAGING_API UsdImagingNiPrototypePropagatingSceneIndexRefPtr	New (HdSceneIndexBaseRefPtr const &inputSceneIndex)

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

Friends
class	_InstanceAggregationSceneIndexObserver

class	_MergingSceneIndexObserver

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

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

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

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

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. More...

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

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

bool	_HasRemnant () const

Detailed Description

A scene index implementing USD native instancing.

If combined with the UsdImagingPiPrototypePropagatingSceneIndex, the native instancing scene index has to be run after the point instancing scene index.

This scene index uses the UsdImgingNiInstanceAggregationSceneIndex to find all instances, aggregate them and insert instancers for each set of aggregated instances. This scene index then inserts copies of the corresponding USD prototype underneath each of these instancers. Each of these copies is actually a UsdImagingNiPrototypePropagatingSceneIndex itself. This way, we can handle nested native instancing. In other words, we can call the UsdImagingNiPrototypePropagatingSceneIndex for a USD prototype and it will find the instances within that prototype.

The instancing scene index uses the instancedBy:prototypeRoot of the input scene index during aggregation. Typically, the input scene index will be a UsdImagingPiPrototypePropagatingSceneIndex which populates instancedBy:prototypeRoot based on which point instancer is instancing a prim.

This scene index is implemented by a merging scene index. One input to the merging scene index is the UsdImaging_NiPrototypeSceneIndex which prepares the prototype for which this scene index was created. Another input to the merging scene index is the UsdImaging_NiInstanceAggregationSceneIndex that will insert the instancers for the instances within this prototype. The _InstanceAggregationSceneIndexObserver will observe the latter scene index to add respective UsdImagingNiPrototypePropagatingSceneIndex's under each instancer.

Example 1 (also see Example 1 in niInstanceAggregationSceneIndex.h)

USD:

def Xform "MyPrototype" { def Cube "MyCube" { } }

def "Cube_1" ( instanceable = true references = </MyPrototype> { }

Inputs of the UsdImagingNiPrototypePropagatingSceneIndex(inputSceneIndex):

* HdMergingSceneIndex
    * UsdImaging_NiPrototypeSceneIndex
      prototypeRoot = ""
        * HdFlatteningSceneIndex
            * UsdImaging_NiPrototypePruningSceneIndex
              prototypeRoot = ""
                * inputSceneIndex (typically a UsdImagingPiPrototypePropagatingSceneIndex)
    * UsdImaging_NiInstanceAggregationSceneIndex 
        * HdFlatteningSceneIndex
            [... as above]
    * UsdImagingRerootingSceneIndex
      (inserted by _InstanceAggregationSceneIndexObserver::PrimsAdded
       through _MergingSceneIndexEntry)
      srcPrefix = /
      dstPrefix = /__Usd_Prototypes/NoBindings/__Prototype_1
        * UsdImagingNiPrototypePropagatingSceneIndex
          prototypeName = __Prototype_1
            * HdMergingSceneIndex
                * UsdImaging_NiPrototypeSceneIndex
                  prototypeRoot = /__PrototypeRoot1
                    * HdFlatteningSceneIndex
                        * UsdImagingRerootingSceneIndex
                          srcPrefix = /__PrototypeRoot1
                          dstPrefix = /__PrototypeRoot1
                            * inputSceneIndex
                * UsdImaging_NiInstanceAggregationSceneIndex 
                    * HdFlatteningSceneIndex
                        [... as just above]

UsdImagingNiPrototypePropagatingSceneIndex

/Cube_1 primType: "" dataSource: instance: # Useful for translating Usd proxy paths for selection.

See corresponding example in niInstanceAggregationIndex

for more details.

instancer: /__Usd_Prototypes/NoBindings/__Prototype_1 prototypeId: 0 instanceId: 0 /MyPrototype # Not referenced from a different file, so appears here

as non-prototype as well

primType: "" /MyPrototype/MyCube primType: cube /__Usd_Prototypes primType: "" /__Usd_Prototypes/NoBindings primType: "" /__Usd_Prototypes/NoBindings/__Prototype_1 primType: instancer dataSource: instancerTopology: instanceIndices: i0: [ 0 ] prototypes: [ /__Usd_Prototypes/NoBindings/__Prototype_1/__Protoype_1 ] instanceLocations: [ /Cube_1 ] # for picking primvars: instanceTransform: primvarValue: [ identity matrix ] interpolation: instance /__Usd_Prototypes/NoBindings/__Prototype_1/__Prototype_1 primType: "" instancedBy: paths: [ /__Usd_Prototypes/NoBindings/__Prototype_1 ] prototypeRoot: /__Usd_Prototypes/NoBindings/__Prototype_1 /__Prototype_1 /__Usd_Prototypes/NoBindings/__Prototype_1/__Prototype_1/MyCube primType: cube instancedBy: paths: [ /__Usd_Prototypes/NoBindings/__Prototype_1 ] prototypeRoot: /__Usd_Prototypes/NoBindings/__Prototype_1 /__Prototype_1

Example 2:

def Xform "MyNestedPrototype" # Will become USD prototype /__Prototype_1 { def Cube "MyCube" { } }

def Xform "MyPrototype" # Will become USD prototype /__Prototype_2 { def "MyNestedInstance" ( instanceable = true references = </MyNestedPrototype> ) { } }

def Xform "MyInstance" ( instanceable = true references = </MyPrototype>) {

}

UsdImagingNiPrototypePropagatingSceneIndex

... /MyInstance primType: "" dataSource: instance: instancer: /__Usd_Prototypes/NoBindings/__Prototype_2 prototypeId: 0 instanceId: 0 /__UsdPrototypes /__UsdPrototypes/NoBindings primType: "" /__UsdPrototypes/NoBindings/__Prototype_2 primType: instancer dataSource: instanerTopology: prototypes: [ /__UsdPrototypes/NoBindings/__Prototype_2 ] ... /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2 primType: "" /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/MyNestedInstance primType: "" dataSource: instancer: /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/__UsdPrototypes/NoBindings/__Prototype_1 prototypeId: 0 instanceId: 0 /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/__UsdPrototypes /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/__UsdPrototypes/NoBindings primType: "" /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/__UsdPrototypes/NoBindings/__Prototype_1 primType: instancer dataSource: instanerTopology: prototypes: [ /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/__UsdPrototypes/NoBindings/__Prototype_1/__Prototype_1 ] ... instancedBy: paths: [ /__UsdPrototypes/NoBindings/__Prototype_2 ] prototypeRoot: /__UsdPrototypes/NoBindings/__Prototype_2/__Prototype_2 /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/__UsdPrototypes/NoBindings/__Prototype_1/__Prototype_1 primType: "" dataSource: instancedBy: paths: [ /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/__UsdPrototypes/NoBindings/__Prototype_1 ] prototypeRoot: /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/__UsdPrototypes/NoBindings/__Prototype_1/__Prototype_1 /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/__UsdPrototypes/NoBindings/__Prototype_1/__Prototype_1/MyCube primType: "cube" dataSource: instancedBy: paths: [ /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/__UsdPrototypes/NoBindings/__Prototype_1 ] prototypeRoot: /__UsdPrototypes/NoBindings/__Prototype_2/_Prototype_2/__UsdPrototypes/NoBindings/__Prototype_1/__Prototype_1 ...

Definition at line 243 of file niPrototypePropagatingSceneIndex.h.

Member Function Documentation

◆ GetChildPrimPaths()

USDIMAGING_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(); such a traversal is 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.