UsdGeomMotionAPI Class Reference

UsdGeomMotionAPI encodes data that can live on any prim that may affect computations involving: More...

+ Inheritance diagram for UsdGeomMotionAPI:

Public Member Functions

 UsdGeomMotionAPI (const UsdPrim &prim=UsdPrim())
 Construct a UsdGeomMotionAPI on UsdPrim prim . More...
 
 UsdGeomMotionAPI (const UsdSchemaBase &schemaObj)
 Construct a UsdGeomMotionAPI on the prim held by schemaObj . More...
 
virtual USDGEOM_API ~UsdGeomMotionAPI ()
 Destructor. More...
 
USDGEOM_API UsdAttribute GetMotionBlurScaleAttr () const
 BlurScale is an inherited float attribute that stipulates the rendered motion blur (as typically specified via UsdGeomCamera's shutter:open and shutter:close properties) should be scaled for all objects at and beneath the prim in namespace on which the motion:blurScale value is specified. More...
 
USDGEOM_API UsdAttribute CreateMotionBlurScaleAttr (VtValue const &defaultValue=VtValue(), bool writeSparsely=false) const
 See GetMotionBlurScaleAttr(), and also Create vs Get Property Methods for when to use Get vs Create. More...
 
USDGEOM_API UsdAttribute GetVelocityScaleAttr () const
 
USDGEOM_API UsdAttribute CreateVelocityScaleAttr (VtValue const &defaultValue=VtValue(), bool writeSparsely=false) const
 See GetVelocityScaleAttr(), and also Create vs Get Property Methods for when to use Get vs Create. More...
 
USDGEOM_API UsdAttribute GetNonlinearSampleCountAttr () const
 Determines the number of position or transformation samples created when motion is described by attributes contributing non-linear terms. More...
 
USDGEOM_API UsdAttribute CreateNonlinearSampleCountAttr (VtValue const &defaultValue=VtValue(), bool writeSparsely=false) const
 See GetNonlinearSampleCountAttr(), and also Create vs Get Property Methods for when to use Get vs Create. More...
 
USDGEOM_API float ComputeVelocityScale (UsdTimeCode time=UsdTimeCode::Default()) const
 
USDGEOM_API int ComputeNonlinearSampleCount (UsdTimeCode time=UsdTimeCode::Default()) const
 Compute the inherited value of nonlinearSampleCount at time, i.e. More...
 
USDGEOM_API float ComputeMotionBlurScale (UsdTimeCode time=UsdTimeCode::Default()) const
 Compute the inherited value of motion:blurScale at time, i.e. More...
 
- Public Member Functions inherited from UsdAPISchemaBase
 UsdAPISchemaBase (const UsdPrim &prim=UsdPrim())
 Construct a UsdAPISchemaBase on UsdPrim prim . More...
 
 UsdAPISchemaBase (const UsdSchemaBase &schemaObj)
 Construct a UsdAPISchemaBase on the prim held by schemaObj . More...
 
virtual USD_API ~UsdAPISchemaBase ()=0
 Destructor. More...
 
- Public Member Functions inherited from UsdSchemaBase
bool IsConcrete () const
 Returns whether or not this class corresponds to a concrete instantiable prim type in scene description. More...
 
bool IsTyped () const
 Returns whether or not this class inherits from UsdTyped. More...
 
bool IsAPISchema () const
 Returns whether this is an API schema or not. More...
 
bool IsAppliedAPISchema () const
 Returns whether this is an applied API schema or not. More...
 
bool IsMultipleApplyAPISchema () const
 Returns whether this is an applied API schema or not. More...
 
UsdSchemaKind GetSchemaKind () const
 Returns the kind of schema this class is. More...
 
USD_API UsdSchemaBase (const UsdPrim &prim=UsdPrim())
 Construct and store prim as the held prim. More...
 
USD_API UsdSchemaBase (const UsdSchemaBase &otherSchema)
 Construct and store for the same prim held by otherSchema. More...
 
virtual USD_API ~UsdSchemaBase ()
 Destructor. More...
 
USD_API operator bool () const
 
UsdPrim GetPrim () const
 Return this schema object's held prim. More...
 
SdfPath GetPath () const
 Shorthand for GetPrim()->GetPath(). More...
 
USD_API const UsdPrimDefinitionGetSchemaClassPrimDefinition () const
 Return the prim definition associated with this schema instance if one exists, otherwise return null. More...
 

Static Public Member Functions

static USDGEOM_API const TfTokenVectorGetSchemaAttributeNames (bool includeInherited=true)
 Return a vector of names of all pre-declared attributes for this schema class and all its ancestor classes. More...
 
static USDGEOM_API UsdGeomMotionAPI Get (const UsdStagePtr &stage, const SdfPath &path)
 Return a UsdGeomMotionAPI holding the prim adhering to this schema at path on stage. More...
 
static USDGEOM_API bool CanApply (const UsdPrim &prim, std::string *whyNot=nullptr)
 Returns true if this single-apply API schema can be applied to the given prim. More...
 
static USDGEOM_API UsdGeomMotionAPI Apply (const UsdPrim &prim)
 Applies this single-apply API schema to the given prim. More...
 
- Static Public Member Functions inherited from UsdAPISchemaBase
static USD_API const TfTokenVectorGetSchemaAttributeNames (bool includeInherited=true)
 Return a vector of names of all pre-declared attributes for this schema class and all its ancestor classes. More...
 
- Static Public Member Functions inherited from UsdSchemaBase
static const TfTokenVectorGetSchemaAttributeNames (bool includeInherited=true)
 

Static Public Attributes

static const UsdSchemaKind schemaKind = UsdSchemaKind::SingleApplyAPI
 Compile time constant representing what kind of schema this class is. More...
 
- Static Public Attributes inherited from UsdAPISchemaBase
static const UsdSchemaKind schemaKind = UsdSchemaKind::AbstractBase
 Compile time constant representing what kind of schema this class is. More...
 
- Static Public Attributes inherited from UsdSchemaBase
static const UsdSchemaKind schemaKind = UsdSchemaKind::AbstractBase
 Compile time constant representing what kind of schema this class is. More...
 

Protected Member Functions

USDGEOM_API UsdSchemaKind _GetSchemaKind () const override
 Returns the kind of schema this class belongs to. More...
 
- Protected Member Functions inherited from UsdAPISchemaBase
 UsdAPISchemaBase (const UsdPrim &prim, const TfToken &instanceName)
 Construct a multiple-apply UsdAPISchemaBase on UsdPrim prim with the specified instanceName. More...
 
 UsdAPISchemaBase (const UsdSchemaBase &schemaObj, const TfToken &instanceName)
 Construct a multiple-apply UsdAPISchemaBase on the prim held by schemaObj with the given instanceName. More...
 
const TfToken_GetInstanceName () const
 Returns the instance name of the API schema object belonging to a multiple-apply API schema. More...
 
USD_API bool _IsCompatible () const override
 Check whether this APISchema object is valid for the currently held. More...
 
- Protected Member Functions inherited from UsdSchemaBase
virtual UsdSchemaKind _GetSchemaType () const
 
const TfType_GetType () const
 
USD_API UsdAttribute _CreateAttr (TfToken const &attrName, SdfValueTypeName const &typeName, bool custom, SdfVariability variability, VtValue const &defaultValue, bool writeSparsely) const
 

Friends

class UsdSchemaRegistry
 

Detailed Description

UsdGeomMotionAPI encodes data that can live on any prim that may affect computations involving:

  • computed motion for motion blur
  • sampling for motion blur

The motion:blurScale attribute allows artists to scale the amount of motion blur to be rendered for parts of the scene without changing the recorded animation. See Effectively Applying motion:blurScale for use and implementation details.

Definition at line 67 of file motionAPI.h.

Constructor & Destructor Documentation

◆ UsdGeomMotionAPI() [1/2]

UsdGeomMotionAPI ( const UsdPrim prim = UsdPrim())
inlineexplicit

Construct a UsdGeomMotionAPI on UsdPrim prim .

Equivalent to UsdGeomMotionAPI::Get(prim.GetStage(), prim.GetPath()) for a valid prim, but will not immediately throw an error for an invalid prim

Definition at line 79 of file motionAPI.h.

◆ UsdGeomMotionAPI() [2/2]

UsdGeomMotionAPI ( const UsdSchemaBase schemaObj)
inlineexplicit

Construct a UsdGeomMotionAPI on the prim held by schemaObj .

Should be preferred over UsdGeomMotionAPI(schemaObj.GetPrim()), as it preserves SchemaBase state.

Definition at line 87 of file motionAPI.h.

◆ ~UsdGeomMotionAPI()

virtual USDGEOM_API ~UsdGeomMotionAPI ( )
virtual

Destructor.

Member Function Documentation

◆ _GetSchemaKind()

USDGEOM_API UsdSchemaKind _GetSchemaKind ( ) const
overrideprotectedvirtual

Returns the kind of schema this class belongs to.

See also
UsdSchemaKind

Reimplemented from UsdAPISchemaBase.

◆ Apply()

static USDGEOM_API UsdGeomMotionAPI Apply ( const UsdPrim prim)
static

Applies this single-apply API schema to the given prim.

This information is stored by adding "MotionAPI" to the token-valued, listOp metadata apiSchemas on the prim.

Returns
A valid UsdGeomMotionAPI object is returned upon success. An invalid (or empty) UsdGeomMotionAPI object is returned upon failure. See UsdPrim::ApplyAPI() for conditions resulting in failure.
See also
UsdPrim::GetAppliedSchemas()
UsdPrim::HasAPI()
UsdPrim::CanApplyAPI()
UsdPrim::ApplyAPI()
UsdPrim::RemoveAPI()

◆ CanApply()

static USDGEOM_API bool CanApply ( const UsdPrim prim,
std::string *  whyNot = nullptr 
)
static

Returns true if this single-apply API schema can be applied to the given prim.

If this schema can not be a applied to the prim, this returns false and, if provided, populates whyNot with the reason it can not be applied.

Note that if CanApply returns false, that does not necessarily imply that calling Apply will fail. Callers are expected to call CanApply before calling Apply if they want to ensure that it is valid to apply a schema.

See also
UsdPrim::GetAppliedSchemas()
UsdPrim::HasAPI()
UsdPrim::CanApplyAPI()
UsdPrim::ApplyAPI()
UsdPrim::RemoveAPI()

◆ ComputeMotionBlurScale()

USDGEOM_API float ComputeMotionBlurScale ( UsdTimeCode  time = UsdTimeCode::Default()) const

Compute the inherited value of motion:blurScale at time, i.e.

the authored value on the prim closest to this prim in namespace, resolved upwards through its ancestors in namespace.

Returns
the inherited value, or 1.0 if neither the prim nor any of its ancestors possesses an authored value.
Note
this is a reference implementation that is not particularly efficient if evaluating over many prims, because it does not share inherited results.

◆ ComputeNonlinearSampleCount()

USDGEOM_API int ComputeNonlinearSampleCount ( UsdTimeCode  time = UsdTimeCode::Default()) const

Compute the inherited value of nonlinearSampleCount at time, i.e.

the authored value on the prim closest to this prim in namespace, resolved upwards through its ancestors in namespace.

Returns
the inherited value, or 3 if neither the prim nor any of its ancestors possesses an authored value.
Note
this is a reference implementation that is not particularly efficient if evaluating over many prims, because it does not share inherited results.

◆ ComputeVelocityScale()

USDGEOM_API float ComputeVelocityScale ( UsdTimeCode  time = UsdTimeCode::Default()) const
Deprecated:

Compute the inherited value of velocityScale at time, i.e. the authored value on the prim closest to this prim in namespace, resolved upwards through its ancestors in namespace.

Returns
the inherited value, or 1.0 if neither the prim nor any of its ancestors possesses an authored value.
Note
this is a reference implementation that is not particularly efficient if evaluating over many prims, because it does not share inherited results.

◆ CreateMotionBlurScaleAttr()

USDGEOM_API UsdAttribute CreateMotionBlurScaleAttr ( VtValue const &  defaultValue = VtValue(),
bool  writeSparsely = false 
) const

See GetMotionBlurScaleAttr(), and also Create vs Get Property Methods for when to use Get vs Create.

If specified, author defaultValue as the attribute's default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

◆ CreateNonlinearSampleCountAttr()

USDGEOM_API UsdAttribute CreateNonlinearSampleCountAttr ( VtValue const &  defaultValue = VtValue(),
bool  writeSparsely = false 
) const

See GetNonlinearSampleCountAttr(), and also Create vs Get Property Methods for when to use Get vs Create.

If specified, author defaultValue as the attribute's default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

◆ CreateVelocityScaleAttr()

USDGEOM_API UsdAttribute CreateVelocityScaleAttr ( VtValue const &  defaultValue = VtValue(),
bool  writeSparsely = false 
) const

See GetVelocityScaleAttr(), and also Create vs Get Property Methods for when to use Get vs Create.

If specified, author defaultValue as the attribute's default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

◆ Get()

static USDGEOM_API UsdGeomMotionAPI Get ( const UsdStagePtr &  stage,
const SdfPath path 
)
static

Return a UsdGeomMotionAPI holding the prim adhering to this schema at path on stage.

If no prim exists at path on stage, or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following:

UsdGeomMotionAPI(stage->GetPrimAtPath(path));

◆ GetMotionBlurScaleAttr()

USDGEOM_API UsdAttribute GetMotionBlurScaleAttr ( ) const

BlurScale is an inherited float attribute that stipulates the rendered motion blur (as typically specified via UsdGeomCamera's shutter:open and shutter:close properties) should be scaled for all objects at and beneath the prim in namespace on which the motion:blurScale value is specified.

Without changing any other data in the scene, blurScale allows artists to "dial in" the amount of blur on a per-object basis. A blurScale value of zero removes all blur, a value of 0.5 reduces blur by half, and a value of 2.0 doubles the blur. The legal range for blurScale is [0, inf), although very high values may result in extremely expensive renders, and may exceed the capabilities of some renderers.

Although renderers are free to implement this feature however they see fit, see Effectively Applying motion:blurScale for our guidance on implementing the feature universally and efficiently.

See also
ComputeMotionBlurScale()
Declaration float motion:blurScale = 1
C++ Type float
Usd Type SdfValueTypeNames->Float

◆ GetNonlinearSampleCountAttr()

USDGEOM_API UsdAttribute GetNonlinearSampleCountAttr ( ) const

Determines the number of position or transformation samples created when motion is described by attributes contributing non-linear terms.

To give an example, imagine an application (such as a renderer) consuming 'points' and the USD document also contains 'accelerations' for the same prim. Unless the application can consume these 'accelerations' itself, an intermediate layer has to compute samples within the sampling interval for the point positions based on the value of 'points', 'velocities' and 'accelerations'. The number of these samples is given by 'nonlinearSampleCount'. The samples are equally spaced within the sampling interval.

Another example involves the PointInstancer where 'nonlinearSampleCount' is relevant when 'angularVelocities' or 'accelerations' are authored.

'nonlinearSampleCount' is an inherited attribute, also see ComputeNonlinearSampleCount()

Declaration int motion:nonlinearSampleCount = 3
C++ Type int
Usd Type SdfValueTypeNames->Int

◆ GetSchemaAttributeNames()

static USDGEOM_API const TfTokenVector& GetSchemaAttributeNames ( bool  includeInherited = true)
static

Return a vector of names of all pre-declared attributes for this schema class and all its ancestor classes.

Does not include attributes that may be authored by custom/extended methods of the schemas involved.

◆ GetVelocityScaleAttr()

USDGEOM_API UsdAttribute GetVelocityScaleAttr ( ) const
Deprecated:

VelocityScale is an inherited float attribute that velocity-based schemas (e.g. PointBased, PointInstancer) can consume to compute interpolated positions and orientations by applying velocity and angularVelocity, which is required for interpolating between samples when topology is varying over time. Although these quantities are generally physically computed by a simulator, sometimes we require more or less motion-blur to achieve the desired look.

VelocityScale allows artists to dial-in, as a post-sim correction, a scale factor to be applied to the velocity prior to computing interpolated positions from it.

Declaration float motion:velocityScale = 1
C++ Type float
Usd Type SdfValueTypeNames->Float

Member Data Documentation

◆ schemaKind

const UsdSchemaKind schemaKind = UsdSchemaKind::SingleApplyAPI
static

Compile time constant representing what kind of schema this class is.

See also
UsdSchemaKind

Definition at line 73 of file motionAPI.h.


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