usdrt::UsdVolVolume
Defined in usdrt/scenegraph/usd/usdVol/volume.h
-
class UsdVolVolume : public usdrt::UsdGeomGprim
A renderable volume primitive. A volume is made up of any number of FieldBase primitives bound together in this volume. Each FieldBase primitive is specified as a relationship with a namespace prefix of “field”.
The relationship name is used by the renderer to associate individual fields with the named input parameters on the volume shader. Using this indirect approach to connecting fields to shader parameters (rather than using the field prim’s name) allows a single field to be reused for different shader inputs, or to be used as different shader parameters when rendering different Volumes. This means that the name of the field prim is not relevant to its contribution to the volume prims which refer to it. Nor does the field prim’s location in the scene graph have any relevance, and Volumes may refer to fields anywhere in the scene graph. However, unless Field prims need to be shared by multiple Volumes, a Volume’s Field prims should be located under the Volume in namespace, for enhanced organization.
Public Functions
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inline explicit UsdVolVolume(const UsdPrim &prim = UsdPrim())
Construct a UsdVolVolume on UsdPrim
prim
. Equivalent to UsdVolVolume::Get(prim.GetStage(), prim.GetPath()) for a validprim
, but will not immediately throw an error for an invalidprim
.
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inline explicit UsdVolVolume(const UsdSchemaBase &schemaObj)
Construct a UsdVolVolume on the prim held by
schemaObj
. Should be preferred over UsdVolVolume(schemaObj.GetPrim()), as it preserves SchemaBase state.
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inline virtual ~UsdVolVolume()
Destructor.
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inline UsdAttribute GetDisplayColorAttr() const
It is useful to have an “official” colorSet that can be used as a display or modeling color, even in the absence of any specified shader for a gprim. DisplayColor serves this role; because it is a UsdGeomPrimvar, it can also be used as a gprim override for any shader that consumes a displayColor parameter.
Declaration
color3f[] primvars:displayColor
C++ Type
VtArray<GfVec3f>
Usd Type
SdfValueTypeNames->Color3fArray
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inline UsdAttribute CreateDisplayColorAttr() const
See GetDisplayColorAttr(), 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) ifwriteSparsely
istrue
- the default forwriteSparsely
isfalse
.
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inline UsdAttribute GetDisplayOpacityAttr() const
Companion to displayColor that specifies opacity, broken out as an independent attribute rather than an rgba color, both so that each can be independently overridden, and because shaders rarely consume rgba parameters.
Declaration
float[] primvars:displayOpacity
C++ Type
VtArray<float>
Usd Type
SdfValueTypeNames->FloatArray
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inline UsdAttribute CreateDisplayOpacityAttr() const
See GetDisplayOpacityAttr(), 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) ifwriteSparsely
istrue
- the default forwriteSparsely
isfalse
.
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inline UsdAttribute GetDoubleSidedAttr() const
Although some renderers treat all parametric or polygonal surfaces as if they were effectively laminae with outward-facing normals on both sides, some renderers derive significant optimizations by considering these surfaces to have only a single outward side, typically determined by control-point winding order and/or orientation. By doing so they can perform “backface culling” to avoid drawing the many polygons of most closed surfaces that face away from the viewer.
However, it is often advantageous to model thin objects such as paper and cloth as single, open surfaces that must be viewable from both sides, always. Setting a gprim’s doubleSided attribute to
true
instructs all renderers to disable optimizations such as backface culling for the gprim, and attempt (not all renderers are able to do so, but the USD reference GL renderer always will) to provide forward-facing normals on each side of the surface for lighting calculations.Declaration
uniform bool doubleSided = 0
C++ Type
bool
Usd Type
SdfValueTypeNames->Bool
Variability
SdfVariabilityUniform
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inline UsdAttribute CreateDoubleSidedAttr() const
See GetDoubleSidedAttr(), 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) ifwriteSparsely
istrue
- the default forwriteSparsely
isfalse
.
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inline UsdAttribute GetOrientationAttr() const
Orientation specifies whether the gprim’s surface normal should be computed using the right hand rule, or the left hand rule. Please see UsdGeom_WindingOrder for a deeper explanation and generalization of orientation to composed scenes with transformation hierarchies.
Declaration
uniform token orientation = "rightHanded"
C++ Type
Usd Type
SdfValueTypeNames->Token
Variability
SdfVariabilityUniform
Allowed Values
rightHanded, leftHanded
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inline UsdAttribute CreateOrientationAttr() const
See GetOrientationAttr(), 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) ifwriteSparsely
istrue
- the default forwriteSparsely
isfalse
.
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inline UsdAttribute GetExtentAttr() const
Extent is a three dimensional range measuring the geometric extent of the authored gprim in its own local space (i.e. its own transform not applied), without accounting for any shader-induced displacement. If any extent value has been authored for a given Boundable, then it should be authored at every timeSample at which geometry-affecting properties are authored, to ensure correct evaluation via ComputeExtent(). If no extent value has been authored, then ComputeExtent() will call the Boundable’s registered ComputeExtentFunction(), which may be expensive, which is why we strongly encourage proper authoring of extent.
An authored extent on a prim which has children is expected to include the extent of all children, as they will be pruned from BBox computation during traversal.
See also
ComputeExtent()
See also
Why Extent and not Bounds ?.
Declaration
float3[] extent
C++ Type
VtArray<GfVec3f>
Usd Type
SdfValueTypeNames->Float3Array
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inline UsdAttribute CreateExtentAttr() const
See GetExtentAttr(), 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) ifwriteSparsely
istrue
- the default forwriteSparsely
isfalse
.
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inline UsdAttribute GetXformOpOrderAttr() const
Encodes the sequence of transformation operations in the order in which they should be pushed onto a transform stack while visiting a UsdStage’s prims in a graph traversal that will effect the desired positioning for this prim and its descendant prims.
You should rarely, if ever, need to manipulate this attribute directly. It is managed by the AddXformOp(), SetResetXformStack(), and SetXformOpOrder(), and consulted by GetOrderedXformOps() and GetLocalTransformation().
Declaration
uniform token[] xformOpOrder
C++ Type
VtArray<TfToken>
Usd Type
SdfValueTypeNames->TokenArray
Variability
SdfVariabilityUniform
-
inline UsdAttribute CreateXformOpOrderAttr() const
See GetXformOpOrderAttr(), 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) ifwriteSparsely
istrue
- the default forwriteSparsely
isfalse
.
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inline UsdAttribute GetVisibilityAttr() const
Visibility is meant to be the simplest form of “pruning” visibility that is supported by most DCC apps. Visibility is animatable, allowing a sub-tree of geometry to be present for some segment of a shot, and absent from others; unlike the action of deactivating geometry prims, invisible geometry is still available for inspection, for positioning, for defining volumes, etc.
Declaration
token visibility = "inherited"
C++ Type
Usd Type
SdfValueTypeNames->Token
Allowed Values
inherited, invisible
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inline UsdAttribute CreateVisibilityAttr() const
See GetVisibilityAttr(), 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) ifwriteSparsely
istrue
- the default forwriteSparsely
isfalse
.
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inline UsdAttribute GetPurposeAttr() const
Purpose is a classification of geometry into categories that can each be independently included or excluded from traversals of prims on a stage, such as rendering or bounding-box computation traversals.
See UsdGeom_ImageablePurpose for more detail about how purpose is computed and used.
Declaration
uniform token purpose = "default"
C++ Type
Usd Type
SdfValueTypeNames->Token
Variability
SdfVariabilityUniform
Allowed Values
default, render, proxy, guide
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inline UsdAttribute CreatePurposeAttr() const
See GetPurposeAttr(), 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) ifwriteSparsely
istrue
- the default forwriteSparsely
isfalse
.
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inline UsdRelationship GetProxyPrimRel() const
The proxyPrim relationship allows us to link a prim whose purpose is “render” to its (single target) purpose=”proxy” prim. This is entirely optional, but can be useful in several scenarios:
In a pipeline that does pruning (for complexity management) by deactivating prims composed from asset references, when we deactivate a purpose=”render” prim, we will be able to discover and additionally deactivate its associated purpose=”proxy” prim, so that preview renders reflect the pruning accurately.
DCC importers may be able to make more aggressive optimizations for interactive processing and display if they can discover the proxy for a given render prim.
With a little more work, a Hydra-based application will be able to map a picked proxy prim back to its render geometry for selection.
Note
It is only valid to author the proxyPrim relationship on prims whose purpose is “render”.
-
inline UsdRelationship CreateProxyPrimRel() const
See GetProxyPrimRel(), and also Create vs Get Property Methods for when to use Get vs Create.
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inline explicit operator bool() const
Check if this schema object is compatible with it’s held prim and that the prim is valid.
A typed schema object is compatible if the held prim’s type is or is a subtype of the schema’s type. Based on
prim.IsA()
.An API schema object is compatible if the API is of type SingleApplyAPI or UsdSchemaType::MultipleApplyAPI, and the schema has been applied to the prim. Based on
prim.HasAPI
.This method invokes polymorphic behaviour.
See also
- Returns
True if the help prim is valid, and the schema object is compatible with its held prim.
Public Static Functions
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static inline UsdVolVolume Define(const UsdStageRefPtr &stage, const SdfPath &path)
Attempt to ensure a UsdPrim adhering to this schema at
path
is defined (according to UsdPrim::IsDefined()) on this stage.
Public Static Attributes
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static const UsdSchemaType schemaType = UsdSchemaType::ConcreteTyped
Compile time constant representing what kind of schema this class is.
See also
Protected Functions
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inline virtual bool _IsCompatible() const
Helper for subclasses to do specific compatibility checking with the given prim. Subclassess may override
_isCompatible
to for example check type compatibility or value compatibility on the prim.Overrides exist for UsdTyped and UsdAPISchemaBase.
This check is called when clients invoke the bool operator.
- Returns
True if the schema object is compatible with its held prim.
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inline explicit UsdVolVolume(const UsdPrim &prim = UsdPrim())