usdrt::UsdGeomSubset

Defined in usdrt/scenegraph/usd/usdGeom/subset.h

class UsdGeomSubset : public usdrt::UsdTyped 

Encodes a subset of a piece of geometry (i.e. a UsdGeomImageable) as a set of indices. Currently only supports encoding of face-subsets, but could be extended in the future to support subsets representing edges, segments, points etc.

To apply to a geometric prim, a GeomSubset prim must be the prim’s direct child in namespace, and possess a concrete defining specifier (i.e. def). This restriction makes it easy and efficient to discover subsets of a prim. We might want to relax this restriction if it’s common to have multiple families of subsets on a gprim and if it’s useful to be able to organize subsets belonging to a family under a common scope. See ‘familyName’ attribute for more info on defining a family of subsets.

Note that a GeomSubset isn’t an imageable (i.e. doesn’t derive from UsdGeomImageable). So, you can’t author visibility for it or override its purpose.

Materials are bound to GeomSubsets just as they are for regular geometry using API available in UsdShade (UsdShadeMaterial::Bind).

For any described attribute Fallback Value or Allowed Values below that are text/tokens, the actual token is published and defined in UsdGeomTokens. So to set an attribute to the value “rightHanded”, use UsdGeomTokens->rightHanded as the value.

Public Functions

inline explicit UsdGeomSubset(const UsdPrim &prim = UsdPrim()): Construct a UsdGeomSubset on UsdPrim prim. Equivalent to UsdGeomSubset::Get(prim.GetStage(), prim.GetPath()) for a valid prim , but will not immediately throw an error for an invalid prim.

inline explicit UsdGeomSubset(const UsdSchemaBase &schemaObj): Construct a UsdGeomSubset on the prim held by schemaObj . Should be preferred over UsdGeomSubset(schemaObj.GetPrim()), as it preserves SchemaBase state.

inline virtual ~UsdGeomSubset(): Destructor.

inline UsdAttribute GetElementTypeAttr() const

The type of element that the indices target. Currently only allows “face” and defaults to it.


Declaration	`uniform token elementType = "face"`
C++ Type	TfToken
Usd Type	SdfValueTypeNames->Token
Variability	SdfVariabilityUniform
Allowed Values	face

inline UsdAttribute CreateElementTypeAttr() const: See GetElementTypeAttr(), 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.

inline UsdAttribute GetIndicesAttr() const

The set of indices included in this subset. The indices need not be sorted, but the same index should not appear more than once.


Declaration	`int[] indices = []`
C++ Type	VtArray<int>
Usd Type	SdfValueTypeNames->IntArray

inline UsdAttribute CreateIndicesAttr() const: See GetIndicesAttr(), 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.

inline UsdAttribute GetFamilyNameAttr() const

The name of the family of subsets that this subset belongs to. This is optional and is primarily useful when there are multiple families of subsets under a geometric prim. In some cases, this could also be used for achieving proper roundtripping of subset data between DCC apps. When multiple subsets belonging to a prim have the same familyName, they are said to belong to the family. A familyType value can be encoded on the owner of a family of subsets as a token using the static method UsdGeomSubset::SetFamilyType(). “familyType” can have one of the following values:

UsdGeomTokens->partition: implies that every element of the whole geometry appears exactly once in only one of the subsets belonging to the family.
UsdGeomTokens->nonOverlapping: an element that appears in one subset may not appear in any other subset belonging to the family.
UsdGeomTokens->unrestricted: implies that there are no restrictions w.r.t. the membership of elements in the subsets. They could be overlapping and the union of all subsets in the family may not represent the whole.


Declaration	`uniform token familyName = ""`
C++ Type	TfToken
Usd Type	SdfValueTypeNames->Token
Variability	SdfVariabilityUniform

Note

The validity of subset data is not enforced by the authoring APIs, however they can be checked using UsdGeomSubset::ValidateFamily().

inline UsdAttribute CreateFamilyNameAttr() const: See GetFamilyNameAttr(), 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.

UsdPrim GetPrim() const: Return this schema object’s held prim.

SdfPath GetPath() const: Return the SdfPath to this schema object’s held prim.

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.