usdrt::UsdGeomNurbsPatch
Defined in usdrt/scenegraph/usd/usdGeom/nurbsPatch.h
-
class UsdGeomNurbsPatch : public usdrt::UsdGeomPointBased
Encodes a rational or polynomial non-uniform B-spline surface, with optional trim curves.
The encoding mostly follows that of RiNuPatch and RiTrimCurve: https://renderman.pixar.com/resources/current/RenderMan/geometricPrimitives.html#rinupatch , with some minor renaming and coalescing for clarity.
The layout of control vertices in the points attribute inherited from UsdGeomPointBased is row-major with U considered rows, and V columns.
NurbsPatch Form
The authored points, orders, knots, weights, and ranges are all that is required to render the nurbs patch. However, the only way to model closed surfaces with nurbs is to ensure that the first and last control points along the given axis are coincident. Similarly, to ensure the surface is not only closed but also C2 continuous, the last order - 1 control points must be (correspondingly) coincident with the first order - 1 control points, and also the spacing of the last corresponding knots must be the same as the first corresponding knots.
Form is provided as an aid to interchange between modeling and animation applications so that they can robustly identify the intent with which the surface was modelled, and take measures (if they are able) to preserve the continuity/concidence constraints as the surface may be rigged or deformed.
An open-form NurbsPatch has no continuity constraints.
A closed-form NurbsPatch expects the first and last control points to overlap
A periodic-form NurbsPatch expects the first and last order - 1 control points to overlap.
Nurbs are an important modeling primitive in CAD/CAM tools and early computer graphics DCC’s. Because they have a natural UV parameterization they easily support “trim curves”, which allow smooth shapes to be carved out of the surface.
However, the topology of the patch is always rectangular, and joining two nurbs patches together (especially when they have differing numbers of spans) is difficult to do smoothly. Also, nurbs are not supported by the Ptex texturing technology (http://ptex.us).
Neither of these limitations are shared by subdivision surfaces; therefore, although they do not subscribe to trim-curve-based shaping, subdivs are often considered a more flexible modeling primitive.
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 UsdGeomNurbsPatch(const UsdPrim &prim = UsdPrim())
Construct a UsdGeomNurbsPatch on UsdPrim
prim
. Equivalent to UsdGeomNurbsPatch::Get(prim.GetStage(), prim.GetPath()) for a validprim
, but will not immediately throw an error for an invalidprim
.
-
inline explicit UsdGeomNurbsPatch(const UsdSchemaBase &schemaObj)
Construct a UsdGeomNurbsPatch on the prim held by
schemaObj
. Should be preferred over UsdGeomNurbsPatch(schemaObj.GetPrim()), as it preserves SchemaBase state.
-
inline virtual ~UsdGeomNurbsPatch()
Destructor.
-
inline UsdAttribute GetUVertexCountAttr() const
Number of vertices in the U direction. Should be at least as large as uOrder.
Declaration
int uVertexCount
C++ Type
int
Usd Type
SdfValueTypeNames->Int
-
inline UsdAttribute CreateUVertexCountAttr() const
See GetUVertexCountAttr(), 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
.
-
inline UsdAttribute GetVVertexCountAttr() const
Number of vertices in the V direction. Should be at least as large as vOrder.
Declaration
int vVertexCount
C++ Type
int
Usd Type
SdfValueTypeNames->Int
-
inline UsdAttribute CreateVVertexCountAttr() const
See GetVVertexCountAttr(), 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
.
-
inline UsdAttribute GetUOrderAttr() const
Order in the U direction. Order must be positive and is equal to the degree of the polynomial basis to be evaluated, plus 1.
Declaration
int uOrder
C++ Type
int
Usd Type
SdfValueTypeNames->Int
-
inline UsdAttribute CreateUOrderAttr() const
See GetUOrderAttr(), 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
.
-
inline UsdAttribute GetVOrderAttr() const
Order in the V direction. Order must be positive and is equal to the degree of the polynomial basis to be evaluated, plus 1.
Declaration
int vOrder
C++ Type
int
Usd Type
SdfValueTypeNames->Int
-
inline UsdAttribute CreateVOrderAttr() const
See GetVOrderAttr(), 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
.
-
inline UsdAttribute GetUKnotsAttr() const
Knot vector for U direction providing U parameterization. The length of this array must be ( uVertexCount + uOrder ), and its entries must take on monotonically increasing values.
Declaration
double[] uKnots
C++ Type
VtArray<double>
Usd Type
SdfValueTypeNames->DoubleArray
-
inline UsdAttribute CreateUKnotsAttr() const
See GetUKnotsAttr(), 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
.
-
inline UsdAttribute GetVKnotsAttr() const
Knot vector for V direction providing U parameterization. The length of this array must be ( vVertexCount + vOrder ), and its entries must take on monotonically increasing values.
Declaration
double[] vKnots
C++ Type
VtArray<double>
Usd Type
SdfValueTypeNames->DoubleArray
-
inline UsdAttribute CreateVKnotsAttr() const
See GetVKnotsAttr(), 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
.
-
inline UsdAttribute GetUFormAttr() const
Interpret the control grid and knot vectors as representing an open, geometrically closed, or geometrically closed and C2 continuous surface along the U dimension.
Declaration
uniform token uForm = "open"
C++ Type
Usd Type
SdfValueTypeNames->Token
Variability
SdfVariabilityUniform
Allowed Values
open, closed, periodic
See also
NurbsPatch Form
-
inline UsdAttribute CreateUFormAttr() const
See GetUFormAttr(), 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
.
-
inline UsdAttribute GetVFormAttr() const
Interpret the control grid and knot vectors as representing an open, geometrically closed, or geometrically closed and C2 continuous surface along the V dimension.
Declaration
uniform token vForm = "open"
C++ Type
Usd Type
SdfValueTypeNames->Token
Variability
SdfVariabilityUniform
Allowed Values
open, closed, periodic
See also
NurbsPatch Form
-
inline UsdAttribute CreateVFormAttr() const
See GetVFormAttr(), 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
.
-
inline UsdAttribute GetURangeAttr() const
Provides the minimum and maximum parametric values (as defined by uKnots) over which the surface is actually defined. The minimum must be less than the maximum, and greater than or equal to the value of uKnots[uOrder-1]. The maxium must be less than or equal to the last element’s value in uKnots.
Declaration
double2 uRange
C++ Type
GfVec2d
Usd Type
SdfValueTypeNames->Double2
-
inline UsdAttribute CreateURangeAttr() const
See GetURangeAttr(), 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
.
-
inline UsdAttribute GetVRangeAttr() const
Provides the minimum and maximum parametric values (as defined by vKnots) over which the surface is actually defined. The minimum must be less than the maximum, and greater than or equal to the value of vKnots[vOrder-1]. The maxium must be less than or equal to the last element’s value in vKnots.
Declaration
double2 vRange
C++ Type
GfVec2d
Usd Type
SdfValueTypeNames->Double2
-
inline UsdAttribute CreateVRangeAttr() const
See GetVRangeAttr(), 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
.
-
inline UsdAttribute GetPointWeightsAttr() const
Optionally provides “w” components for each control point, thus must be the same length as the points attribute. If authored, the patch will be rational. If unauthored, the patch will be polynomial, i.e. weight for all points is 1.0.
Declaration
double[] pointWeights
C++ Type
VtArray<double>
Usd Type
SdfValueTypeNames->DoubleArray
Note
Some DCC’s pre-weight the points, but in this schema, points are not pre-weighted.
-
inline UsdAttribute CreatePointWeightsAttr() const
See GetPointWeightsAttr(), 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
.
-
inline UsdAttribute GetTrimCurveCountsAttr() const
Each element specifies how many curves are present in each “loop” of the trimCurve, and the length of the array determines how many loops the trimCurve contains. The sum of all elements is the total nuber of curves in the trim, to which we will refer as nCurves in describing the other trim attributes.
Declaration
int[] trimCurve:counts
C++ Type
VtArray<int>
Usd Type
SdfValueTypeNames->IntArray
-
inline UsdAttribute CreateTrimCurveCountsAttr() const
See GetTrimCurveCountsAttr(), 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
.
-
inline UsdAttribute GetTrimCurveOrdersAttr() const
Flat list of orders for each of the nCurves curves.
Declaration
int[] trimCurve:orders
C++ Type
VtArray<int>
Usd Type
SdfValueTypeNames->IntArray
-
inline UsdAttribute CreateTrimCurveOrdersAttr() const
See GetTrimCurveOrdersAttr(), 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
.
-
inline UsdAttribute GetTrimCurveVertexCountsAttr() const
Flat list of number of vertices for each of the nCurves curves.
Declaration
int[] trimCurve:vertexCounts
C++ Type
VtArray<int>
Usd Type
SdfValueTypeNames->IntArray
-
inline UsdAttribute CreateTrimCurveVertexCountsAttr() const
See GetTrimCurveVertexCountsAttr(), 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
.
-
inline UsdAttribute GetTrimCurveKnotsAttr() const
Flat list of parametric values for each of the nCurves curves. There will be as many knots as the sum over all elements of vertexCounts plus the sum over all elements of orders.
Declaration
double[] trimCurve:knots
C++ Type
VtArray<double>
Usd Type
SdfValueTypeNames->DoubleArray
-
inline UsdAttribute CreateTrimCurveKnotsAttr() const
See GetTrimCurveKnotsAttr(), 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
.
-
inline UsdAttribute GetTrimCurveRangesAttr() const
Flat list of minimum and maximum parametric values (as defined by knots) for each of the nCurves curves.
Declaration
double2[] trimCurve:ranges
C++ Type
VtArray<GfVec2d>
Usd Type
SdfValueTypeNames->Double2Array
-
inline UsdAttribute CreateTrimCurveRangesAttr() const
See GetTrimCurveRangesAttr(), 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
.
-
inline UsdAttribute GetTrimCurvePointsAttr() const
Flat list of homogeneous 2D points (u, v, w) that comprise the nCurves curves. The number of points should be equal to the um over all elements of vertexCounts.
Declaration
double3[] trimCurve:points
C++ Type
VtArray<GfVec3d>
Usd Type
SdfValueTypeNames->Double3Array
-
inline UsdAttribute CreateTrimCurvePointsAttr() const
See GetTrimCurvePointsAttr(), 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
.
-
inline UsdAttribute GetPointsAttr() const
The primary geometry attribute for all PointBased primitives, describes points in (local) space.
Declaration
point3f[] points
C++ Type
VtArray<GfVec3f>
Usd Type
SdfValueTypeNames->Point3fArray
-
inline UsdAttribute CreatePointsAttr() const
See GetPointsAttr(), 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
.
-
inline UsdAttribute GetVelocitiesAttr() const
If provided, ‘velocities’ should be used by renderers to.
compute positions between samples for the ‘points’ attribute, rather than interpolating between neighboring ‘points’ samples. This is the only reasonable means of computing motion blur for topologically varying PointBased primitives. It follows that the length of each ‘velocities’ sample must match the length of the corresponding ‘points’ sample. Velocity is measured in position units per second, as per most simulation software. To convert to position units per UsdTimeCode, divide by UsdStage::GetTimeCodesPerSecond().
See also UsdGeom_VelocityInterpolation .
Declaration
vector3f[] velocities
C++ Type
VtArray<GfVec3f>
Usd Type
SdfValueTypeNames->Vector3fArray
-
inline UsdAttribute CreateVelocitiesAttr() const
See GetVelocitiesAttr(), 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
.
-
inline UsdAttribute GetAccelerationsAttr() const
If provided, ‘accelerations’ should be used with velocities to compute positions between samples for the ‘points’ attribute rather than interpolating between neighboring ‘points’ samples. Acceleration is measured in position units per second-squared. To convert to position units per squared UsdTimeCode, divide by the square of UsdStage::GetTimeCodesPerSecond().
Declaration
vector3f[] accelerations
C++ Type
VtArray<GfVec3f>
Usd Type
SdfValueTypeNames->Vector3fArray
-
inline UsdAttribute CreateAccelerationsAttr() const
See GetAccelerationsAttr(), 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
.
-
inline UsdAttribute GetNormalsAttr() const
Provide an object-space orientation for individual points, which, depending on subclass, may define a surface, curve, or free points. Note that ‘normals’ should not be authored on any Mesh that is subdivided, since the subdivision algorithm will define its own normals. ‘normals’ is not a generic primvar, but the number of elements in this attribute will be determined by its ‘interpolation’. See SetNormalsInterpolation() . If ‘normals’ and ‘primvars:normals’ are both specified, the latter has precedence.
Declaration
normal3f[] normals
C++ Type
VtArray<GfVec3f>
Usd Type
SdfValueTypeNames->Normal3fArray
-
inline UsdAttribute CreateNormalsAttr() const
See GetNormalsAttr(), 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
.
-
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
-
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
.
-
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
-
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
.
-
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
-
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
.
-
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
-
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
.
-
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
-
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
.
-
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
.
-
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
-
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
.
-
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
-
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
.
-
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.
-
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
-
static inline UsdGeomNurbsPatch 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
-
static const UsdSchemaType schemaType = UsdSchemaType::ConcreteTyped
Compile time constant representing what kind of schema this class is.
See also
Protected Functions
-
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.