add pointWeights attribute to NurbsCurves in usdGeom

Fixes #1554

(Internal change: 2261283)

pxr/usd/usdGeom/generatedSchema.usda

@@ -2997,6 +2997,14 @@ class NurbsCurves "NurbsCurves" (
         doc = """The primary geometry attribute for all PointBased
         primitives, describes points in (local) space."""
     )
+    double[] pointWeights (
+        doc = """Optionally provides \"w\" components for each control point,
+        thus must be the same length as the points attribute.  If authored,
+        the curve will be rational.  If unauthored, the curve will be
+        polynomial, i.e. weight for all points is 1.0.
+        \\note Some DCC's pre-weight the points, but in this schema, 
+        points are not pre-weighted."""
+    )
     color3f[] primvars:displayColor (
         doc = '''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

pxr/usd/usdGeom/nurbsCurves.cpp

@@ -154,6 +154,23 @@ UsdGeomNurbsCurves::CreateRangesAttr(VtValue const &defaultValue, bool writeSpar
                        writeSparsely);
 }
 
+UsdAttribute
+UsdGeomNurbsCurves::GetPointWeightsAttr() const
+{
+    return GetPrim().GetAttribute(UsdGeomTokens->pointWeights);
+}
+
+UsdAttribute
+UsdGeomNurbsCurves::CreatePointWeightsAttr(VtValue const &defaultValue, bool writeSparsely) const
+{
+    return UsdSchemaBase::_CreateAttr(UsdGeomTokens->pointWeights,
+                       SdfValueTypeNames->DoubleArray,
+                       /* custom = */ false,
+                       SdfVariabilityVarying,
+                       defaultValue,
+                       writeSparsely);
+}
+
 namespace {
 static inline TfTokenVector
 _ConcatenateAttributeNames(const TfTokenVector& left,const TfTokenVector& right)
@@ -174,6 +191,7 @@ UsdGeomNurbsCurves::GetSchemaAttributeNames(bool includeInherited)
         UsdGeomTokens->order,
         UsdGeomTokens->knots,
         UsdGeomTokens->ranges,
+        UsdGeomTokens->pointWeights,
     };
     static TfTokenVector allNames =
         _ConcatenateAttributeNames(

pxr/usd/usdGeom/nurbsCurves.h

@@ -245,6 +245,33 @@ class UsdGeomNurbsCurves : public UsdGeomCurves
     USDGEOM_API
     UsdAttribute CreateRangesAttr(VtValue const &defaultValue = VtValue(), bool writeSparsely=false) const;
 
+public:
+    // --------------------------------------------------------------------- //
+    // POINTWEIGHTS 
+    // --------------------------------------------------------------------- //
+    /// Optionally provides "w" components for each control point,
+    /// thus must be the same length as the points attribute.  If authored,
+    /// the curve will be rational.  If unauthored, the curve will be
+    /// polynomial, i.e. weight for all points is 1.0.
+    /// \note Some DCC's pre-weight the \em points, but in this schema, 
+    /// \em points are not pre-weighted.
+    ///
+    /// | ||
+    /// | -- | -- |
+    /// | Declaration | `double[] pointWeights` |
+    /// | C++ Type | VtArray<double> |
+    /// | \ref Usd_Datatypes "Usd Type" | SdfValueTypeNames->DoubleArray |
+    USDGEOM_API
+    UsdAttribute GetPointWeightsAttr() const;
+
+    /// See GetPointWeightsAttr(), and also 
+    /// \ref Usd_Create_Or_Get_Property for when to use Get vs Create.
+    /// If specified, author \p defaultValue as the attribute's default,
+    /// sparsely (when it makes sense to do so) if \p writeSparsely is \c true -
+    /// the default for \p writeSparsely is \c false.
+    USDGEOM_API
+    UsdAttribute CreatePointWeightsAttr(VtValue const &defaultValue = VtValue(), bool writeSparsely=false) const;
+
 public:
     // ===================================================================== //
     // Feel free to add custom code below this line, it will be preserved by 

pxr/usd/usdGeom/schema.usda

@@ -1678,6 +1678,15 @@ class NurbsCurves "NurbsCurves" (
         knots['i'th curve slice][order[i]-1]. The maxium must be less 
         than or equal to the last element's value in knots['i'th curve slice].
 	Range maps to (vmin, vmax) in the RenderMan spec.""")
+
+    double[] pointWeights (
+        doc = """Optionally provides "w" components for each control point,
+        thus must be the same length as the points attribute.  If authored,
+        the curve will be rational.  If unauthored, the curve will be
+        polynomial, i.e. weight for all points is 1.0.
+        \\note Some DCC's pre-weight the \\em points, but in this schema, 
+        \\em points are not pre-weighted."""
+    )
 }
 
 class Points "Points" (

pxr/usd/usdGeom/testenv/testUsdGeomCurves.py

@@ -68,6 +68,7 @@ def test_schema(self):
         assert 'curveVertexCounts' in self.schema.GetSchemaAttributeNames()
         assert 'knots' in self.schema.GetSchemaAttributeNames()
         assert 'order' in self.schema.GetSchemaAttributeNames()
+        assert 'pointWeights' in self.schema.GetSchemaAttributeNames()
         knots = self.schema.GetKnotsAttr()
         assert(knots)
 

pxr/usd/usdGeom/tokens.h

@@ -464,7 +464,7 @@ struct UsdGeomTokensType {
     const TfToken points;
     /// \brief "pointWeights"
     /// 
-    /// UsdGeomNurbsPatch
+    /// UsdGeomNurbsPatch, UsdGeomNurbsCurves
     const TfToken pointWeights;
     /// \brief "positions"
     /// 

pxr/usd/usdGeom/wrapNurbsCurves.cpp

@@ -69,6 +69,13 @@ _CreateRangesAttr(UsdGeomNurbsCurves &self,
     return self.CreateRangesAttr(
         UsdPythonToSdfType(defaultVal, SdfValueTypeNames->Double2Array), writeSparsely);
 }
+
+static UsdAttribute
+_CreatePointWeightsAttr(UsdGeomNurbsCurves &self,
+                                      object defaultVal, bool writeSparsely) {
+    return self.CreatePointWeightsAttr(
+        UsdPythonToSdfType(defaultVal, SdfValueTypeNames->DoubleArray), writeSparsely);
+}
 
 static std::string
 _Repr(const UsdGeomNurbsCurves &self)
@@ -132,6 +139,13 @@ void wrapUsdGeomNurbsCurves()
              &_CreateRangesAttr,
              (arg("defaultValue")=object(),
               arg("writeSparsely")=false))
+
+        .def("GetPointWeightsAttr",
+             &This::GetPointWeightsAttr)
+        .def("CreatePointWeightsAttr",
+             &_CreatePointWeightsAttr,
+             (arg("defaultValue")=object(),
+              arg("writeSparsely")=false))
 
         .def("__repr__", ::_Repr)
     ;
@@ -163,4 +177,4 @@ namespace {
 WRAP_CUSTOM {
 }
 
-} // anonymous namespace
+}