 | Bézier-Spline-Fläche mit (gegebenen) Kontrollpunkten |
 | BSpline Surface With Knots |
| Item | SPF | XML | Change | Description | IFC2x3 to IFC4 4.0.0.0 |
|---|---|---|---|---|
| IfcBSplineSurfaceWithKnots | ADDED | IFC4 Addendum 1 4.0.1.0 | ||
| IfcBSplineSurfaceWithKnots | ||||
| UDegree | MODIFIED | Type changed from INTEGER to IfcInteger. | ||
| VDegree | MODIFIED | Type changed from INTEGER to IfcInteger. | ||
| UClosed | MODIFIED | Type changed from LOGICAL to IfcLogical. | ||
| VClosed | MODIFIED | Type changed from LOGICAL to IfcLogical. | ||
| SelfIntersect | MODIFIED | Type changed from LOGICAL to IfcLogical. | ||
| UMultiplicities | MODIFIED | Type changed from INTEGER to IfcInteger. | ||
| VMultiplicities | MODIFIED | Type changed from INTEGER to IfcInteger. |
The IfcBSplineSurfaceWithKnots is a general form of rational or polynomial parametric surface in which the knot values are explicitly given.
NOTE Definition according to ISO/CD 10303-42:1992
This is a B-spline surface in which the knot values are explicitly given. This subtype shall be used to represent non-uniform B-spline surfaces, and may also be used for other knot types.
All knot multiplicities except the first and the last shall be in the range 1,....,d; the first and last may have a maximum value of d + 1. In evaluating the basis functions, a knot u of, e.g., multiplicity 3 is interpreted as a sequence u, u, u, in the knot array.
NOTE Entity adapted from b_spline_surface_with_knots defined in ISO10303-42.
HISTORY New entity in IFC4.
| # | Attribute | Type | Cardinality | Description | G |
|---|---|---|---|---|---|
| 8 | UMultiplicities | IfcInteger | L[2:?] | The multiplicities of the knots in the u parameter direction. | X |
| 9 | VMultiplicities | IfcInteger | L[2:?] | The multiplicities of the knots in the v parameter direction. | X |
| 10 | UKnots | IfcParameterValue | L[2:?] | The list of the distinct knots in the u parameter direction. | X |
| 11 | VKnots | IfcParameterValue | L[2:?] | The list of the distinct knots in the v parameter direction. | X |
| 12 | KnotSpec | IfcKnotType | The description of the knot type. | X | |
| KnotVUpper :=SIZEOF(VKnots) | IfcInteger | The number of distinct knots in the v parameter direction. | X | ||
| KnotUUpper :=SIZEOF(UKnots) | IfcInteger | The number of distinct knots in the u parameter direction. | X |
| Rule | Description |
|---|---|
| UDirectionConstraints | The function returns TRUE when the parameter constraints are verified for the u direction. |
| VDirectionConstraints | The function returns TRUE when the parameter constraints are verified for the v direction. |
| CorrespondingULists | The number of UMultiplicities shall be the same as the number of UKnots. |
| CorrespondingVLists | The number of VMultiplicities shall be the same as the number of VKnots. |
| # | Attribute | Type | Cardinality | Description | G |
|---|---|---|---|---|---|
| IfcRepresentationItem | |||||
| LayerAssignment | IfcPresentationLayerAssignment @AssignedItems | S[0:1] | Assignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.
IFC2x3 CHANGE The inverse attribute LayerAssignments has been added. IFC4 CHANGE The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed. | X | |
| StyledByItem | IfcStyledItem @Item | S[0:1] | Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.
IFC2x3 CHANGE The inverse attribute StyledByItem has been added. | X | |
| IfcGeometricRepresentationItem | |||||
| IfcSurface | |||||
| Dim :=3 | IfcDimensionCount | The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item.
IFC4 CHANGE Derived attribute promoted from subtypes. |
X | ||
| IfcBoundedSurface | |||||
| IfcBSplineSurface | |||||
| 1 | UDegree | IfcInteger | Algebraic degree of basis functions in u. | X | |
| 2 | VDegree | IfcInteger | Algebraic degree of basis functions in v. | X | |
| 3 | ControlPointsList | IfcCartesianPoint | L[2:?] L[2:?] | This is a list of lists of control points. | X |
| 4 | SurfaceForm | IfcBSplineSurfaceForm | Indicator of special surface types. | X | |
| 5 | UClosed | IfcLogical | Indication of whether the surface is closed in the u direction; this is for information only. | X | |
| 6 | VClosed | IfcLogical | Indication of whether the surface is closed in the v direction; this is for information only. | X | |
| 7 | SelfIntersect | IfcLogical | Flag to indicate whether, or not, surface is self-intersecting; this is for information only. | X | |
| UUpper :=SIZEOF(ControlPointsList) - 1 | IfcInteger | Upper index on control points in u direction. | X | ||
| VUpper :=SIZEOF(ControlPointsList[1]) - 1 | IfcInteger | Upper index on control points in v direction. | X | ||
| ControlPoints :=IfcMakeArrayOfArray(ControlPointsList, 0,UUpper,0,VUpper) | IfcCartesianPoint | A[0:UUpper] A[0:VUpper] | Array (two-dimensional) of control points defining surface geometry. This array is constructed from the control points list. | X | |
| IfcBSplineSurfaceWithKnots | |||||
| 8 | UMultiplicities | IfcInteger | L[2:?] | The multiplicities of the knots in the u parameter direction. | X |
| 9 | VMultiplicities | IfcInteger | L[2:?] | The multiplicities of the knots in the v parameter direction. | X |
| 10 | UKnots | IfcParameterValue | L[2:?] | The list of the distinct knots in the u parameter direction. | X |
| 11 | VKnots | IfcParameterValue | L[2:?] | The list of the distinct knots in the v parameter direction. | X |
| 12 | KnotSpec | IfcKnotType | The description of the knot type. | X | |
| KnotVUpper :=SIZEOF(VKnots) | IfcInteger | The number of distinct knots in the v parameter direction. | X | ||
| KnotUUpper :=SIZEOF(UKnots) | IfcInteger | The number of distinct knots in the u parameter direction. | X | ||
<xs:element name="IfcBSplineSurfaceWithKnots" type="ifc:IfcBSplineSurfaceWithKnots" substitutionGroup="ifc:IfcBSplineSurface" nillable="true"/>
<xs:complexType name="IfcBSplineSurfaceWithKnots">
<xs:complexContent>
<xs:extension base="ifc:IfcBSplineSurface">
<xs:attribute name="UMultiplicities" use="optional">
<xs:simpleType>
<xs:restriction>
<xs:simpleType>
<xs:list itemType="ifc:IfcInteger"/>
</xs:simpleType>
<xs:minLength value="2"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="VMultiplicities" use="optional">
<xs:simpleType>
<xs:restriction>
<xs:simpleType>
<xs:list itemType="ifc:IfcInteger"/>
</xs:simpleType>
<xs:minLength value="2"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="UKnots" use="optional">
<xs:simpleType>
<xs:restriction>
<xs:simpleType>
<xs:list itemType="ifc:IfcParameterValue"/>
</xs:simpleType>
<xs:minLength value="2"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="VKnots" use="optional">
<xs:simpleType>
<xs:restriction>
<xs:simpleType>
<xs:list itemType="ifc:IfcParameterValue"/>
</xs:simpleType>
<xs:minLength value="2"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="KnotSpec" type="ifc:IfcKnotType" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
ENTITY IfcBSplineSurfaceWithKnots
SUPERTYPE OF(IfcRationalBSplineSurfaceWithKnots)
SUBTYPE OF (IfcBSplineSurface);
UMultiplicities : LIST [2:?] OF IfcInteger;
VMultiplicities : LIST [2:?] OF IfcInteger;
UKnots : LIST [2:?] OF IfcParameterValue;
VKnots : LIST [2:?] OF IfcParameterValue;
KnotSpec : IfcKnotType;
DERIVE
KnotVUpper : IfcInteger := SIZEOF(VKnots);
KnotUUpper : IfcInteger := SIZEOF(UKnots);
WHERE
UDirectionConstraints : IfcConstraintsParamBSpline (
SELF\IfcBSplineSurface.UDegree, KnotUUpper,
SELF\IfcBSplineSurface.UUpper, UMultiplicities, UKnots);
VDirectionConstraints : IfcConstraintsParamBSpline (
SELF\IfcBSplineSurface.VDegree, KnotVUpper,
SELF\IfcBSplineSurface.VUpper, VMultiplicities, VKnots);
CorrespondingULists : SIZEOF(UMultiplicities) = KnotUUpper;
CorrespondingVLists : SIZEOF(VMultiplicities) = KnotVUpper;
END_ENTITY;
EXPRESS-G diagram
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