IfcAdvancedBrepWithVoids

BACnet MVD

#### IfcAdvancedBrepWithVoids

Natural language names

| Boundary Representation mit Aussparungen - NURBS
| Advanced Brep With Voids
| Représentation frontière avancée avec trous

Change log

Item | SPF | XML | Change | Description
--- | --- | --- | --- | ---
IFC2x3 to IFC4
IfcAdvancedBrepWithVoids |  |  | ADDED |

##### Semantic definitions at the entity

Entity definition

The IfcAdvancedBrepWithVoids is a specialization of an advanced B-rep which contains one or more voids in its interior. The voids are represented as closed shells which are defined so that the shell normal point into the void.

> NOTE Entity adapted from advanced_brep_shape_representation defined in ISO 10303-42.

> HISTORY New entity in IFC4

Informal Propositions:

1. Each void shell shall be disjoint from the outer shell and from every other void shell
2. Each void shell shall be enclosed within the outer shell but not within any other void shell. In particular the outer shell is not in the set of void shells
3. Each shell in the IfcManifoldSolidBrep shall be referenced only once.
4. All the faces of all the shells in the IfcAdvancedBrep and the IfcAdvancedBrepWithVoids.Voids shall be of type IfcAdvancedFace.

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
2 | Voids | IfcClosedShell | S[1:?] |  |  | X

Formal Propositions

Rule | Description
--- | ---
VoidsHaveAdvancedFaces | Each face of the voids within the advanced B-rep with voids shall be of type IfcAdvancedFace.

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
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

X

IfcGeometricRepresentationItem
IfcSolidModel
| Dim :=3 | IfcDimensionCount |  | The space dimensionality of this class, it is always 3. | X | X
IfcManifoldSolidBrep
1 | Outer | IfcClosedShell |  | A closed shell defining the exterior boundary of the solid. The shell normal shall point away from the interior of the solid. | X | X
IfcAdvancedBrep
IfcAdvancedBrepWithVoids
2 | Voids | IfcClosedShell | S[1:?] |  |  | X

##### Formal representations

XML Specification
`<xs:element name="IfcAdvancedBrepWithVoids" type="ifc:IfcAdvancedBrepWithVoids" substitutionGroup="ifc:IfcAdvancedBrep" nillable="true"/>
<xs:complexType name="IfcAdvancedBrepWithVoids">
<xs:complexContent>
<xs:extension base="ifc:IfcAdvancedBrep">
<xs:sequence>
<xs:element name="Voids">
<xs:complexType>
<xs:sequence>
<xs:element ref="ifc:IfcClosedShell" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute ref="ifc:itemType" fixed="ifc:IfcClosedShell"/>
<xs:attribute ref="ifc:cType" fixed="set"/>
<xs:attribute ref="ifc:arraySize" use="optional"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcAdvancedBrepWithVoids
SUBTYPE OF (IfcAdvancedBrep);
Voids : SET [1:?] OF IfcClosedShell;
WHERE
VoidsHaveAdvancedFaces : SIZEOF (QUERY (Vsh <* Voids |
SIZEOF (QUERY (Afs <* Vsh.CfsFaces |
(NOT ('IFCTOPOLOGYRESOURCE.IfcAdvancedFace' IN TYPEOF(Afs)))
)) = 0
)) = 0;
END_ENTITY;

EXPRESS-G diagram

`

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