IfcAdvancedBrepWithVoids

ifcadvancedbrewwithvoids是高级B-rep的一个专门化，它的内部包含一个或多个空隙。空隙被表示为闭合壳，这些壳被定义为使壳法线指向空洞。

注：实体改编自ISO 10303-42中定义的高级形状表示法。

IFC4中增加的新实体

非正式提议：

①每个空壳应与外壳和其他空壳分离

②每个空心外壳应封闭在外壳内，而不是任何其他空心外壳内。尤其是外壳不在空壳组中

③IfcManifoldSolidBrep中的每个shell只能引用一次。

④IfcAdvancedBrep和IfcA中所有外壳的所有面AdvancedBrepwithvoids.空隙应为IfcAdvancedFace类型。

Formal Propositions

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

 

 

 

 

 

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

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;