IfcFacetedBrep

Semantic definitions at the entity

Entity definition

Definition from ISO/CD 10303-42:1992: A faceted brep is a simple form of boundary representation model in which all faces are planar and all edges are straight lines. Unlike the B-rep model, edges and vertices are not represented explicitly in the model but are implicitly available through the poly loop entity. A faceted B-rep has to meet the same topological constraints as the manifold solid Brep.

NOTE: The faceted brep has been introduced in order to support the larger number of systems that allow boundary type solid representations with planar surfaces only.

NOTE: Corresponding STEP entity: faceted_brep. Please refer to ISO/IS 10303-42:1994, p. 173 for the final definition of the formal standard. In the current IFC Release faceted B-rep with voids is represented by an own subtype and not defined via an implicit ANDOR supertype constraint as in ISO/IS 10303-42:1994. This change has been made due to the fact, that only ONEOF supertype constraint is allowed within the IFC object model.
HISTORY New class in IFC Release 1.0

Informal proposition:

All the bounding loops of all the faces of all the shells in the IfcFacetedBrep shall be of type IfcPolyLoop.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	A
IfcRepresentationItem
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
IfcFacetedBrep

Formal representations

XSD Specification

 <xs:element name="IfcFacetedBrep" type="ifc:IfcFacetedBrep" substitutionGroup="ifc:IfcManifoldSolidBrep" nillable="true"/>

 <xs:complexType name="IfcFacetedBrep">

  <xs:complexContent>

   <xs:extension base="ifc:IfcManifoldSolidBrep"/>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcFacetedBrep

 SUBTYPE OF (IfcManifoldSolidBrep);

END_ENTITY;

 EXPRESS-G diagram