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IfcFacetedBrepWithVoids

Definition from IAI: The IfcFacetedBrepWithVoids is a specialization of a faceted 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 Corresponding STEP entity: brep_with_voids (see note above). Please refer to ISO/IS 10303-42:1994, p. 173 for the final definition of the formal standard. In IFC faceted B-rep with voids is represented by this subtype IfcFacetedBrepWithVoids and not defined via an implicit ANDOR supertype constraint as in ISO/IS 10303-42:1994 between an instance of faceted_brep AND brep_with_voids. 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 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 bounding loops of all the faces of all the shells in the IfcFacetedBrep shall be of type IfcPolyLoop.

EXPRESS specification:

ENTITY IfcFacetedBrepWithVoids
SUBTYPE OF ( IfcManifoldSolidBrep);
Voids  :  SET [1:?] OF IfcClosedShell;
END_ENTITY;

Attribute definitions:

Voids  :  Set of closed shells defining voids within the solid.

References (1):

Name Type Referred through Express-G
IfcManifoldSolidBrep Entity
Subtype
Diagram 4

Inheritance graph

ENTITY IfcFacetedBrepWithVoids;
ENTITY IfcSolidModel;
DERIVE
Dim  :  IfcDimensionCount :=  3;
ENTITY IfcManifoldSolidBrep;
Outer  :  IfcClosedShell;
ENTITY IfcFacetedBrepWithVoids;
Voids  :  SET [1:?] OF IfcClosedShell;
END_ENTITY;