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 entity in IFC Release 1.0

Informal propositions:

Each void shell shall be disjoint from the outer shell and from every other void shell
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
Each shell in the IfcManifoldSolidBrep shall be referenced only once.
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.

Inheritance graph

ENTITY IfcFacetedBrepWithVoids;

ENTITY IfcRepresentationItem;

INVERSE

LayerAssignments

SET OF IfcPresentationLayerAssignment FOR AssignedItems;

StyledByItem

SET [0:1] OF IfcStyledItem FOR Item;

ENTITY IfcGeometricRepresentationItem;

ENTITY IfcSolidModel;

DERIVE

Dim

IfcDimensionCount := 3;

ENTITY IfcManifoldSolidBrep;

Outer

IfcClosedShell;

ENTITY IfcFacetedBrepWithVoids;

Voids

SET [1:?] OF IfcClosedShell;

END_ENTITY;