IfcFacetedBrep

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.

EXPRESS specification:

ENTITY IfcFacetedBrep

SUBTYPE OF (

IfcManifoldSolidBrep);

END_ENTITY;

Inheritance graph

ENTITY IfcFacetedBrep;

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 IfcFacetedBrep;

END_ENTITY;