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IfcFacetedBrep

Definition from ISO/CD 10303-42:1992: A faceted brep (IfcFacetedBrep) 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 (IfcPolyLoop) 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. NOTE 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
ISSUE: See issue log for changes made in IFC Release 1.5.

Informal proposition:

  1. 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;

References (1):

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

Inheritance graph

ENTITY IfcFacetedBrep;
ENTITY IfcSolidModel;
DERIVE
Dim  :  IfcDimensionCount :=  3;
ENTITY IfcManifoldSolidBrep;
Outer  :  IfcClosedShell;
END_ENTITY;