Represent Faceted Brep Solid Model

Overview

Identifies the information requirements for provision of a 3D faceted boundary representation solid model shape.
A faceted boundary representation solid model is a simplified form of boundary representation solid model in which all faces are planar and all edges are straight lines. The outer boundary of the solid model shape is determined by a closed shell.
Voids may be allowed in a solid model representation. A void is defined as a closed shell within the boundary of the solid model. Voids within the solid model may not overlap.
A shell is defined as a subtype of a connected face set which in turn comprises a set of faces. The connected face set must be defined.

Results

A 3D faceted boundary representation solid model (with or without voids) is defined.

Description	Entity/Pset/Functional Part	MAN	REC	OPT
Determine the faces to be used in the solid model and bring them into a connected face set. Note that where the representation is to be a faceted Brep with voids, a connected face set should be determined for the outer shell and for each shell that is to be a void. Assign any surfaces that are required within the connected face set.	fp_connected_face_set
Connected face sets are defined by the subtype closed shell within a faceted Brep solid model.The faces of the connected face set therefore must be reassigned to the appropriate subtype.	IfcClosedShell.CfsFaces
Assign the closed shells that is to be the outer shell of the solid model.	IfcFacetedBrep.Outer IfcFacetedBrepWithVoids.Outer
IF the solid model is to be represented as a faceted Brep with voids Assign the set of shells that are to form the voids in the solid model
Ensure that the solid model is defined as 3 dimensional by setting the value of the dimensioning attribute to 3	IfcFacetedBrep.Dim IfcFacetedBrepWithVoids.Dim

IFC Entities Required

• IfcClosedShell
• IfcFacetedBrep
• IfcFacetedBrepWithVoids
• IfcManifoldSolidBrep

IFC Datatypes Required

• -

IFC Functions Required

• -

IDM Functional Parts Required

• fp_connect_face_set

EXPRESS-G

Overview of Surface and Faceted Brep Solid Models

EXPRESS Schema

SCHEMA FP_REPRESENT_FACETED_BREP_SOLID_MODEL;

  ENTITY IfcClosedShell
    SUBTYPE OF(fp_connect_face_set);
  END_ENTITY;

  ENTITY IfcManifoldSolidBrep
    ABSTRACT SUPERTYPE OF (ONEOF(IfcFacetedBrep, IfcFacetedBrepWithVoids));
      Outer : IfcClosedShell;
  END_ENTITY;

  ENTITY IfcFacetedBrep
    SUBTYPE OF(IfcManifoldSolidBrep);
  END_ENTITY;

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

  ENTITY fp_connect_face_set;
  END_ENTITY;

END_