IFC 4.3.x development

8.9.3.70 IfcSurfaceOfLinearExtrusion

Change log

IFC4

additionswhere_rulesDepthGreaterZero
deletionswhere_rulesWR41

8.9.3.70.1 Semantic definitions at the entity

The IfcSurfaceOfLinearExtrusion is a surface derived by sweeping a curve along a vector.

NOTE  Definition according to ISO/CD 10303-42:1992
This surface is a simple swept surface or a generalized cylinder obtained by sweeping a curve in a given direction. The parameterization is as follows where the curve has a parameterization λ(u):

V = ExtrusionAxis

Image The parameterization range for v is -∞ < v < ∞ and for u it is defined by the curve parameterization.

NOTE  Entity adapted from surface_of_linear_extrusion defined in ISO 10303-42.

HISTORY  New entity in IFC2x.

Informal Propositions:

  1. The surface shall not self-intersect

8.9.3.70.1 Attributes

# Attribute Type Description
IfcRepresentationItem
LayerAssignment SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItemsAssignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.

> IFC2x3 CHANGE  The inverse attribute LayerAssignments has been added.

> IFC4 CHANGE  The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed.
StyledByItem SET [0:1] OF IfcStyledItem FOR Item Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.



> IFC2x3 CHANGE  The inverse attribute StyledByItem has been added.
IfcGeometricRepresentationItem
IfcSurface
Dim INVALID The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item.

> IFC4 CHANGE Derived attribute promoted from subtypes.
IfcSweptSurface
1 SweptCurve IfcProfileDef The curve to be swept in defining the surface. The curve is defined as a profile within the position coordinate system.
2 Position OPTIONAL IfcAxis2Placement3D Position coordinate system for the swept surface, provided by a profile definition within the XY plane of the Position coordinates. If not provided, the position of the profile being swept is determined by the object coordinate system. In this case, the swept surface is not repositioned.

> IFC4 CHANGE  The attribute has been changed to OPTIONAL with upward compatibility for file-based exchange.
IfcSurfaceOfLinearExtrusion
3 ExtrudedDirectionIfcDirection The direction of the extrusion.
4 Depth IfcLengthMeasure The depth of the extrusion, it determines the parameterization.
ExtrusionAxis INVALID The extrusion axis defined as vector.

8.9.3.70.2 Entity inheritance

dot_inheritance IfcSurfaceOfLinearExtrusion IfcSurfaceOfLinearExtrusion IfcSweptSurface IfcSweptSurface IfcSurfaceOfLinearExtrusion->IfcSweptSurface IfcSurfaceOfRevolution IfcSurfaceOfRevolution IfcSurfaceOfRevolution->IfcSweptSurface IfcSurface IfcSurface IfcSweptSurface->IfcSurface IfcSurface_children 3 more... IfcSurface_children->IfcSurface IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcSurface->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.9.3.70.3 Formal representations

ENTITY IfcSurfaceOfLinearExtrusion
 SUBTYPE OF (IfcSweptSurface);
	ExtrudedDirection : IfcDirection;
	Depth : IfcLengthMeasure;
 DERIVE
	 ExtrusionAxis : IfcVector := IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcVector (ExtrudedDirection, Depth);
 WHERE
	DepthGreaterZero : Depth > 0.;
END_ENTITY;