IFC 4.3.x development

8.9.3.27 IfcCurveBoundedPlane

8.9.3.27.1 Semantic definitions at the entity

The IfcCurveBoundedPlane is a parametric planar surface with curved boundaries defined by one or more boundary curves. The bounded plane is defined to be the portion of the basis surface in the direction of N x T from any point on the boundary, where N is the surface normal and T the boundary curve tangent vector at this point. The region so defined shall be arcwise connected.

The BasisSurface is an IfcPlane that establishes the position coordinate system by SELF\IfcElementarySurface.Position. The OuterBoundary and the InnerBoundaries (if provided) shall lie on the surface of IfcPlane. The outer and inner boundary curves shall be defined using the u, and v values provided by parameterization of the BasisSurface as their x, and y coordinate values.

NOTE  Entity defined in analogy to curve_bounded_surface defined in ISO 10303-42.

HISTORY  New entity in IFC1.5

IFC2x CHANGE  The data type of the attribute OuterBoundary and InnerBoundaries has been changed from Ifc2DCompositeCurve to supertype IfcCurve.

8.9.3.27.1 Attributes

# Attribute Type Description
IfcRepresentationItem
LayerAssignmentSET [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.
IfcBoundedSurface
IfcCurveBoundedPlane
1 BasisSurface IfcPlane The surface to be bound.
2 OuterBoundary IfcCurve The outer boundary of the surface.
3 InnerBoundariesSET [0:?] OF IfcCurve An optional set of inner boundaries. They shall not intersect each other or the outer boundary.

8.9.3.27.2 Entity inheritance

dot_inheritance IfcCurveBoundedPlane IfcCurveBoundedPlane IfcBoundedSurface IfcBoundedSurface IfcCurveBoundedPlane->IfcBoundedSurface IfcBoundedSurface_children 3 more... IfcBoundedSurface_children->IfcBoundedSurface IfcSurface IfcSurface IfcBoundedSurface->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

8.9.3.27.3 Formal representations

ENTITY IfcCurveBoundedPlane
 SUBTYPE OF (IfcBoundedSurface);
	BasisSurface : IfcPlane;
	OuterBoundary : IfcCurve;
	InnerBoundaries : SET [0:?] OF IfcCurve;
END_ENTITY;