IFC (IFC4X3_ADD2) under development IfcHalfSpaceSolid Semantic definition

A half space solid divides the domain into two by a base surface. Normally, the base surface is a plane and divides the infinitive space into two and indicates the side of the half-space by agreeing or disagreeing to the normal of the plane.

Figure illustrates the definition of the IfcHalfSpaceSolid within a given coordinate system. The base surface is given by an unbounded plane, the red boundary is shown for visualization purposes only.

half space solid
Figure — Half space solid geometry

For a valid half space solid the surface shall divide the domain into exactly two subsets. Also, within the domain the surface shall be manifold and all surface normals shall point into the same subset.

Informal Propositions

  1. The base surface shall divide the domain into exactly two subsets. If the half space solid is of subtype boxed half space (IfcBoxedHalfSpace), the domain in question is that of the attribute enclosure. In all other cases the domain is all of space and the base surface shall be unbounded.
  2. The base surface shall be an unbounded surface (subtype of IfcElementarySurface). Entity inheritance Attributes

# Attribute Type Description
IfcRepresentationItem (2)
LayerAssignment SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems

Assignment 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.

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.

Click to show 2 hidden inherited attributes Click to hide 2 inherited attributes
IfcHalfSpaceSolid (3)
1 BaseSurface IfcSurface

Surface defining side of half space.

2 AgreementFlag IfcBoolean

The agreement flag is TRUE if the normal to the BaseSurface points away from the material of the IfcHalfSpaceSolid. Otherwise it is FALSE.

* Dim IfcDimensionCount

This attribute is formally derived.


The space dimensionality of this class, it is always 3

Table Formal representation

ENTITY IfcHalfSpaceSolid
 SUBTYPE OF (IfcGeometricRepresentationItem);
	BaseSurface : IfcSurface;
	AgreementFlag : IfcBoolean;
	 Dim : IfcDimensionCount := 3;
END_ENTITY; References

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Is this page difficult to understand? Let us know! Changelog IFC4

  • attribute AgreementFlag type, Changed from "boolean" to "IfcBoolean"