IFC 4.3.x development

8.9.3.28 IfcCurveSegment

Change log

IFC4X3_RC3

added

8.9.3.28.1 Semantic definitions at the entity

A type of segment positioned along a curve cutting a segment from the parent curve. The positioning curve (StartPlacement.PlacementMeasuredAlong) does not neccessarly correspond with the ParentCurve.

8.9.3.28.1 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
IfcSegment
1 Transition IfcTransitionCode Connectivity between the continuous segments is not enforced per se to be tangential. Setting "TangentialContinuity" to True means that the current segment shall continue with tangential continuity to the previous one.
UsingCurves SET [1:?] OF IfcCompositeCurve FOR Segments The set of composite curves which use this composite curve segment as a segment. This set shall not be empty.
IfcCurveSegment
2 Placement IfcPlacement Placement in the context of the curve using this segment. As insertion point SegmentStart is the reference point of Placement. RefDirection of Placement also specifies the sense of the trimmed segment of ParentCurve. RefDirection is bound to the paramettrization sense of the segment.
3 SegmentStart IfcCurveMeasureSelect First trimming point of the curve segment on the ParentCurve. This point is used as the insertion point into the segmented, gradient or composite curve using this segment.
4 SegmentLength IfcCurveMeasureSelect Length of segment measured as length or parameter value from SegmentStart. The sign of this value defines the sense agreement.
5 ParentCurve IfcCurve Curve to be used as base for the segment definition.
Dim INVALID The space dimensionality of this class, defined by the dimensionality of the first ParentCurve.

8.9.3.28.2 Entity inheritance

dot_inheritance IfcCurveSegment IfcCurveSegment IfcSegment IfcSegment IfcCurveSegment->IfcSegment IfcCompositeCurveSegment IfcCompositeCurveSegment IfcCompositeCurveSegment->IfcSegment IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcSegment->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.9.3.28.3 Formal representations

ENTITY IfcCurveSegment
 SUBTYPE OF (IfcSegment);
	Placement : IfcPlacement;
	SegmentStart : IfcCurveMeasureSelect;
	SegmentLength : IfcCurveMeasureSelect;
	ParentCurve : IfcCurve;
 DERIVE
	 Dim : IfcDimensionCount := ParentCurve.Dim;
END_ENTITY;