IFC 4.3.x development

8.9.3.52 IfcPolyline

Change log

IFC4

additionswhere_rulesSameDim
deletionswhere_rulesWR41

8.9.3.52.1 Semantic definitions at the entity

The IfcPolyline is a bounded curve with only linear segments defined by a list of Cartesian points. If the first and the last Cartesian point in the list are identical, then the polyline is a closed curve, otherwise it is an open curve.

EXAMPLE  Figure 1 illustrates a bounded IfcPolyline and shows the parametric length of each segment and of the total polyline.

"polyline examples"

NOTE  Definition according to ISO/CD 10303-42:1992
A polyline is a bounded curve of n - 1 linear segments, defined by a list of n points, P~1~, P~2~ ... P~n~. The _i_th segment of the curve is parameterized as follows:

Image    for 1 ≤ in - 1 where i - 1 ≤ ui and with parametric range of 0 <≤ un - 1.

NOTE  Entity adapted from polyline in ISO 10303-42.

HISTORY  New entity in IFC1.0

8.9.3.52.1 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
IfcCurve
Dim INVALID The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve.
IfcBoundedCurve
IfcPolyline
1 Points LIST [2:?] OF IfcCartesianPoint The points defining the polyline.

8.9.3.52.2 Entity inheritance

dot_inheritance IfcPolyline IfcPolyline IfcBoundedCurve IfcBoundedCurve IfcPolyline->IfcBoundedCurve IfcBoundedCurve_children 4 more... IfcBoundedCurve_children->IfcBoundedCurve IfcCurve IfcCurve IfcBoundedCurve->IfcCurve IfcCurve_children 7 more... IfcCurve_children->IfcCurve IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcCurve->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.9.3.52.3 Formal representations

ENTITY IfcPolyline
 SUBTYPE OF (IfcBoundedCurve);
	Points : LIST [2:?] OF IfcCartesianPoint;
 WHERE
	SameDim : SIZEOF(QUERY(Temp <* Points | Temp.Dim <> Points[1].Dim)) = 0;
END_ENTITY;