IFC 4.3.x development

8.9.3.4 IfcAxis2PlacementLinear

Change log

IFC4X3_RC3

added

8.9.3.4.1 Semantic definitions at the entity

The IfcAxis2PlacementLinear provides location and orientation to place items in a three-dimensional space confined to the context of a curve. Relative placement axes (Axis and RefDirection) are relative to the curve used for linear referencing provided in IfcPlacement Location (IfcPointByDistanceExpression BasisCurve), maintaining the relationship to the tangent of the curve.

8.9.3.4.1 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
IfcPlacement
1 Location IfcPoint The geometric position of a reference point, such as the center of a circle, of the item to be located.
Dim INVALID The space dimensionality of this class, derived from the dimensionality of the location.
IfcAxis2PlacementLinear
2 Axis OPTIONAL IfcDirection The exact direction of the local Z Axis.
3 RefDirection OPTIONAL IfcDirection The direction used to determine the direction of the local X Axis. In case both Axis and RefDirection are set and not perpendicular an adjustment is necessary to maintain orthogonality to the Axis direction. If RefDirection is omitted, the direction is taken from the curve tangent at Location.

8.9.3.4.2 Entity inheritance

dot_inheritance IfcAxis2PlacementLinear IfcAxis2PlacementLinear IfcPlacement IfcPlacement IfcAxis2PlacementLinear->IfcPlacement IfcPlacement_children 3 more... IfcPlacement_children->IfcPlacement IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcPlacement->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.9.3.4.3 Formal representations

ENTITY IfcAxis2PlacementLinear
 SUBTYPE OF (IfcPlacement);
	Axis : OPTIONAL IfcDirection;
	RefDirection : OPTIONAL IfcDirection;
 WHERE
	WR1 : 'IFC4X3_DEV_a1492713.IFCPOINTBYDISTANCEEXPRESSION' IN TYPEOF(SELF\IfcPlacement.Location);
	WR2 : (NOT (EXISTS (Axis))) OR (NOT (EXISTS (RefDirection))) OR (IfcCrossProduct(Axis,RefDirection).Magnitude > 0.0);
END_ENTITY;