8.9.3.2 IfcAxis2Placement2D

8.9.3.2.1 Semantic definition

The IfcAxis2Placement2D provides location and orientation to place items in a two-dimensional space. The attribute RefDirection defines the x axis, the y axis is derived. If the attribute RefDirection is not given, the placement defaults to P[1] (x-axis) as [1.,0.] and P[2] (y-axis) as [0.,1.].

Figure 8.9.3.2.A illustrates the definition of the IfcAxis2Placement2D within the two-dimensional coordinate system.

8.9.3.2.2 Entity inheritance

8.9.3.2.3 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. 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.
IfcPlacement (2)
1	Location	IfcPoint	The geometric position of a reference point, such as the center of a circle, of the item to be located.
*	Dim	IfcDimensionCount	This attribute is formally derived. `Location.Dim` The space dimensionality of this class, derived from the dimensionality of the location.
Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes
IfcAxis2Placement2D (2)
2	RefDirection	OPTIONAL IfcDirection	The direction used to determine the direction of the local X axis. If a value is omitted that it defaults to [1.0, 0.0.].
*	P	LIST [2:2] OF IfcDirection	This attribute is formally derived. `IfcBuild2Axes(RefDirection)` P[1]: The normalized direction of the placement X Axis. This is [1.0,0.0] if RefDirection is omitted. P[2]: The normalized direction of the placement Y Axis. This is a derived attribute and is orthogonal to P[1]. If RefDirection is omitted, it defaults to [0.0,1.0]

Table 8.9.3.2.C

8.9.3.2.4 Formal propositions

Name	Description
LocationIs2D	No description available.
`SELF\IfcPlacement.Location.Dim = 2`
LocationIsCP	No description available.
`'IFC4X3.IFCCARTESIANPOINT' IN TYPEOF(SELF\IfcPlacement.Location)`
RefDirIs2D	No description available.
`(NOT (EXISTS (RefDirection))) OR (RefDirection.Dim = 2)`

Table 8.9.3.2.D

8.9.3.2.5 Examples

Figure 8.9.3.2.B

LinearPlacement_2

8.9.3.2.6 Formal representation

ENTITY IfcAxis2Placement2D
 SUBTYPE OF (IfcPlacement);
	RefDirection : OPTIONAL IfcDirection;
 DERIVE
	 P : LIST [2:2] OF IfcDirection := IfcBuild2Axes(RefDirection);
 WHERE
	LocationIs2D : SELF\IfcPlacement.Location.Dim = 2;
	LocationIsCP : 'IFC4X3.IFCCARTESIANPOINT' IN TYPEOF(SELF\IfcPlacement.Location);
	RefDirIs2D : (NOT (EXISTS (RefDirection))) OR (RefDirection.Dim = 2);
END_ENTITY;