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 (x-axis) as [1.,0.] and P (y-axis) as [0.,1.].
Figure 1 illustrates the definition of the IfcAxis2Placement2D within the two-dimensional coordinate system.
Figure 1 — Axis2 placement 2D
NOTE Definition according to ISO/CD 10303-42:1992
The location and orientation in two dimensional space of two mutually perpendicular axes. An axis2_placement_2d is defined in terms of a point, (inherited from the placement supertype), and an axis. It can be used to locate and originate an object in two dimensional space and to define a placement coordinate system. The entity includes a point which forms the origin of the placement coordinate system. A direction vector is required to complete the definition of the placement coordinate system. The reference direction defines the placement X axis direction, the placement Y axis is derived from this.
NOTE Entity adapted from axis2_placement_2d defined in ISO 10303-42.
HISTORY New entity in IFC1.5.
|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.
|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.|
|2||RefDirection||OPTIONAL IfcDirection||The direction used to determine the direction of the local X axis. If a value is omited that it defaults to [1.0, 0.0.].|
|P||INVALID||_P_: The normalized direction of the placement X Axis. This is [1.0,0.0] if RefDirection is omitted. |
_P_: The normalized direction of the placement Y Axis. This is a derived attribute and is orthogonal to P. If RefDirection is omitted, it defaults to [0.0,1.0]
ENTITY IfcAxis2Placement2D SUBTYPE OF (IfcPlacement); RefDirection : OPTIONAL IfcDirection; DERIVE P : LIST [2:2] OF IfcDirection := IfcBuild2Axes(RefDirection); WHERE RefDirIs2D : (NOT (EXISTS (RefDirection))) OR (RefDirection.Dim = 2); LocationIs2D : SELF\IfcPlacement.Location.Dim = 2; LocationIsCP : 'IFC4X3_DEV_a1492713.IFCCARTESIANPOINT' IN TYPEOF(SELF\IfcPlacement.Location); END_ENTITY;