IfcAxis2Placement2D

Item	SPF	XML	Change	Description
IFC4x3_RC1 to IFC4x3_RC2
IfcAxis2Placement2D
Location	X	X	MODIFIED	Type changed from IfcCartesianPoint to IfcPoint.

Semantic definitions at the entity

Entity 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 513 illustrates the definition of the IfcAxis2Placement2D within the two-dimensional coordinate system.
Figure 513 — 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.

Attribute definitions

#	Attribute	Type	Cardinality	Description	G
2	RefDirection	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.].	X
	P :=IfcBuild2Axes(RefDirection)	IfcDirection	L[2:2]	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]	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	G
IfcRepresentationItem
	LayerAssignment	IfcPresentationLayerAssignment @AssignedItems	S[0:1]	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.	X
	StyledByItem	IfcStyledItem @Item	S[0:1]	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.	X
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.	X
	Dim :=Location.Dim	IfcDimensionCount		The space dimensionality of this class, derived from the dimensionality of the location.	X
IfcAxis2Placement2D
2	RefDirection	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.].	X
	P :=IfcBuild2Axes(RefDirection)	IfcDirection	L[2:2]	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]	X

Formal representations

XML Specification

 <xs:element name="IfcAxis2Placement2D" type="ifc:IfcAxis2Placement2D" substitutionGroup="ifc:IfcPlacement" nillable="true"/>

 <xs:complexType name="IfcAxis2Placement2D">

  <xs:complexContent>

   <xs:extension base="ifc:IfcPlacement">

    <xs:sequence>

     <xs:element name="RefDirection" type="ifc:IfcDirection" nillable="true" minOccurs="0"/>

    </xs:sequence>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


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 : 'IFCGEOMETRYRESOURCE.IfcCartesianPoint' IN TYPEOF(SELF\IfcPlacement.Location);
END_ENTITY;

 EXPRESS-G diagram

	Einfügepunkt mit zwei Achsen - zweidimensionaler Raum (2D)
	Axis 2 Placement 2D