IfcAxis2Placement2D

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 337 illustrates the definition of the IfcAxis2Placement2D within the two-dimensional coordinate system.
Figure 337 — 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	C
2	RefDirection	IfcDirection	[0:1]	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	C
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.	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.	X
IfcGeometricRepresentationItem
IfcPlacement
1	Location	IfcCartesianPoint	[1:1]	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	[1:1]	The space dimensionality of this class, derived from the dimensionality of the location.	X
IfcAxis2Placement2D
2	RefDirection	IfcDirection	[0:1]	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

XSD 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;
END_ENTITY;

 EXPRESS-G diagram

	Einfügepunkt mit zwei Achsen - zweidimensionaler Raum (2D)
	Axis2 Placement2 D