IfcAxis2Placement2D

BACnet MVD

#### IfcAxis2Placement2D

Natural language names

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

##### 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 312 illustrates the definition of the IfcAxis2Placement2D within the two-dimensional coordinate system.

Figure 312 — 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 | B
--- | --- | --- | --- | --- | ---
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.].

XX
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] XX

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
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

X

IfcGeometricRepresentationItem
IfcPlacement
1 | Location | IfcCartesianPoint |  | The geometric position of a reference point, such as the center of a circle, of the item to be located. | X | X
| Dim :=Location.Dim | IfcDimensionCount |  | The space dimensionality of this class, derived from the dimensionality of the location. | X | 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 | 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 | 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;
END_ENTITY;

EXPRESS-G diagram

`

References: IfcAxis2Placement IfcParameterizedProfileDef

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