IfcVector

BACnet MVD

#### IfcVector

Natural language names

| Vektor
| Vector
| Vecteur

##### Semantic definitions at the entity

Entity definition

An IfcVector is a geometric representation item having both a magnitude and direction. The magnitude of the vector is solely defined by the Magnitude attribute and the direction is solely defined by the Orientation attribute.

> NOTE The DirectionRatios of the Orientation attribute are not used to define the magnitude.

> NOTE Definition according to ISO/CD 10303-42:1992
> The vector is defined in terms of the direction and magnitude of the vector. The value of the magnitude attribute defines the magnitude of the vector. The magnitude of the vector can not be reliable calculated from the components of the orientation attribute. This form of representation was selected to reduce problems with numerical instability. For example a vector of magnitude 2.0 mm and equally inclined to the coordinate axes could be represented with Orientation attribute of (1.0,1.0,1.0).

> NOTE Entity adapted from vector defined in ISO 10303-42.

> HISTORY New entity in IFC1.0

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
1 | Orientation | IfcDirection |  | The direction of the vector. | X | X
2 | Magnitude | IfcLengthMeasure |  | The magnitude of the vector. All vectors of Magnitude 0.0 are regarded as equal in value regardless of the orientation attribute. | X | X
| Dim :=Orientation.Dim | IfcDimensionCount |  | The space dimensionality of this class, it is derived from Orientation | X | X

Formal Propositions

Rule | Description
--- | ---
MagGreaterOrEqualZero | The magnitude shall be positive or zero.

##### 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
IfcVector
1 | Orientation | IfcDirection |  | The direction of the vector. | X | X
2 | Magnitude | IfcLengthMeasure |  | The magnitude of the vector. All vectors of Magnitude 0.0 are regarded as equal in value regardless of the orientation attribute. | X | X
| Dim :=Orientation.Dim | IfcDimensionCount |  | The space dimensionality of this class, it is derived from Orientation | X | X

##### Formal representations

XML Specification
`<xs:element name="IfcVector" type="ifc:IfcVector" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>
<xs:complexType name="IfcVector">
<xs:complexContent>
<xs:extension base="ifc:IfcGeometricRepresentationItem">
<xs:sequence>
<xs:element name="Orientation" type="ifc:IfcDirection" nillable="true"/>
</xs:sequence>
<xs:attribute name="Magnitude" type="ifc:IfcLengthMeasure" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcVector
SUBTYPE OF (IfcGeometricRepresentationItem);
Orientation : IfcDirection;
Magnitude : IfcLengthMeasure;
DERIVE
Dim : IfcDimensionCount := Orientation.Dim;
WHERE
MagGreaterOrEqualZero : Magnitude >= 0.0;
END_ENTITY;

EXPRESS-G diagram

`

References: IfcLine IfcSurfaceOfLinearExtrusion IfcVectorOrDirection IfcFillAreaStyleTiles IfcHatchLineDistanceSelect

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