IfcVector

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

Formal representations

XSD 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

	Vektor
	Vector
	Vecteur