IfcVector

Semantic definitions at the entity

Entity definition

Definition from 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.

NOTE: 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: Corresponding STEP entity: vector. Please refer to ISO/IS 10303-42:1994, p.27 for the final definition of the formal standard. The derived attribute Dim has been added (see also note at IfcGeometricRepresentationItem).

HISTORY: New entity in IFC Release 1.0

Attribute definitions

#	Attribute	Type	Cardinality	Description	A
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
WR1	The magnitude shall be positive or zero.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	A
IfcRepresentationItem
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

  WR1 : Magnitude >= 0.0;
END_ENTITY;

 EXPRESS-G diagram