IfcLine

Semantic definitions at the entity

Entity definition

Definition from ISO/CD 10303-42:1992: A line is an unbounded curve with constant tangent direction. A line is defined by a point and a direction. The positive direction of the line is in the direction of the Dir vector. The line is parameterized as follows:

P = Pnt
V = Dir
l(u) = P + uV

and the parametric range is -¥ < u < ¥

NOTE Corresponding STEP entity: line. Please refer to ISO/IS 10303-42:1994, p.37 for the final definition of the formal standard. The derived attribute Dim has been added at this level and was therefore demoted from the geometric_representation_item.

HISTORY New class in IFC Release 1.0

Attribute definitions

#	Attribute	Type	Cardinality	Description	A
1	Pnt	IfcCartesianPoint	[1:1]	The location of the line.	X
2	Dir	IfcVector	[1:1]	The direction of the line, the magnitude and units of Dir affect the parameterization of the line.	X

Formal Propositions

Rule	Description
WR1	The dimensionality of the location (IfcCartesianPoint) shall be the same as of the direction (IfcVector).

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	A
IfcRepresentationItem
IfcGeometricRepresentationItem
IfcCurve
	Dim :=IfcCurveDim(SELF)	IfcDimensionCount	[1:1]	The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve.	X
IfcLine
1	Pnt	IfcCartesianPoint	[1:1]	The location of the line.	X
2	Dir	IfcVector	[1:1]	The direction of the line, the magnitude and units of Dir affect the parameterization of the line.	X

Formal representations

XSD Specification

 <xs:element name="IfcLine" type="ifc:IfcLine" substitutionGroup="ifc:IfcCurve" nillable="true"/>

 <xs:complexType name="IfcLine">

  <xs:complexContent>

   <xs:extension base="ifc:IfcCurve">

    <xs:sequence>

     <xs:element name="Pnt" type="ifc:IfcCartesianPoint" nillable="true"/>

     <xs:element name="Dir" type="ifc:IfcVector" nillable="true"/>

    </xs:sequence>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcLine

 SUBTYPE OF (IfcCurve);

  Pnt : IfcCartesianPoint;

  Dir : IfcVector;

 WHERE

  WR1 : Dir.Dim = Pnt.Dim;
END_ENTITY;

 EXPRESS-G diagram