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IfcLine

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

EXPRESS specification:

ENTITY IfcLine
SUBTYPE OF ( IfcCurve);
Pnt  :  IfcCartesianPoint;
Dir  :  IfcVector;
WHERE
WR1  :  Dir.Dim = Pnt.Dim;
END_ENTITY;

Attribute definitions:

Pnt  :  The location of the line.
Dir  :  The direction of the line, the magnitude and units of Dir affect the parameterization of the line.

Formal Propositions:

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

References (2):

Name Type Referred through Express-G
IfcCurve Entity
Subtype
Diagram 5
IfcSurfaceOfRevolution Entity
Attribute 'AxisLine'
Diagram 8

Inheritance graph

ENTITY IfcLine;
ENTITY IfcCurve;
DERIVE
Dim  :  IfcDimensionCount :=  IfcCurveDim(SELF);
ENTITY IfcLine;
Pnt  :  IfcCartesianPoint;
Dir  :  IfcVector;
END_ENTITY;