IfcCurveSegment2D

Item	SPF	XML	Change	Description
IFC4 ADD1 to IFC4x1
IfcCurveSegment2D			ADDED

Semantic definitions at the entity

Entity definition

The abstract definition of a bounded 2D curve representation item. Each curve segment is defined by a start point, a start direction, a segment length and additional curve geometry parameter. It defines arcs without the need to use a trimmed curve.

Such 2D curves are used in particular by horizontal alignment segments.

Attribute definitions

#	Attribute	Type	Cardinality	Description	B
1	StartPoint	IfcCartesianPoint	[1:1]	The start point of the 2D curve as x/y coordinates defined by a 2D Cartesian point.	X
2	StartDirection	IfcPlaneAngleMeasure	[1:1]	The direction of the tangent at the start point. Direction value 0. indicates a curve with a start tangent along the positive x-axis. Values increases counter-clockwise, and decreases clockwise. Depending on the plane angle unit, either degree or radians, the sensible range is -360° ≤ n ≤ 360° (or -2π ≤ n ≤ 2π). Values larger then a full circle (>\|360°\| or >\|2 π\| shall not be used.	X
3	SegmentLength	IfcPositiveLengthMeasure	[1:1]	The length along the curve	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	B
IfcRepresentationItem
	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
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
IfcBoundedCurve
IfcCurveSegment2D
1	StartPoint	IfcCartesianPoint	[1:1]	The start point of the 2D curve as x/y coordinates defined by a 2D Cartesian point.	X
2	StartDirection	IfcPlaneAngleMeasure	[1:1]	The direction of the tangent at the start point. Direction value 0. indicates a curve with a start tangent along the positive x-axis. Values increases counter-clockwise, and decreases clockwise. Depending on the plane angle unit, either degree or radians, the sensible range is -360° ≤ n ≤ 360° (or -2π ≤ n ≤ 2π). Values larger then a full circle (>\|360°\| or >\|2 π\| shall not be used.	X
3	SegmentLength	IfcPositiveLengthMeasure	[1:1]	The length along the curve	X

Formal representations

XSD Specification

 <xs:element name="IfcCurveSegment2D" type="ifc:IfcCurveSegment2D" abstract="true" substitutionGroup="ifc:IfcBoundedCurve" nillable="true"/>

 <xs:complexType name="IfcCurveSegment2D" abstract="true">

  <xs:complexContent>

   <xs:extension base="ifc:IfcBoundedCurve">

    <xs:sequence>

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

    </xs:sequence>

    <xs:attribute name="StartDirection" type="ifc:IfcPlaneAngleMeasure" use="optional"/>

    <xs:attribute name="SegmentLength" type="ifc:IfcPositiveLengthMeasure" use="optional"/>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcCurveSegment2D

 ABSTRACT SUPERTYPE OF(ONEOF(IfcCircularArcSegment2D, IfcClothoidalArcSegment2D, IfcLineSegment2D))

 SUBTYPE OF (IfcBoundedCurve);

  StartPoint : IfcCartesianPoint;

  StartDirection : IfcPlaneAngleMeasure;

  SegmentLength : IfcPositiveLengthMeasure;

END_ENTITY;

 EXPRESS-G diagram