IfcCurveSegment2D

Natural language names
Curve Segment 2D
Change log
ItemSPFXMLChangeDescription
IFC4x1 Release Candidate 1
    IfcCurveSegment2DADDED
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.

NOTE  Such 2D curves are used in particular by horizontal alignment segments.
Attribute definitions
#AttributeTypeCardinalityDescription G
1StartPointIfcCartesianPoint The start point of the 2D curve as x/y coordinates defined by a 2D Cartesian point.X
2StartDirectionIfcPlaneAngleMeasure 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
3SegmentLengthIfcPositiveLengthMeasure The length along the curveX
Inherited definitions from supertypes
Entity inheritance IfcCircularArcSegment2D IfcLineSegment2D IfcTransitionCurveSegment2D IfcBoundedCurve IfcCurve IfcGeometricRepresentationItem IfcRepresentationItem
Attribute inheritance
#AttributeTypeCardinalityDescriptionG
IfcRepresentationItem
LayerAssignmentIfcPresentationLayerAssignment
@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.
IFC2x3 CHANGE  The inverse attribute LayerAssignments has been added.
IFC4 CHANGE  The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed.
X
StyledByItemIfcStyledItem
@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.
IFC2x3 CHANGE  The inverse attribute StyledByItem has been added.
X
IfcGeometricRepresentationItem
IfcCurve
Dim
:=IfcCurveDim(SELF)
IfcDimensionCountThe space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve. X
IfcBoundedCurve
PositioningElementIfcLinearPositioningElement
@Axis
? X
IfcCurveSegment2D
1StartPointIfcCartesianPoint The start point of the 2D curve as x/y coordinates defined by a 2D Cartesian point.X
2StartDirectionIfcPlaneAngleMeasure 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
3SegmentLengthIfcPositiveLengthMeasure The length along the curveX
Formal representations
XML 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, IfcLineSegment2D, IfcTransitionCurveSegment2D))
 SUBTYPE OF (IfcBoundedCurve);
  StartPoint : IfcCartesianPoint;
  StartDirection : IfcPlaneAngleMeasure;
  SegmentLength : IfcPositiveLengthMeasure;
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

References  References: IfcAlignment2DHorizontalSegment

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