Curve Segment 2D |

Item | SPF | XML | Change | Description |
---|---|---|---|---|

IFC4x1 Release Candidate 1 |
||||

IfcCurveSegment2D | ADDED |

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 | Type | Cardinality | Description | G |
---|---|---|---|---|---|

1 | StartPoint | IfcCartesianPoint | The start point of the 2D curve as x/y coordinates defined by a 2D Cartesian point. | X | |

2 | StartDirection | IfcPlaneAngleMeasure | 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 | The length along the curve | X |

# | Attribute | Type | Cardinality | Description | G |
---|---|---|---|---|---|

IfcRepresentationItem | |||||

LayerAssignment | IfcPresentationLayerAssignment @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 IFC4 CHANGE The inverse attribute | X | |

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.
IFC2x3 CHANGE The inverse attribute | X | |

IfcGeometricRepresentationItem | |||||

IfcCurve | |||||

Dim :=IfcCurveDim(SELF) | IfcDimensionCount | The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve. | X | ||

IfcBoundedCurve | |||||

PositioningElement | IfcLinearPositioningElement @Axis | ? | X | ||

IfcCurveSegment2D | |||||

1 | StartPoint | IfcCartesianPoint | The start point of the 2D curve as x/y coordinates defined by a 2D Cartesian point. | X | |

2 | StartDirection | IfcPlaneAngleMeasure | 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 | The length along the curve | X |

` <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>

```
ENTITY IfcCurveSegment2D
```

ABSTRACT SUPERTYPE OF(ONEOF(IfcCircularArcSegment2D, IfcLineSegment2D, IfcTransitionCurveSegment2D))

SUBTYPE OF (IfcBoundedCurve)**;**

StartPoint : IfcCartesianPoint;

StartDirection : IfcPlaneAngleMeasure;

SegmentLength : IfcPositiveLengthMeasure;

END_ENTITY;

References: IfcAlignment2DHorizontalSegment