IfcAlignment2DCantSegment

Item	SPF	XML	Change	Description
IFC4x2 to IFC4x3_RC1
IfcAlignment2DCantSegment			ADDED

Semantic definitions at the entity

Entity definition

An IfcAlignment2DCantSegment is an individual segment along the IfcAlignment2DCant. The cant alignment is defined by ordered segments that connect end-to-start. The points defined in a cant alignment segment are defined in a plane with x = distance along horizontal alignment and y = height relative to projected points in vertical alignment. The following cant segment types are defined:

line segment - IfcAlignment2DCantSegLine
transition curve segment - IfcAlignment2DCantSegTransition

For each cant segment, the following information is provided:

the start point, defined by distance along the horizontal alignment
the length (as horizontal length along the distance along (not the curve segment length))
the start cant, given by the values of left cant and right cant, measured relatively to vertical alignment
the end cant, given by the values of left cant and right cant, measured from vertical alignment
the information of tangential continuity that can be used to check continuity of segments (e.g. invalid sudden change of cant or missing cant information if end point and starting point differ over a threshold).

Attribute definitions

#	Attribute	Type	Cardinality	Description	G
4	StartDistAlong	IfcPositiveLengthMeasure		Distance along the horizontal alignment, measured along the IfcAlignment2DHorizontal given in the length unit of the global IfcUnitAssignment.	X
5	HorizontalLength	IfcPositiveLengthMeasure		Length measured as distance along the horizontal alignment of the segment.	X
6	StartCantLeft	IfcLengthMeasure		Length measured for the left cant at the beginning of the segment.	X
7	EndCantLeft	IfcLengthMeasure	?	Length measured for the left cant at the end of the segment.	X
8	StartCantRight	IfcLengthMeasure		Length measured for the right cant at the beginning of the segment.	X
9	EndCantRight	IfcLengthMeasure	?	Length measured for the right cant at the end of the segment.	X
	ToCant	IfcAlignment2DCant @Segments	S[1:1]		X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	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 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
	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 StyledByItem has been added.	X
IfcGeometricRepresentationItem
IfcAlignment2DSegment
1	TangentialContinuity	IfcBoolean	?	Connectivity between the continuous segments is not enforced per se to be tangential. Setting "TangentialContinuity" to True means that the current segment shall continue with tangential continuity to the previous one.	X
2	StartTag	IfcLabel	?	Tag to annotate the start point of the alignment segment.	X
3	EndTag	IfcLabel	?	Tag to annotate the end point of the alignment segment.	X
IfcAlignment2DCantSegment
4	StartDistAlong	IfcPositiveLengthMeasure		Distance along the horizontal alignment, measured along the IfcAlignment2DHorizontal given in the length unit of the global IfcUnitAssignment.	X
5	HorizontalLength	IfcPositiveLengthMeasure		Length measured as distance along the horizontal alignment of the segment.	X
6	StartCantLeft	IfcLengthMeasure		Length measured for the left cant at the beginning of the segment.	X
7	EndCantLeft	IfcLengthMeasure	?	Length measured for the left cant at the end of the segment.	X
8	StartCantRight	IfcLengthMeasure		Length measured for the right cant at the beginning of the segment.	X
9	EndCantRight	IfcLengthMeasure	?	Length measured for the right cant at the end of the segment.	X
	ToCant	IfcAlignment2DCant @Segments	S[1:1]		X

Formal representations

XML Specification

 <xs:element name="IfcAlignment2DCantSegment" type="ifc:IfcAlignment2DCantSegment" abstract="true" substitutionGroup="ifc:IfcAlignment2DSegment" nillable="true"/>

 <xs:complexType name="IfcAlignment2DCantSegment" abstract="true">

  <xs:complexContent>

   <xs:extension base="ifc:IfcAlignment2DSegment">

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

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

    <xs:attribute name="StartCantLeft" type="ifc:IfcLengthMeasure" use="optional"/>

    <xs:attribute name="EndCantLeft" type="ifc:IfcLengthMeasure" use="optional"/>

    <xs:attribute name="StartCantRight" type="ifc:IfcLengthMeasure" use="optional"/>

    <xs:attribute name="EndCantRight" type="ifc:IfcLengthMeasure" use="optional"/>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcAlignment2DCantSegment

 ABSTRACT SUPERTYPE OF(ONEOF(IfcAlignment2DCantSegLine, IfcAlignment2DCantSegTransition))

 SUBTYPE OF (IfcAlignment2DSegment);

  StartDistAlong : IfcPositiveLengthMeasure;

  HorizontalLength : IfcPositiveLengthMeasure;

  StartCantLeft : IfcLengthMeasure;

  EndCantLeft : OPTIONAL IfcLengthMeasure;

  StartCantRight : IfcLengthMeasure;

  EndCantRight : OPTIONAL IfcLengthMeasure;

 INVERSE

  ToCant : SET [1:1] OF IfcAlignment2DCant FOR Segments;

END_ENTITY;

 EXPRESS-G diagram