IfcGeometricRepresentationSubContext

Semantic definitions at the entity

Entity definition

Definition from IAI: The IfcGeometricRepresentationSubContext defines the context that applies to several shape representations of a product being a sub context, sharing the WorldCoordinateSystem, CoordinateSpaceDimension, Precision and TrueNorth attributes with the parent IfcGeometricRepresentationContext.

The IfcGeometricRepresentationSubContext is used to define semantically distinguished representation types for different information content, dependent on the representation view and the target scale. It can be used to control the level of detail of the shape representation that is most applicable to this geometric representation context. addition the sub context is used to control the later appearance of the IfcShapeRepresentation within a plot view.

NOTE If the IfcShapeRepresentation using this sub context has IfcStyledItem's assigned to the Items, the presentation style information (e.g. IfcCurveStyle, IfcTextStyle) associated with the IfcStyledItem is given in target plot dimensions. E.g. a line thickness (IfcCurveStyle.CurveWidth) is given by a thickness measure relating to the thickness for a plot within the (range of) target scale.

Each IfcProduct can then have several instances of subtypes of IfcRepresentation, each being assigned to a different geometric representation context (IfcGeometricRepresentationContext or IfcGeometricRepresentationSubContext). The application can then choose the most appropriate representation for showing the geometric shape of the product, depending on the target view and scale.

NOTE The provision of a model view (IfcGeometricRepresentationContext.ContextType = 'Model') is mandatory. Instances of IfcGeometricRepresentationSubContext relate to it as its ParentContext.

EXAMPLE Instances of IfcGeometricRepresentationSubContext can be used to handle the multi-view blocks or macros, which are used in CAD programs to store several scale and/or view dependent geometric representations of the same object.

HISTORY New entity in Release IFC 2x Edition 2.

Attribute definitions

#	Attribute	Type	Cardinality	Description	A
7	ParentContext	IfcGeometricRepresentationContext	[1:1]	Parent context from which the sub context derives its world coordinate system, precision, space coordinate dimension and true north.	X
8	TargetScale	IfcPositiveRatioMeasure	[0:1]	The target plot scale of the representation to which this representation context applies. Scale indicates the target plot scale for the representation sub context, all annotation styles are given in plot dimensions according to this target plot scale. If multiple instances of IfcGeometricRepresentationSubContext are given having the same TargetView value, the target plot scale applies up to the next smaller scale, or up to unlimited small scale. Note: Scale 1:100 (given as 0.01 within TargetScale) is bigger then 1:200 (given as 0.005 within TargetScale).	X
9	TargetView	IfcGeometricProjectionEnum	[1:1]	Target view of the representation to which this representation context applies.	X
10	UserDefinedTargetView	IfcLabel	[0:1]	User defined target view, this attribute value shall be given, if the TargetView attribute is set to USERDEFINED.	X
	WorldCoordinateSystem :=ParentContext.WorldCoordinateSystem	IfcAxis2Placement	[1:1]		X
	CoordinateSpaceDimension :=ParentContext.CoordinateSpaceDimension	IfcDimensionCount	[1:1]
	TrueNorth :=NVL(ParentContext.TrueNorth,SELF.WorldCoordinateSystem.P[2])	IfcDirection	[1:1]
	Precision :=NVL(ParentContext.Precision,1.E-5)	REAL	[1:1]

Formal Propositions

Rule	Description
WR31	The parent context shall not be another geometric representation sub context.
WR32	The attribute UserDefinedTargetView shall be given, if the attribute TargetView is set to USERDEFINED.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	A
IfcRepresentationContext
1	ContextIdentifier	IfcLabel	[0:1]	The optional identifier of the representation context as used within a project.	X
2	ContextType	IfcLabel	[0:1]	The description of the type of a representation context. The supported values for context type are to be specified by implementers agreements.	X
	RepresentationsInContext	IfcRepresentation @ContextOfItems	S[0:?]	All shape representations that are defined in the same representation context.
IfcGeometricRepresentationContext
	HasSubContexts	IfcGeometricRepresentationSubContext @ParentContext	S[0:?]	The set of IfcGeometricRepresentationSubContexts that refer to this IfcGeometricRepresentationContext.	X
IfcGeometricRepresentationSubContext
7	ParentContext	IfcGeometricRepresentationContext	[1:1]	Parent context from which the sub context derives its world coordinate system, precision, space coordinate dimension and true north.	X
8	TargetScale	IfcPositiveRatioMeasure	[0:1]	The target plot scale of the representation to which this representation context applies. Scale indicates the target plot scale for the representation sub context, all annotation styles are given in plot dimensions according to this target plot scale. If multiple instances of IfcGeometricRepresentationSubContext are given having the same TargetView value, the target plot scale applies up to the next smaller scale, or up to unlimited small scale. Note: Scale 1:100 (given as 0.01 within TargetScale) is bigger then 1:200 (given as 0.005 within TargetScale).	X
9	TargetView	IfcGeometricProjectionEnum	[1:1]	Target view of the representation to which this representation context applies.	X
10	UserDefinedTargetView	IfcLabel	[0:1]	User defined target view, this attribute value shall be given, if the TargetView attribute is set to USERDEFINED.	X
	WorldCoordinateSystem :=ParentContext.WorldCoordinateSystem	IfcAxis2Placement	[1:1]		X
	CoordinateSpaceDimension :=ParentContext.CoordinateSpaceDimension	IfcDimensionCount	[1:1]
	TrueNorth :=NVL(ParentContext.TrueNorth,SELF.WorldCoordinateSystem.P[2])	IfcDirection	[1:1]
	Precision :=NVL(ParentContext.Precision,1.E-5)	REAL	[1:1]

Formal representations

XSD Specification

 <xs:complexType name="IfcGeometricRepresentationSubContext-temp" abstract="true">

  <xs:complexContent>

   <xs:restriction base="ifc:IfcGeometricRepresentationContext">

    <xs:sequence/>

   </xs:restriction>

  </xs:complexContent>

 </xs:complexType>

 <xs:element name="IfcGeometricRepresentationSubContext" type="ifc:IfcGeometricRepresentationSubContext" substitutionGroup="ifc:IfcGeometricRepresentationContext" nillable="true"/>

 <xs:complexType name="IfcGeometricRepresentationSubContext">

  <xs:complexContent>

   <xs:extension base="ifc:IfcGeometricRepresentationSubContext-temp">

    <xs:sequence>

     <xs:element name="ParentContext" type="ifc:IfcGeometricRepresentationContext" nillable="true"/>

    </xs:sequence>

    <xs:attribute name="TargetScale" type="ifc:IfcPositiveRatioMeasure" use="optional"/>

    <xs:attribute name="TargetView" type="ifc:IfcGeometricProjectionEnum" use="optional"/>

    <xs:attribute name="UserDefinedTargetView" type="ifc:IfcLabel" use="optional"/>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcGeometricRepresentationSubContext

 SUBTYPE OF (IfcGeometricRepresentationContext);

  ParentContext : IfcGeometricRepresentationContext;

  TargetScale : OPTIONAL IfcPositiveRatioMeasure;

  TargetView : IfcGeometricProjectionEnum;

  UserDefinedTargetView : OPTIONAL IfcLabel;

 DERIVE

  SELF\IfcGeometricRepresentationContext.WorldCoordinateSystem : IfcAxis2Placement := ParentContext.WorldCoordinateSystem;

  SELF\IfcGeometricRepresentationContext.CoordinateSpaceDimension : IfcDimensionCount := ParentContext.CoordinateSpaceDimension;

  SELF\IfcGeometricRepresentationContext.TrueNorth : IfcDirection := NVL(ParentContext.TrueNorth,SELF.WorldCoordinateSystem.P[2]);

  SELF\IfcGeometricRepresentationContext.Precision : REAL := NVL(ParentContext.Precision,1.E-5);

 WHERE

  WR31 : NOT('IFCREPRESENTATIONRESOURCE.IFCGEOMETRICREPRESENTATIONSUBCONTEXT' IN TYPEOF(ParentContext));
  WR32 :  (TargetView <> IfcGeometricProjectionEnum.USERDEFINED) OR 
((TargetView =  IfcGeometricProjectionEnum.USERDEFINED) AND 
 EXISTS(UserDefinedTargetView)) ;
END_ENTITY;

 EXPRESS-G diagram