IfcFillAreaStyleHatching

Semantic definitions at the entity

Entity definition

The IfcFillAreaStyleHatching is used to define simple, vector-based hatching patterns, based on styled straight lines. The curve font, color and thickness is given by the HatchLineAppearance, the angle by the HatchLineAngle and the distance to the next hatch line by StartOfNextHatchLine, being either an offset distance or a vector.

NOTE Definition according to ISO 10303-46:
The fill area style hatching defines a styled pattern of curves for hatching an annotation fill area or a surface.

NOTE If the hatch pattern involves two (potentially crossing) rows of hatch lines, then two instances of IfcFillAreaStyleHatching should be assigned to the IfcFillAreaStyle. Both share the same (virtual) point of origin of the hatching that is used by the reference hatch line (or the PointOfReferenceHatchLine if there is an offset).

For better control of the hatching appearance, when using hatch lines with other fonts then continuous, the PatternStart allows to offset the start of the curve font pattern along the reference hatch line (if not given, the PatternStart is at zero distance from the virtual point of origin). If the reference hatch line does not go through the origin (of the virtual hatching coordinate system), it can be offset by using the PatternStart .

NOTE The coordinates of the PatternStart are given relative to the origin of the object coordinate of IfcAnnotationFillArea, or if present, the FillAreaTarget attribute of IfcAnnotationFillArea. The measure values are given in global drawing length units, representing a model hatching, and can be translated into drawing units by the TargetScale for a scale depended IfcGeometricRepresentationSubcontext, if provided.

DEPRECATION The use of PointOfReferenceHatchLine is deprecated.

Figure 360 illustrates hatch attributes.

	Example 1 This example shows simple hatching given by using a curve font "continuous" at HatchLineAppearance. The distance of hatch lines is given by a positive length measure. The angle (here 45' if measures in degree) is provided by HatchLineAngle. The PatternStart is set to NIL ($) in this example.		Example 2 This shows hatching from example 1 with using a different curve font at HatchLineAppearance. The distance of hatch lines is given by a positive length measure, therefore the font pattern start is at a point at the next hatch line given by a vector being perpendicular to the point of origin at the reference hatch line. The PatternStart is set to NIL ($) in this example.
	Example 3 This example uses hatching from example 2 with a vector to determine the pattern start of the next hatch lines. The pattern start is the beginning of the first visual curve font pattern segment at IfcCurveFont.CurveFont. The PatternStart is set to NIL ($) in this example.		Example 4 This example uses hatching from example 3 where the pattern start is offset from the point of origin at the reference hatch line. That is, the first visible curve font pattern segment now does not start at the point of origin at the reference hatch line.
	Example 5 This example uses hatching from example 4 where the hatch pattern is shifted against the underlying coordinate system. The point that is mapped to the insertion point of the IfcAnnotationFillAreaOccurrence now has an X and Y offset from the start of the reference hatch line. That is, the reference hatch line now does not go through the insertion point of the hatching.		Example 6 This example shows use of IfcFillAreaStyleHatching attributes for two IfcFillAreaStyleHatching's within one IfcFillAreaStyle. Note that the PatternStart now displaces both the reference hatch line from the point of origin and the start of the curve pattern. This can be used in cases when more than one IfcFillAreaStyleHatching is used in an IfcFillAreaStyle in order to place rows of hatch lines with an offset from each other.

Figure 360 — Fill area style hatching

NOTE Entity adapted from fill_area_style_hatching defined in ISO10303-46

HISTORY New entity in IFC2x2.

IFC2x3 CHANGE The IfcFillAreaStyleHatching has been changed by making the attributes PatternStart and PointOfReferenceHatchLine OPTIONAL. The attribute StartOfNextHatchLine has changed to a SELECT with the additional choice of IfcPositiveLengthMeasure. Upward compatibility for file based exchange is guaranteed.

IFC4 CHANGE The attribute data type for StartOfNextHatchLine has been changed to be a select of IfcPositiveLengthMeasure and IfcVector.

Attribute definitions

#	Attribute	Type	Cardinality	Description	C
1	HatchLineAppearance	IfcCurveStyle	[1:1]	The curve style of the hatching lines. Any curve style pattern shall start at the origin of each hatch line.	X
2	StartOfNextHatchLine	IfcHatchLineDistanceSelect	[1:1]	A repetition factor that determines the distance between adjacent hatch lines. The factor can either be defined by a parallel offset, or by a repeat factor provided by IfcVector.	X
3	PointOfReferenceHatchLine	IfcCartesianPoint	[0:1]	A Cartesian point which defines the offset of the reference hatch line from the origin of the (virtual) hatching coordinate system. The origin is used for mapping the fill area style hatching onto an annotation fill area or surface. The reference hatch line would then appear with this offset from the fill style target point. If not given the reference hatch lines goes through the origin of the (virtual) hatching coordinate system.	X
4	PatternStart	IfcCartesianPoint	[0:1]	A distance along the reference hatch line which is the start point for the curve style font pattern of the reference hatch line. If not given, the start point of the curve style font pattern is at the (virtual) hatching coordinate system.	X
5	HatchLineAngle	IfcPlaneAngleMeasure	[1:1]	A plane angle measure determining the direction of the parallel hatching lines.	X

Formal Propositions

Rule	Description
PatternStart2D	The IfcCartesianPoint, if given as value to PatternStart shall have the dimensionality of 2.
RefHatchLine2D	The IfcCartesianPoint, if given as value to PointOfReferenceHatchLine shall have the dimensionality of 2.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
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.	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.	X
IfcGeometricRepresentationItem
IfcFillAreaStyleHatching
1	HatchLineAppearance	IfcCurveStyle	[1:1]	The curve style of the hatching lines. Any curve style pattern shall start at the origin of each hatch line.	X
2	StartOfNextHatchLine	IfcHatchLineDistanceSelect	[1:1]	A repetition factor that determines the distance between adjacent hatch lines. The factor can either be defined by a parallel offset, or by a repeat factor provided by IfcVector.	X
3	PointOfReferenceHatchLine	IfcCartesianPoint	[0:1]	A Cartesian point which defines the offset of the reference hatch line from the origin of the (virtual) hatching coordinate system. The origin is used for mapping the fill area style hatching onto an annotation fill area or surface. The reference hatch line would then appear with this offset from the fill style target point. If not given the reference hatch lines goes through the origin of the (virtual) hatching coordinate system.	X
4	PatternStart	IfcCartesianPoint	[0:1]	A distance along the reference hatch line which is the start point for the curve style font pattern of the reference hatch line. If not given, the start point of the curve style font pattern is at the (virtual) hatching coordinate system.	X
5	HatchLineAngle	IfcPlaneAngleMeasure	[1:1]	A plane angle measure determining the direction of the parallel hatching lines.	X

Formal representations

XSD Specification

 <xs:element name="IfcFillAreaStyleHatching" type="ifc:IfcFillAreaStyleHatching" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>

 <xs:complexType name="IfcFillAreaStyleHatching">

  <xs:complexContent>

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

    <xs:sequence>

     <xs:element name="HatchLineAppearance" type="ifc:IfcCurveStyle" nillable="true"/>

     <xs:element name="StartOfNextHatchLine">

      <xs:complexType>

       <xs:group ref="ifc:IfcHatchLineDistanceSelect"/>

      </xs:complexType>

     </xs:element>

     <xs:element name="PointOfReferenceHatchLine" type="ifc:IfcCartesianPoint" nillable="true" minOccurs="0"/>

     <xs:element name="PatternStart" type="ifc:IfcCartesianPoint" nillable="true" minOccurs="0"/>

    </xs:sequence>

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

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcFillAreaStyleHatching

 SUBTYPE OF (IfcGeometricRepresentationItem);

  HatchLineAppearance : IfcCurveStyle;

  StartOfNextHatchLine : IfcHatchLineDistanceSelect;

  PointOfReferenceHatchLine : OPTIONAL IfcCartesianPoint;

  PatternStart : OPTIONAL IfcCartesianPoint;

  HatchLineAngle : IfcPlaneAngleMeasure;

 WHERE

  PatternStart2D : NOT(EXISTS(PatternStart)) OR (PatternStart.Dim = 2)
;
  RefHatchLine2D : NOT(EXISTS(PointOfReferenceHatchLine)) OR (PointOfReferenceHatchLine.Dim = 2);
END_ENTITY;

 EXPRESS-G diagram

	Füllfläche - Schraffurstil
	Fill Area Style Hatching