IFC 4.3.0.1 (IFC4X3) development

8.12.3.15 IfcFillAreaStyleHatching

8.12.3.15.1 Semantic 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.

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 .

hatch example 1
Figure 8.12.3.15.A — Example 1

Figure 8.12.3.15.A 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.

hatch example 2
Figure 8.12.3.15.B — Example 2

Figure 8.12.3.15.B 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.

hatch example 3
Figure 8.12.3.15.C — Example 3

Figure 8.12.3.15.C 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.

hatch example 4
Figure 8.12.3.15.D — Example 4

Figure 8.12.3.15.D 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.

hatch example 5
Figure 8.12.3.15.E — 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.

fig 6
Figure 8.12.3.15.F — 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.

8.12.3.15.2 Entity inheritance

8.12.3.15.3 Attributes

# Attribute Type Description
IfcRepresentationItem (2)
LayerAssignment SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems

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.

StyledByItem SET [0:1] OF IfcStyledItem FOR Item

Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.

Click to show 2 hidden inherited attributes Click to hide 2 inherited attributes
IfcFillAreaStyleHatching (5)
1 HatchLineAppearance IfcCurveStyle

The curve style of the hatching lines. Any curve style pattern shall start at the origin of each hatch line.

2 StartOfNextHatchLine IfcHatchLineDistanceSelect

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.

3 PointOfReferenceHatchLine OPTIONAL IfcCartesianPoint

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.

4 PatternStart OPTIONAL IfcCartesianPoint

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.

5 HatchLineAngle IfcPlaneAngleMeasure

A plane angle measure determining the direction of the parallel hatching lines.

Table 8.12.3.15.G

8.12.3.15.4 Formal propositions

Name Description
PatternStart2D

The IfcCartesianPoint, if given as value to PatternStart shall have the dimensionality of 2.

NOT(EXISTS(PatternStart)) OR (PatternStart.Dim = 2)
RefHatchLine2D

The IfcCartesianPoint, if given as value to PointOfReferenceHatchLine shall have the dimensionality of 2.

NOT(EXISTS(PointOfReferenceHatchLine)) OR (PointOfReferenceHatchLine.Dim = 2)
Table 8.12.3.15.H

8.12.3.15.5 Formal representation

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;

8.12.3.15.6 References

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8.12.3.15.7 Changelog

  • where rule, PatternStart2D
  • where rule, RefHatchLine2D
  • where rule, WR21
  • where rule, WR22
  • where rule, WR23