8.9.3.30 IfcDirection

The IfcDirection provides a direction in two or three dimensional space depending on the number of DirectionRatio's provided. The IfcDirection does not imply a vector length, and the direction ratios does not have to be normalized.

Definition according to ISO/CD 10303-42:1992 This entity defines a general direction vector in two or three dimensional space. The actual magnitudes of the components have no effect upon the direction being defined, only the ratios X:Y:Z or X:Y are significant. The components of this entity are not normalized. If a unit vector is required it should be normalized before use. Entity adapted from direction defined in ISO 10303-42. New entity in IFC1.0

8.9.3.30.2 Entity inheritance

8.9.3.30.3 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. 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.
	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. IFC2x3-CHANGE The inverse attribute StyledByItem has been added.
Click to show 2 hidden inherited attributes Click to hide 2 inherited attributes
IfcDirection (2)
1	DirectionRatios	LIST [2:3] OF IfcReal	The components in the direction of X axis (DirectionRatios[1]), of Y axis (DirectionRatios[2]), and of Z axis (DirectionRatios[3])
*	Dim	IfcDimensionCount	This attribute is formally derived. `HIINDEX(DirectionRatios)` The space dimensionality of this class, defined by the number of real in the list of DirectionRatios.

Table 8.9.3.30.A

8.9.3.30.4 Formal propositions

Name	Description
MagnitudeGreaterZero	The magnitude of the direction vector shall be greater than zero.
`SIZEOF(QUERY(Tmp <* DirectionRatios \| Tmp <> 0.0)) > 0`

Table 8.9.3.30.B

8.9.3.30.5 Formal representation

ENTITY IfcDirection
 SUBTYPE OF (IfcGeometricRepresentationItem);
	DirectionRatios : LIST [2:3] OF IfcReal;
 DERIVE
	 Dim : IfcDimensionCount := HIINDEX(DirectionRatios);
 WHERE
	MagnitudeGreaterZero : SIZEOF(QUERY(Tmp <* DirectionRatios | Tmp <> 0.0)) > 0;
END_ENTITY;

8.9.3.30 IfcDirection

8.9.3.30.1 Semantic definition

8.9.3.30.2 Entity inheritance

8.9.3.30.3 Attributes

8.9.3.30.4 Formal propositions

8.9.3.30.5 Formal representation

8.9.3.30.6 References

8.9.3.30.7 Changelog

8.9.3.30.7.1 IFC4