IFC 4.3.x development

8.9.3.76 IfcVector

Change log

IFC4

additionswhere_rulesMagGreaterOrEqualZero
deletionswhere_rulesWR1

8.9.3.76.1 Semantic definitions at the entity

An IfcVector is a geometric representation item having both a magnitude and direction. The magnitude of the vector is solely defined by the Magnitude attribute and the direction is solely defined by the Orientation attribute.

NOTE  The DirectionRatios of the Orientation attribute are not used to define the magnitude.

NOTE  Definition according to ISO/CD 10303-42:1992
The vector is defined in terms of the direction and magnitude of the vector. The value of the magnitude attribute defines the magnitude of the vector. The magnitude of the vector can not be reliable calculated from the components of the orientation attribute. This form of representation was selected to reduce problems with numerical instability. For example a vector of magnitude 2.0 mm and equally inclined to the coordinate axes could be represented with Orientation attribute of (1.0,1.0,1.0).

NOTE  Entity adapted from vector defined in ISO 10303-42.

HISTORY  New entity in IFC1.0

8.9.3.76.1 Attributes

# Attribute Type Description
IfcRepresentationItem
LayerAssignmentSET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItemsAssignment 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.
IfcGeometricRepresentationItem
IfcVector
1 Orientation IfcDirection The direction of the vector.
2 Magnitude IfcLengthMeasure The magnitude of the vector. All vectors of Magnitude 0.0 are regarded as equal in value regardless of the orientation attribute.
Dim INVALID The space dimensionality of this class, it is derived from Orientation

8.9.3.76.2 Entity inheritance

dot_inheritance IfcVector IfcVector IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcVector->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.9.3.76.3 Formal representations

ENTITY IfcVector
 SUBTYPE OF (IfcGeometricRepresentationItem);
	Orientation : IfcDirection;
	Magnitude : IfcLengthMeasure;
 DERIVE
	 Dim : IfcDimensionCount := Orientation.Dim;
 WHERE
	MagGreaterOrEqualZero : Magnitude >= 0.0;
END_ENTITY;