IfcAxis1Placement

Definition from ISO/CD 10303-42:1992: The direction and location in three dimensional space of a single axis. An axis1_placement is defined in terms of a locating point (inherited from placement supertype) and an axis direction: this is either the direction of axis or defaults to (0.0,0.0,1.0). The actual direction for the axis placement is given by the derived attribute z (Z).

NOTE: Corresponding STEP name: axis1_placement, please refer to ISO/IS 10303-42:1994, p. 28 for the final definition of the formal standard.

HISTORY: New entity in IFC Release 1.5

Illustration:

Definition of the IfcAxis1Placement within the three-dimensional coordinate system.

EXPRESS specification:

ENTITY IfcAxis1Placement

SUBTYPE OF (

IfcPlacement);

Axis

OPTIONAL IfcDirection;

DERIVE

IfcDirection := NVL (IfcNormalise(Axis), IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcDirection([0.0,0.0,1.0]));

WHERE

WR1	:	(NOT (EXISTS (Axis))) OR (Axis.Dim = 3);
WR2	:	SELF\IfcPlacement.Location.Dim = 3;

END_ENTITY;

Attribute definitions:

Axis	:	The direction of the local Z axis.
Z	:	The normalized direction of the local Z axis. It is either identical with the Axis value, if given, or it defaults to [0.,0.,1.]

Formal Propositions:

WR1	:	The Axis when given should only reference a three-dimensional IfcDirection.
WR2	:	The Cartesian point defining the Location shall have the dimensionality of 3.

Inheritance graph

ENTITY IfcAxis1Placement;

ENTITY IfcRepresentationItem;

INVERSE

LayerAssignments

SET OF IfcPresentationLayerAssignment FOR AssignedItems;

StyledByItem

SET [0:1] OF IfcStyledItem FOR Item;

ENTITY IfcGeometricRepresentationItem;

ENTITY IfcPlacement;

Location

IfcCartesianPoint;

DERIVE

Dim

IfcDimensionCount := Location.Dim;

ENTITY IfcAxis1Placement;

Axis

OPTIONAL IfcDirection;

DERIVE

IfcDirection := NVL (IfcNormalise(Axis), IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcDirection([0.0,0.0,1.0]));

END_ENTITY;