8.9.3.3 IfcAxis2Placement3D

AbRV ⓘ

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8.9.3.3.1 Semantic definition

The IfcAxis2Placement3D provides location and orientations to place items in a three-dimensional space. The attribute Axis defines the Z direction, RefDirection the X direction. The Y direction is derived.

If the attribute values for Axis and RefDirection are not given, the placement defaults to P[1] (x-axis) as [1.,0.,0.], P[2] (y-axis) as [0.,1.,0.] and P[3] (z-axis) as [0.,0.,1.].

axis2 placement 2D — Figure 8.9.3.3.A — Axis2 placement 3D

Figure 8.9.3.3.A illustrates the definition of the IfcAxis2Placement3D within the three-dimensional coordinate system.

8.9.3.3.2 Entity inheritance

8.9.3.3.3 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.
IfcPlacement (2)
1	Location	IfcPoint	The geometric position of a reference point, such as the center of a circle, of the item to be located.
*	Dim	IfcDimensionCount	This attribute is formally derived. `Location.Dim` The space dimensionality of this class, derived from the dimensionality of the location.
Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes
IfcAxis2Placement3D (3)
2	Axis	OPTIONAL IfcDirection	The exact direction of the local Z Axis.
3	RefDirection	OPTIONAL IfcDirection	The direction used to determine the direction of the local X Axis. If necessary an adjustment is made to maintain orthogonality to the Axis direction. If Axis and/or RefDirection is omitted, these directions are taken from the geometric coordinate system.
*	P	LIST [3:3] OF IfcDirection	This attribute is formally derived. `IfcBuildAxes(Axis, RefDirection)` The normalized directions of the placement X Axis (P[1]) and the placement Y Axis (P[2]) and the placement Z Axis (P[3]).

Table 8.9.3.3.B

8.9.3.3.4 Formal propositions

Name	Description
AxisAndRefDirProvision	Either both, Axis and RefDirection are not given and therefore defaulted, or both shall be given.
`NOT ((EXISTS (Axis)) XOR (EXISTS (RefDirection)))`
AxisIs3D	The Axis when given should only reference a three-dimensional IfcDirection.
`(NOT (EXISTS (Axis))) OR (Axis.Dim = 3)`
AxisToRefDirPosition	The Axis and RefDirection shall not be parallel or anti-parallel.
`(NOT (EXISTS (Axis))) OR (NOT (EXISTS (RefDirection))) OR (IfcCrossProduct(Axis,RefDirection).Magnitude > 0.0)`
LocationIs3D	The dimensionality of the placement location shall be 3.
`SELF\IfcPlacement.Location.Dim = 3`
LocationIsCP	No description available.
`'IFC4X3_ADD2.IFCCARTESIANPOINT' IN TYPEOF(SELF\IfcPlacement.Location)`
RefDirIs3D	The RefDirection when given should only reference a three-dimensional IfcDirection.
`(NOT (EXISTS (RefDirection))) OR (RefDirection.Dim = 3)`

Table 8.9.3.3.C

8.9.3.3.5 Formal representation

ENTITY IfcAxis2Placement3D
 SUBTYPE OF (IfcPlacement);
	Axis : OPTIONAL IfcDirection;
	RefDirection : OPTIONAL IfcDirection;
 DERIVE
	 P : LIST [3:3] OF IfcDirection := IfcBuildAxes(Axis, RefDirection);
 WHERE
	AxisAndRefDirProvision : NOT ((EXISTS (Axis)) XOR (EXISTS (RefDirection)));
	AxisIs3D : (NOT (EXISTS (Axis))) OR (Axis.Dim = 3);
	AxisToRefDirPosition : (NOT (EXISTS (Axis))) OR (NOT (EXISTS (RefDirection))) OR (IfcCrossProduct(Axis,RefDirection).Magnitude > 0.0);
	LocationIs3D : SELF\IfcPlacement.Location.Dim = 3;
	LocationIsCP : 'IFC4X3_ADD2.IFCCARTESIANPOINT' IN TYPEOF(SELF\IfcPlacement.Location);
	RefDirIs3D : (NOT (EXISTS (RefDirection))) OR (RefDirection.Dim = 3);
END_ENTITY;