8.9.3.3 IfcAxis2Placement3D
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.
The RefDirection does not have to be orthogonal to Axis.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.].
Figure 8.9.3.3.A illustrates the definition of the IfcAxis2Placement3D within the three-dimensional coordinate system.
Definition according to ISO/CD 10303-42:1992 The location and orientation in three dimensional space of three mutually perpendicular axes. An axis2_placement_3D is defined in terms of a point (inherited from placement supertype) and two (ideally orthogonal) axes. It can be used to locate and orientate a non axi-symmetric object in space and to define a placement coordinate system. The entity includes a point which forms the origin of the placement coordinate system. Two direction vectors are required to complete the definition of the placement coordinate system. The axis is the placement Z axis direction and the ref_direction is an approximation to the placement X axis direction. Entity adapted from axis2_placement_3d defined in ISO10303-42. New entity in IFC1.5.8.9.3.3.2 Entity inheritance
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- IfcPlacement
- IfcAnnotationFillArea
- IfcBooleanResult
- IfcBoundingBox
- IfcCartesianPointList
- IfcCartesianTransformationOperator
- IfcCsgPrimitive3D
- IfcCurve
- IfcDirection
- IfcFaceBasedSurfaceModel
- IfcFillAreaStyleHatching
- IfcFillAreaStyleTiles
- IfcGeometricSet
- IfcHalfSpaceSolid
- IfcLightSource
- IfcPlanarExtent
- IfcPoint
- IfcSectionedSpine
- IfcSegment
- IfcShellBasedSurfaceModel
- IfcSolidModel
- IfcSurface
- IfcTessellatedItem
- IfcTextLiteral
- IfcVector
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. The inverse attribute LayerAssignments has been added. The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed. |
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| 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. The inverse attribute StyledByItem has been added. |
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| 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. 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. The normalized directions of the placement X Axis (P[1]) and the placement Y Axis (P[2]) and the placement Z Axis (P[3]). |
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. |
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| AxisIs3D |
The Axis when given should only reference a three-dimensional IfcDirection. |
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| AxisToRefDirPosition |
The Axis and RefDirection shall not be parallel or anti-parallel. |
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| LocationIs3D |
The dimensionality of the placement location shall be 3. |
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| LocationIsCP |
No description available. |
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| RefDirIs3D |
The RefDirection when given should only reference a three-dimensional IfcDirection. |
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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_DEV_bc7847cd.IFCCARTESIANPOINT' IN TYPEOF(SELF\IfcPlacement.Location);
RefDirIs3D : (NOT (EXISTS (RefDirection))) OR (RefDirection.Dim = 3);
END_ENTITY;