IfcGridPlacement
Definition from IAI: The IfcGridPlacement
provides a specialization of IfcObjectPlacement in
which the placement and axis direction of the object coordinate system
is defined by a reference to the design grid.
The location of the object coordinate system is given by the
attribute PlacementLocation. The axis direction (of
x-axis) of the object coordinate system is given:
- by the tangent of the first grid axis (PlacementLocation.IntersectingAxes[1])
at the virtual intersection (maybe using the offset curve, if PlacementLocation.OffsetDistances
is given) in case that the PlacementRefDirection is
not given.
- by the tangent between the virtual grid intersection of PlacementLocation
and the virtual grid intersection of PlacementRefDirection
in case that the PlacementRefDirection is given)
The direction of the y-axis of the object coordinate system is
the orthogonal complement to the x-axis. The direction of the z-axis is
the orientation of the cross product of the x-axis and the y-axis.
HISTORY:
New entity in IFC Release 1.5. The entity name was changed from
IfcConstrainedPlacement. in IFC Release 2x.
Geometry use definitions:
The following example shows the usage of placement location
and direction for an IfcGridPlacement.
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PlacementRefDirection
is not given - the object coordinate system is
defined by:
- its location: given by the virtual
grid intersection of PlacementLocation
- its x-axis direction: given by the
tangent of the first intersecting axis in the offset location of the
virtual grid intersection
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PlacementRefDirection
is given - the object coordinate system is defined by:
- its location: given by the virtual
grid intersection of PlacementLocation
- its x-axis direction: given by the
tangent of the line between the virtual grid intersection of the PlacementLocation
and the virtual grid intersection of the PlacementRefDirection.
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EXPRESS specification:
Attribute definitions:
PlacementLocation
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A constraint on one or both ends of the path for an ExtrudedSolid.
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PlacementRefDirection
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Reference to a second grid axis intersection, which defines the orientation of the grid placement.
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Inheritance graph
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PlacesObject
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SET [1:1] OF IfcProduct FOR ObjectPlacement;
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