8.9.3.56 IfcRectangularTrimmedSurface

8.9.3.56.1 Semantic definition

The IfcRectangularTrimmedSurface is a surface created by bounding its BasisSurface along two pairs of parallel curves defined within the parametric space of the referenced surface.

Informal Propositions:

The domain of the trimmed surface shall be within the domain of the surface being trimmed.

8.9.3.56.2 Entity inheritance

8.9.3.56.3 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.
IfcSurface (1)
*	Dim	IfcDimensionCount	This attribute is formally derived. `3` The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item. IFC4-CHANGE Derived attribute promoted from subtypes.
Click to show 3 hidden inherited attributes Click to hide 3 inherited attributes
IfcRectangularTrimmedSurface (7)
1	BasisSurface	IfcSurface	Surface being trimmed.
2	U1	IfcParameterValue	First u parametric value.
3	V1	IfcParameterValue	First v parametric value.
4	U2	IfcParameterValue	Second u parametric value.
5	V2	IfcParameterValue	Second v parametric value.
6	Usense	IfcBoolean	Flag to indicate whether the direction of the first parameter of the trimmed surface agrees with or opposes the sense of u in the basis surface.
7	Vsense	IfcBoolean	Flag to indicate whether the direction of the second parameter of the trimmed surface agrees with or opposes the sense of v in the basis surface.

Table 8.9.3.56.A

8.9.3.56.4 Formal propositions

Name	Description
U1AndU2Different	U1 and U2 shall have different values.
`U1 <> U2`
UsenseCompatible	With exception of those surfaces closed in the U parameter, direction Usense shall be compatible with the ordered parameter values for U.
`(('IFC4X3.IFCELEMENTARYSURFACE' IN TYPEOF(BasisSurface)) AND (NOT ('IFC4X3.IFCPLANE' IN TYPEOF(BasisSurface)))) OR ('IFC4X3.IFCSURFACEOFREVOLUTION' IN TYPEOF(BasisSurface)) OR (Usense = (U2 > U1))`
V1AndV2Different	V1 and V2 shall have different values.
`V1 <> V2`
VsenseCompatible	Vsense shall be compatible with the ordered parameter values for V.
`Vsense = (V2 > V1)`

Table 8.9.3.56.B

8.9.3.56.5 Formal representation

ENTITY IfcRectangularTrimmedSurface
 SUBTYPE OF (IfcBoundedSurface);
	BasisSurface : IfcSurface;
	U1 : IfcParameterValue;
	V1 : IfcParameterValue;
	U2 : IfcParameterValue;
	V2 : IfcParameterValue;
	Usense : IfcBoolean;
	Vsense : IfcBoolean;
 WHERE
	U1AndU2Different : U1 <> U2;
	UsenseCompatible : (('IFC4X3.IFCELEMENTARYSURFACE' IN TYPEOF(BasisSurface)) AND
         (NOT ('IFC4X3.IFCPLANE' IN TYPEOF(BasisSurface)))) OR
         ('IFC4X3.IFCSURFACEOFREVOLUTION' IN TYPEOF(BasisSurface)) OR
         (Usense = (U2 > U1));
	V1AndV2Different : V1 <> V2;
	VsenseCompatible : Vsense = (V2 > V1);
END_ENTITY;

8.9.3.56.6 References

IfcBoundedSurface