8.9.3.55 IfcRectangularTrimmedSurface

8.9.3.55.1 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.

8.9.3.55.2 Entity inheritance

8.9.3.55.3 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 8.9.3.55.A

8.9.3.55.4 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_DEV_20bdb3d.IFCELEMENTARYSURFACE' IN TYPEOF(BasisSurface)) AND (NOT ('IFC4X3_DEV_20bdb3d.IFCPLANE' IN TYPEOF(BasisSurface)))) OR ('IFC4X3_DEV_20bdb3d.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 8.9.3.55.B

8.9.3.55.5 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_DEV_20bdb3d.IFCELEMENTARYSURFACE' IN TYPEOF(BasisSurface)) AND
         (NOT ('IFC4X3_DEV_20bdb3d.IFCPLANE' IN TYPEOF(BasisSurface)))) OR
         ('IFC4X3_DEV_20bdb3d.IFCSURFACEOFREVOLUTION' IN TYPEOF(BasisSurface)) OR
         (Usense = (U2 > U1));
	V1AndV2Different : V1 <> V2;
	VsenseCompatible : Vsense = (V2 > V1);
END_ENTITY;

8.9.3.55.6 References

IfcBoundedSurface