IfcRectangularTrimmedSurface

BACnet MVD

#### IfcRectangularTrimmedSurface

Natural language names

| Rechteckig begrenzte Oberfläche
| Rectangular Trimmed Surface

Change log

Item | SPF | XML | Change | Description
--- | --- | --- | --- | ---
IFC4 Addendum 1
IfcRectangularTrimmedSurface |  |  |  |
Usense |  |  | MODIFIED | Type changed from BOOLEAN to IfcBoolean.
Vsense |  |  | MODIFIED | Type changed from BOOLEAN to IfcBoolean.

##### Semantic definitions at the entity

Entity 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.

> NOTE Definition according to ISO/CD 10303-42:1992
> The trimmed surface is a simple bounded surface in which the boundaries are the constant parametric lines u1 = u1, u2 = u2, v1 = v1 and v2 = v2. All these values shall be within the parametric range of the referenced surface. Cyclic properties of the parameter range are assumed. The rectangular trimmed surface inherits its parameterization directly from the basis surface and has parameter ranges from 0 to |u2 - u1| and 0 to|v2-v1|.

> NOTE If the surface is closed in a given parametric direction, the values of u2 or v2 may require to be increased by the cyclic range.

> EXAMPLE 370 degrees is equivalent to 10 degrees, for those surfaces whose parametric form is defined using circular functions (sine and cosine).

> NOTE Entity adapted from rectangular_trimmed_surface in ISO 10303-42.

> HISTORY New entity in IFC2x.

Informal Propositions:

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

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
1 | BasisSurface | IfcSurface |  | Surface being trimmed. |  | X
2 | U1 | IfcParameterValue |  | First u parametric value. |  | X
3 | V1 | IfcParameterValue |  | First v parametric value. |  | X
4 | U2 | IfcParameterValue |  | Second u parametric value. |  | X
5 | V2 | IfcParameterValue |  | Second v parametric value. |  | X
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. |  | X
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. |  | X

Formal Propositions

Rule | Description
--- | ---
U1AndU2Different | U1 and U2 shall have different values.
V1AndV2Different | V1 and V2 shall have different values.
UsenseCompatible | With exception of those surfaces closed in the U parameter, direction Usense shall be compatible with the ordered parameter values for U.
VsenseCompatible | Vsense shall be compatible with the ordered parameter values for V.

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
IfcRepresentationItem

LayerAssignment

IfcPresentationLayerAssignment
@AssignedItems

S[0:1]

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.

X

StyledByItem

IfcStyledItem
@Item

S[0:1]

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.

X

X

IfcGeometricRepresentationItem
IfcSurface

Dim
:=3

IfcDimensionCount

The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item.

> IFC4 CHANGE Derived attribute promoted from subtypes.

X

X

IfcBoundedSurface
IfcRectangularTrimmedSurface
1 | BasisSurface | IfcSurface |  | Surface being trimmed. |  | X
2 | U1 | IfcParameterValue |  | First u parametric value. |  | X
3 | V1 | IfcParameterValue |  | First v parametric value. |  | X
4 | U2 | IfcParameterValue |  | Second u parametric value. |  | X
5 | V2 | IfcParameterValue |  | Second v parametric value. |  | X
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. |  | X
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. |  | X

##### Formal representations

XML Specification
`<xs:element name="IfcRectangularTrimmedSurface" type="ifc:IfcRectangularTrimmedSurface" substitutionGroup="ifc:IfcBoundedSurface" nillable="true"/>
<xs:complexType name="IfcRectangularTrimmedSurface">
<xs:complexContent>
<xs:extension base="ifc:IfcBoundedSurface">
<xs:sequence>
<xs:element name="BasisSurface" type="ifc:IfcSurface" nillable="true"/>
</xs:sequence>
<xs:attribute name="U1" type="ifc:IfcParameterValue" use="optional"/>
<xs:attribute name="V1" type="ifc:IfcParameterValue" use="optional"/>
<xs:attribute name="U2" type="ifc:IfcParameterValue" use="optional"/>
<xs:attribute name="V2" type="ifc:IfcParameterValue" use="optional"/>
<xs:attribute name="Usense" type="ifc:IfcBoolean" use="optional"/>
<xs:attribute name="Vsense" type="ifc:IfcBoolean" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcRectangularTrimmedSurface
SUBTYPE OF (IfcBoundedSurface);
BasisSurface : IfcSurface;
U1 : IfcParameterValue;
V1 : IfcParameterValue;
U2 : IfcParameterValue;
V2 : IfcParameterValue;
Usense : IfcBoolean;
Vsense : IfcBoolean;
WHERE
U1AndU2Different : U1 <> U2;
V1AndV2Different : V1 <> V2;
UsenseCompatible : (('IFCGEOMETRYRESOURCE.IfcElementarySurface' IN TYPEOF(BasisSurface)) AND
(NOT ('IFCGEOMETRYRESOURCE.IfcPlane' IN TYPEOF(BasisSurface)))) OR
('IFCGEOMETRYRESOURCE.IfcSurfaceOfRevolution' IN TYPEOF(BasisSurface)) OR
(Usense = (U2 > U1));
VsenseCompatible : Vsense = (V2 > V1);
END_ENTITY;

EXPRESS-G diagram

`

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