IfcRectangularTrimmedSurface

Natural language names
Rechteckig begrenzte Oberfläche
Rectangular Trimmed Surface
Change log
ItemSPFXMLChangeDescription
IFC4 Addendum 1 4.0.1.0
    IfcRectangularTrimmedSurface
      UsenseMODIFIEDType changed from BOOLEAN to IfcBoolean.
      VsenseMODIFIEDType 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
#AttributeTypeCardinalityDescription G
1BasisSurfaceIfcSurface Surface being trimmed. X
2U1IfcParameterValue First u parametric value. X
3V1IfcParameterValue First v parametric value. X
4U2IfcParameterValue Second u parametric value. X
5V2IfcParameterValue Second v parametric value. X
6UsenseIfcBoolean 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
7VsenseIfcBoolean 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
RuleDescription
U1AndU2DifferentU1 and U2 shall have different values.
V1AndV2DifferentV1 and V2 shall have different values.
UsenseCompatibleWith exception of those surfaces closed in the U parameter, direction Usense shall be compatible with the ordered parameter values for U.
VsenseCompatibleVsense shall be compatible with the ordered parameter values for V.
Inherited definitions from supertypes
Entity inheritance IfcBoundedSurface IfcSurface IfcGeometricRepresentationItem IfcRepresentationItem
Attribute inheritance
#AttributeTypeCardinalityDescriptionG
IfcRepresentationItem
LayerAssignmentIfcPresentationLayerAssignment
@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
StyledByItemIfcStyledItem
@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
IfcGeometricRepresentationItem
IfcSurface
Dim
:=3
IfcDimensionCountThe space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item.
IFC4 CHANGE Derived attribute promoted from subtypes.
X
IfcBoundedSurface
IfcRectangularTrimmedSurface
1BasisSurfaceIfcSurface Surface being trimmed. X
2U1IfcParameterValue First u parametric value. X
3V1IfcParameterValue First v parametric value. X
4U2IfcParameterValue Second u parametric value. X
5V2IfcParameterValue Second v parametric value. X
6UsenseIfcBoolean 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
7VsenseIfcBoolean 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;

Link to EXPRESS-G diagram EXPRESS-G diagram

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