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.
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 u~1~ = u1, u~2~ = u2, v~1~ = v1 and v~2~ = 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 |u~2~ - u~1~| and 0 to|v~2~-v~1~|. If the surface is closed in a given parametric direction, the values of u~2~ or v~2~ may require to be increased by the cyclic range. 370 degrees is equivalent to 10 degrees, for those surfaces whose parametric form is defined using circular functions (sine and cosine). Entity adapted from rectangular_trimmed_surface in ISO 10303-42. New entity in IFC2x.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
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- IfcSurface
- IfcAnnotationFillArea
- IfcBooleanResult
- IfcBoundingBox
- IfcCartesianPointList
- IfcCartesianTransformationOperator
- IfcCsgPrimitive3D
- IfcCurve
- IfcDirection
- IfcFaceBasedSurfaceModel
- IfcFillAreaStyleHatching
- IfcFillAreaStyleTiles
- IfcGeometricSet
- IfcHalfSpaceSolid
- IfcLightSource
- IfcPlacement
- IfcPlanarExtent
- IfcPoint
- IfcSectionedSpine
- IfcSegment
- IfcShellBasedSurfaceModel
- IfcSolidModel
- IfcTessellatedItem
- IfcTextLiteral
- IfcVector
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. The inverse attribute LayerAssignments has been added. 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. The inverse attribute StyledByItem has been added. |
|
| IfcSurface (1) | |||
| * | Dim | IfcDimensionCount |
This attribute is formally derived. The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item. 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. |
8.9.3.55.4 Formal propositions
| Name | Description |
|---|---|
| U1AndU2Different |
U1 and U2 shall have different values. |
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| UsenseCompatible |
With exception of those surfaces closed in the U parameter, direction Usense shall be compatible with the ordered parameter values for U. |
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| V1AndV2Different |
V1 and V2 shall have different values. |
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| VsenseCompatible |
Vsense shall be compatible with the ordered parameter values for V. |
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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_bc7847cd.IFCELEMENTARYSURFACE' IN TYPEOF(BasisSurface)) AND
(NOT ('IFC4X3_DEV_bc7847cd.IFCPLANE' IN TYPEOF(BasisSurface)))) OR
('IFC4X3_DEV_bc7847cd.IFCSURFACEOFREVOLUTION' IN TYPEOF(BasisSurface)) OR
(Usense = (U2 > U1));
V1AndV2Different : V1 <> V2;
VsenseCompatible : Vsense = (V2 > V1);
END_ENTITY;