8.8.3.38 IfcShellBasedSurfaceModel
8.8.3.38.1 Semantic definition
An IfcShellBasedSurfaceModel represents the shape by a set of open or closed shells. The connected faces within the shell have a dimensionality 2 and are placed in a coordinate space of dimensionality 3.
Definition according to ISO/CD 10303-42:1992 A shell based surface model is described by a set of open or closed shells of dimensionality 2. The shells shall not intersect except at edges and vertices. In particular, distinct faces may not intersect. A complete face of one shell may be shared with another shell. Coincident portions of shells shall both reference the same faces, edges and vertices defining the coincident region. There shall be at least one shell. A shell may exist independently of a surface model. Entity adapted from shell_based_surface_model defined in ISO 10303-42. New entity in IFC2x.Informal Propositions
- The dimensionality of the shell based surface model is 2.
- The shells shall not overlap or intersect except at common faces, edges or vertices.
8.8.3.38.2 Entity inheritance
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- IfcShellBasedSurfaceModel
- IfcAnnotationFillArea
- IfcBooleanResult
- IfcBoundingBox
- IfcCartesianPointList
- IfcCartesianTransformationOperator
- IfcCsgPrimitive3D
- IfcCurve
- IfcDirection
- IfcFaceBasedSurfaceModel
- IfcFillAreaStyleHatching
- IfcFillAreaStyleTiles
- IfcGeometricSet
- IfcHalfSpaceSolid
- IfcLightSource
- IfcPlacement
- IfcPlanarExtent
- IfcPoint
- IfcSectionedSpine
- IfcSegment
- IfcSolidModel
- IfcSurface
- IfcTessellatedItem
- IfcTextLiteral
- IfcVector
8.8.3.38.3 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. |
|
| Click to show 2 hidden inherited attributes Click to hide 2 inherited attributes | |||
| IfcShellBasedSurfaceModel (2) | |||
| 1 | SbsmBoundary | SET [1:?] OF IfcShell |
No description available. |
| * | Dim | IfcDimensionCount |
This attribute is formally derived. The space dimensionality of this class, it is always 3. |
8.8.3.38.4 Formal representation
ENTITY IfcShellBasedSurfaceModel
SUBTYPE OF (IfcGeometricRepresentationItem);
SbsmBoundary : SET [1:?] OF IfcShell;
DERIVE
Dim : IfcDimensionCount := 3;
END_ENTITY;