8.8.3.42 IfcSweptDiskSolid
8.8.3.42.1 Semantic definition
An IfcSweptDiskSolid represents the 3D shape by a sweeping representation scheme allowing a two dimensional circularly bounded plane to sweep along a three dimensional Directrix through space.
The StartParam and EndParam parameter are optional, if not provided they default to the start and end of the Directrix. Only if the Directrix is given by a bounded or by a closed curve, it is permissible to omit the values of StartParam and EndParam.
If the transitions between consecutive segments of the Directrix are not tangent continuous, the resulting solid is created by a miter at half angle between the two segments. Informal proposition restricts the permissible angle between two nontangent continuous segments.
Figure 8.8.3.42.A illustrates an example.
 Directrix given as IfcIndexedPolyCurve, having linear and circular arc segments, that are tangent continuous between each segments
 Directrix being a bounded and open curve
 No StartParam and EndParam are provided, start and end default to start and end of the bounded curve of the Directrix
Informal Propositions:
 If the Directrix curve definition is not tangent continuous, the transition between the segments has to be within an acceptable limit of tangent discontinuity. Very sharp edges may result in nearly impossible miter. Implementer agreements may define acceptable limits for tangent discontinuity.
 The segments of the Directrix shall be long enough to apply the Radius. In case of an arc segment forming part of the Directrix, its radius shall be greater then the disk Radius
 The Directrix shall not be based on an intersecting curve.
8.8.3.42.2 Entity inheritance

 IfcSolidModel
 IfcAnnotationFillArea
 IfcBooleanResult
 IfcBoundingBox
 IfcCartesianPointList
 IfcCartesianTransformationOperator
 IfcCsgPrimitive3D
 IfcCurve
 IfcDirection
 IfcFaceBasedSurfaceModel
 IfcFillAreaStyleHatching
 IfcFillAreaStyleTiles
 IfcGeometricSet
 IfcHalfSpaceSolid
 IfcLightSource
 IfcPlacement
 IfcPlanarExtent
 IfcPoint
 IfcSectionedSpine
 IfcSegment
 IfcShellBasedSurfaceModel
 IfcSurface
 IfcTessellatedItem
 IfcTextLiteral
 IfcVector
8.8.3.42.3 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. 

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. 

IfcSolidModel (1)  
*  Dim  IfcDimensionCount 
This attribute is formally derived.
The space dimensionality of this class, it is always 3. 
Click to show 3 hidden inherited attributes Click to hide 3 inherited attributes  
IfcSweptDiskSolid (5)  
1  Directrix  IfcCurve 
The curve used to define the sweeping operation. The solid is generated by sweeping a circular disk along the Directrix. 
2  Radius  IfcPositiveLengthMeasure 
The Radius of the circular disk to be swept along the directrix. Denotes the outer radius, if an InnerRadius is applied. 
3  InnerRadius  OPTIONAL IfcPositiveLengthMeasure 
This attribute is optional, if present it defines the radius of a circular hole in the centre of the disk. 
4  StartParam  OPTIONAL IfcParameterValue 
The parameter value on the Directrix at which the sweeping operation commences. If no value is provided the start of the sweeping operation is at the start of the Directrix. 
5  EndParam  OPTIONAL IfcParameterValue 
The parameter value on the Directrix at which the sweeping operation ends. If no value is provided the end of the sweeping operation is at the end of the Directrix. 
8.8.3.42.4 Formal propositions
Name  Description 

DirectrixBounded 
If the values for StartParam or EndParam are omitted, then the Directrix has to be a bounded or closed curve. 


DirectrixDim 
The Directrix shall be a curve in three dimensional space. 


InnerRadiusSize 
If InnerRadius exists then Radius denoting the outer radius shall be greater than InnerRadius. 

8.8.3.42.5 Formal representation
ENTITY IfcSweptDiskSolid
SUPERTYPE OF (ONEOF
(IfcSweptDiskSolidPolygonal))
SUBTYPE OF (IfcSolidModel);
Directrix : IfcCurve;
Radius : IfcPositiveLengthMeasure;
InnerRadius : OPTIONAL IfcPositiveLengthMeasure;
StartParam : OPTIONAL IfcParameterValue;
EndParam : OPTIONAL IfcParameterValue;
WHERE
DirectrixBounded : (EXISTS(StartParam) AND EXISTS(EndParam)) OR
(SIZEOF(['IFC4X3_TC1.IFCCONIC', 'IFC4X3_TC1.IFCBOUNDEDCURVE'] * TYPEOF(Directrix)) = 1);
DirectrixDim : Directrix.Dim = 3;
InnerRadiusSize : (NOT EXISTS(InnerRadius)) OR (Radius > InnerRadius);
END_ENTITY;