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Swept Disk Solid |

Item | SPF | XML | Change | Description |
---|---|---|---|---|

4.0.0.0 |
||||

IfcSweptDiskSolid | ||||

StartParam | MODIFIED | Instantiation changed to OPTIONAL. | ||

EndParam | MODIFIED | Instantiation changed to OPTIONAL. |

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 non-tangent continuous segments.

Figure 166 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*

NOTE Although the example shows aDirectrixas a poly curve on a planar reference surface, the definition of IfcSweptDiskSolid is not restricted to be based on planer curves. However view definitions or implementer agreements may provide restrictions.

NOTE The geometric item IfcIndexedPolyCurve provides a more compact representation compared withIfcCompositeCurveas is therefore the prefered curve representation for theDirectrix.

Figure 166 — Swept disk solid geometry |

NOTE Definition according to ISO/CD 10303-42:1992

A swept disk solid is the solid produced by sweeping a circular disk along a three dimensional curve. During the sweeping operation the normal to the plane of the circular disk is in the direction of the tangent to the directrix curve and the center of the disk lies on the directrix. The circular disk may, optionally, have a central hole, in this case the resulting solid has a through hole, or, an internal void when the directrix forms a close curve.

NOTE Entity adapted fromswept_disk_soliddefined in ISO 10303-42.

HISTORY New entity in IFC2x2.

IFC4 CHANGE The attributeStartParamandEndParamhave been made optional.

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.

# | Attribute | Type | Cardinality | Description | R |
---|---|---|---|---|---|

1 | Directrix | IfcCurve |
The curve used to define the sweeping operation. The solid is generated by sweeping a circular disk along the Directrix. | X | |

2 | Radius | IfcPositiveLengthMeasure |
The Radius of the circular disk to be swept along the directrix. Denotes the outer radius, if an InnerRadius is applied. | X | |

3 | InnerRadius | IfcPositiveLengthMeasure | ? | This attribute is optional, if present it defines the radius of a circular hole in the centre of the disk. | X |

4 | StartParam | 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..
IFC4 CHANGE The attribute has been changed to OPTIONAL with upward compatibility for file-based exchange. | X |

5 | EndParam | 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..
IFC4 CHANGE The attribute has been changed to OPTIONAL with upward compatibility for file-based exchange. | X |

Rule | Description |
---|---|

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. |

DirectrixBounded | If the values for StartParam or EndParam are omited, then the Directrix has to be a bounded or closed curve.
IFC4 CHANGE New WHERE rule. |

# | Attribute | Type | Cardinality | Description | R |
---|---|---|---|---|---|

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 IFC4 CHANGE The inverse attribute | ||

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 | X | |

IfcGeometricRepresentationItem | |||||

IfcSolidModel | |||||

Dim :=3 | IfcDimensionCount | The space dimensionality of this class, it is always 3. | X | ||

IfcSweptDiskSolid | |||||

1 | Directrix | IfcCurve |
The curve used to define the sweeping operation. The solid is generated by sweeping a circular disk along the Directrix. | X | |

2 | Radius | IfcPositiveLengthMeasure |
The Radius of the circular disk to be swept along the directrix. Denotes the outer radius, if an InnerRadius is applied. | X | |

3 | InnerRadius | IfcPositiveLengthMeasure | ? | This attribute is optional, if present it defines the radius of a circular hole in the centre of the disk. | X |

4 | StartParam | 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..
IFC4 CHANGE The attribute has been changed to OPTIONAL with upward compatibility for file-based exchange. | X |

5 | EndParam | 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..
| X |

` <xs:element name="IfcSweptDiskSolid" type="ifc:IfcSweptDiskSolid" substitutionGroup="ifc:IfcSolidModel" nillable="true"/>`

<xs:complexType name="IfcSweptDiskSolid">

<xs:complexContent>

<xs:extension base="ifc:IfcSolidModel">

<xs:sequence>

<xs:element name="Directrix" type="ifc:IfcCurve" nillable="true"/>

</xs:sequence>

<xs:attribute name="Radius" type="ifc:IfcPositiveLengthMeasure" use="optional"/>

<xs:attribute name="InnerRadius" type="ifc:IfcPositiveLengthMeasure" use="optional"/>

<xs:attribute name="StartParam" type="ifc:IfcParameterValue" use="optional"/>

<xs:attribute name="EndParam" type="ifc:IfcParameterValue" use="optional"/>

</xs:extension>

</xs:complexContent>

</xs:complexType>

```
ENTITY IfcSweptDiskSolid
```

SUBTYPE OF (IfcSolidModel)**;**

Directrix : IfcCurve;

Radius : IfcPositiveLengthMeasure;

InnerRadius : OPTIONAL IfcPositiveLengthMeasure;

StartParam : OPTIONAL IfcParameterValue;

EndParam : OPTIONAL IfcParameterValue;

WHERE

DirectrixDim : Directrix.Dim = 3;

InnerRadiusSize : (NOT EXISTS(InnerRadius)) OR (Radius > InnerRadius);

DirectrixBounded : (EXISTS(StartParam) AND EXISTS(EndParam)) OR

(SIZEOF(['IFCGEOMETRYRESOURCE.IfcConic', 'IFCGEOMETRYRESOURCE.IfcBoundedCurve'] * TYPEOF(Directrix)) = 1);

END_ENTITY;