IfcSweptDiskSolid

Natural language names
Festkörper - Entlang einer Leitlinie extrudierte Kreisscheibe
Swept Disk Solid
Change log
ItemSPFXMLChangeDescription
IFC2x3 to IFC4
    IfcSweptDiskSolid
      StartParamMODIFIEDInstantiation changed to OPTIONAL.
      EndParamMODIFIEDInstantiation changed to OPTIONAL.
Semantic definitions at the entity
Entity 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 non-tangent continuous segments.

Figure 358 illustrates an example.

NOTE  Although the example shows a Directrix as 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 with IfcCompositeCurve as is therefore the prefered curve representation for the Directrix.
disk solid

Figure 358 — 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 from swept_disk_solid defined in ISO 10303-42.
HISTORY  New entity in IFC2x2.
IFC4 CHANGE  The attribute StartParam and EndParam have been made optional.

Informal Propositions:

  1. 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.
  2. 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
  3. The Directrix shall not be based on an intersecting curve.
Attribute definitions
#AttributeTypeCardinalityDescription G
1DirectrixIfcCurve The curve used to define the sweeping operation. The solid is generated by sweeping a circular disk along the Directrix.X
2RadiusIfcPositiveLengthMeasure The Radius of the circular disk to be swept along the directrix. Denotes the outer radius, if an InnerRadius is applied.X
3InnerRadiusIfcPositiveLengthMeasure? This attribute is optional, if present it defines the radius of a circular hole in the centre of the disk.X
4StartParamIfcParameterValue? 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
5EndParamIfcParameterValue? 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
Formal Propositions
RuleDescription
DirectrixDimThe Directrix shall be a curve in three dimensional space.
InnerRadiusSizeIf InnerRadius exists then Radius denoting the outer radius shall be greater than InnerRadius.
DirectrixBoundedIf the values for StartParam or EndParam are omited, then the Directrix has to be a bounded or closed curve.
IFC4 CHANGE  New WHERE rule.
Inherited definitions from supertypes
Entity inheritance IfcSweptDiskSolidPolygonal IfcSolidModel 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
IfcSolidModel
Dim
:=3
IfcDimensionCountThe space dimensionality of this class, it is always 3. X
IfcSweptDiskSolid
1DirectrixIfcCurve The curve used to define the sweeping operation. The solid is generated by sweeping a circular disk along the Directrix.X
2RadiusIfcPositiveLengthMeasure The Radius of the circular disk to be swept along the directrix. Denotes the outer radius, if an InnerRadius is applied.X
3InnerRadiusIfcPositiveLengthMeasure? This attribute is optional, if present it defines the radius of a circular hole in the centre of the disk.X
4StartParamIfcParameterValue? 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
5EndParamIfcParameterValue? 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
Examples
Formal representations
XML Specification
 <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>
EXPRESS Specification
ENTITY IfcSweptDiskSolid
 SUPERTYPE OF(IfcSweptDiskSolidPolygonal)
 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;

Link to EXPRESS-G diagram EXPRESS-G diagram

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