IfcSurfaceCurveSweptAreaSolid

Definition from ISO/DIS 10303-42:1999(E): A surface curve swept area solid is a type of swept area solid which is the result of sweeping a face along a Directrix lying on a ReferenceSurface. The orientation of the SweptArea is related to the direction of the surface normal.

The SweptArea is required to be a curve bounded surface lying in the plane z = 0 and this is swept along the Directrix in such a way that the origin of the local coordinate system used to define the SweptArea is on the Directrix and the local x-axis is in the direction of the normal to the ReferenceSurface at the current point. The resulting solid has the property that the cross section of the surface by the normal plane to the Directrix at any point is a copy of the SweptArea.

The orientation of the SweptArea as it sweeps along the Directrix is precisely defined by a CartesianTransformationOperator3d with attributes:

- LocalOrigin as point (0; 0; 0),
- Axis1 as the normal N to the ReferenceSurface at the point of the Directrix with parameter u.
- Axis3 as the direction of the tangent vector t at the point of the Directrix with parameter u.
  The remaining attributes are defaulted to define a corresponding transformation matrix T(u), which varies with the Directrix parameter u.

> NOTE: The geometric shape of the solid is not dependent upon the curve parameterization; the volume depends upon the area swept and the length of the Directrix.

Definition from IAI: The swept face is given by IfcProfileDef (or subtypes), the profile definition is given within a 2D coordinate system, which is inserted into the XY plane of the Position coordinate system inherited from the supertype IfcSweptAreaSolid. The attributes of the CartesianTransformationOperator3d (as given above) should apply to the Position coordinate system, in which the profile is inserted.

> NOTE: Corresponding STEP entity: surface_curve_swept_area_solid. Please refer to ISO/DIS 10303-42:1999(E), p. 274 for the final definition of the formal standard.

> HISTORY: New entity in Release IFC2x Edition 2.

Informal propositions:

1. The SweptArea shall lie in the plane z = 0.
2. The directrix shall lie on the ReferenceSurface.

EXPRESS specification:

ENTITY IfcSurfaceCurveSweptAreaSolid
SUBTYPE OF ( | IfcSweptAreaSolid);
Directrix | : | IfcCurve;
StartParam | : | IfcParameterValue;
EndParam | : | IfcParameterValue;
ReferenceSurface | : | IfcSurface;
END_ENTITY;

Attribute definitions:

Directrix | : | The curve used to define the sweeping operation. The solid is generated by sweeping the SELF\IfcSweptAreaSolid.SweptArea along the Directrix.
StartParam | : | The parameter value on the Directrix at which the sweeping operation commences.
EndParam | : | The parameter value on the Directrix at which the sweeping operation ends.
ReferenceSurface | : | The surface containing the Directrix.

Inheritance graph

ENTITY IfcSurfaceCurveSweptAreaSolid;
ENTITY IfcRepresentationItem;
INVERSE
LayerAssignments | : | SET OF IfcPresentationLayerAssignment FOR AssignedItems;
StyledByItem | : | SET [0:1] OF IfcStyledItem FOR Item;
ENTITY IfcGeometricRepresentationItem;
ENTITY IfcSolidModel;
DERIVE
Dim | : | IfcDimensionCount := 3;
ENTITY IfcSweptAreaSolid;
SweptArea | : | IfcProfileDef;
Position | : | IfcAxis2Placement3D;
ENTITY IfcSurfaceCurveSweptAreaSolid;
Directrix | : | IfcCurve;
StartParam | : | IfcParameterValue;
EndParam | : | IfcParameterValue;
ReferenceSurface | : | IfcSurface;
END_ENTITY;