IFC 4.3.0.1 (IFC4X3) development

8.8.3.30 IfcRevolvedAreaSolidTapered

8.8.3.30.1 Semantic definition

IfcRevolvedAreaSolidTapered is defined by revolving a cross section along a circular arc. The cross section may change along the revolving sweep from the shape of the start cross section into the shape of the end cross section. Corresponding vertices of the start and end cross sections are then connected. The bounded surface may have holes which will sweep into holes in the solid.

The rotation axis is defined by:

• Start point: SELF\IfcSweptAreaSolid.Position.Location
• Direction: SELF\IfcRevolvedAreaSolid.Axis
• Rotation axis: SELF\IfcRevolvedAreaSolid.AxisLine, created from start point and direction by applying a 1 unit magnitude.
• Orientation: Positive angles are applied clockwise when looking into the positive direction of the rotation axis.

The start cross section is defined by SELF\IfcSweptAreaSolid.SweptArea:

• A bounded planar surface lying in the XY plane of the position coordinate system defined by SELF\IfcSweptAreaSolid.Position.P[1] and SELF\IfcSweptAreaSolid.Position.P[2]
• The rotation axis lies in the plane of the start cross section but shall not intersect the interior of the start cross section.

The end cross section is defined by EndSweptArea:

• A bounded planar surface lying in the XY plane of the position coordinate system defined by rotating the start position coordinates provided by SELF\IfcSweptAreaSolid.Position around the rotation axis by the angle given by SELF\IfcRevolvedAreaSolid.Angle. *
• The end cross section is topologically similar to the start cross section (having the same number of vertices and edges).
• The end cross section can either be defined by the same paramteric profile using different parameter values, or by a 2D Cartesian transformation of the start profile within the end cross section plane.

The solid is generated by transforming the start cross section into to end cross section. A start face, an end face (each defined by start and end cross sections), and one or more lateral faces. Each lateral face is a ruled surface defined by a pair of corresponding edges of the start and end section. The ruled surfaces are constructed in the cylindrical coordinate space defined by the supertype IfcRevolvedAreaSolid.

Informal Propositions:

1. Mirroring within IfcDerivedProfileDef.Operator shall not be used

8.8.3.30.5 Formal representation

ENTITY IfcRevolvedAreaSolidTapered
SUBTYPE OF (IfcRevolvedAreaSolid);
EndSweptArea : IfcProfileDef;
WHERE
CorrectProfileAssignment : IfcTaperedSweptAreaProfiles(SELF\IfcSweptAreaSolid.SweptArea, SELF.EndSweptArea);
END_ENTITY;