IFC 4.3.x development

8.8.3.29 IfcRevolvedAreaSolid

Change log

IFC4

additionswhere_rulesAxisDirectionInXY
additionswhere_rulesAxisStartInXY
deletionswhere_rulesWR31
deletionswhere_rulesWR32

8.8.3.29.1 Semantic definitions at the entity

An IfcRevolvedAreaSolid is a solid created by revolving a cross section provided by a profile definition about an axis.

The resulting solid is positioned by the IfcSweptAreaSolid.Position relative to the object coordinate system. If provided, it allows to reposition the revolved solid. If not provided, it defaults to the current object coordinate system. The axis and the cross section shall be in the same plane, prior to any repositioning.

NOTE  Both the axis and the cross section are required to lie in the xy plane of the object position coordinate system.

revolved area solid
EXAMPLE  Figure 1 illustrates geometric parameters of the revolved solid. The revolved area solid defines the revolution of a 2D area (given by a profile definition) by an axis and angle. The result is a solid. The swept area is given by a profile definition.
  • The profile is defined:
    • as a 2D primitive, here IfcRectangleProfileDef, that is placed relative to the xy plane of object coordinate system
    • since no 2D profile position coordinate system is provided, here IfcParameterizedProfileDef.Position = NIL, the profile is positioned without transformation into the xy plane of the object coordinate system (by default, centric at 0.,0. with no rotation)
  • The resulting swept solid is not repositioned, as no position coordinate system is provided, here IfcSweptAreaSolid.Position = NIL.
The AxisLine can have any orientation within the XY plane, it does not have to be parallel to the y-axis as shown in the illustration.

Figure 1 — Revolved area solid geometry

revolved area solid
EXAMPLE  Figure 1 illustrates geometric parameters and additional positioning parameters of the revolved area solid. The revolved area solid defines the rotation of a 2D area by an axis and angle. The 2D area, provided by a parameterized profile definition, can be positioned relative to the object coordinate system (other then by default at 0.,0. with no rotation). The result is a solid that can be repositioned within the object coordinate system.
  • The profile to be swept is defined:
    • as a 2D primitive, here IfcRectangleProfileDef, that is placed relative to the xy plane of object coordinate system
    • a 2D profile position coordinate system is provided that positions the profile relative to the xy plane (here at a corner of the rectangle)
  • The resulting swept solid is repositioned, here it is moved into local z and rotated by 15' along the x axis.

Figure 2 — Repositioned revolved area solid geometry

NOTE  Definition according to ISO/CD 10303-42:1992
A revolved area solid is a solid formed by revolving a planar bounded surface about an axis. The axis shall be in the plane of the surface and the axis shall not intersect the interior of the bounded surface. The bounded surface may have holes which will sweep into holes in the solid. The direction of revolution is clockwise when viewed along the axis in the positive direction. More precisely if A is the axis location and d is the axis direction and C is an arc on the surface of revolution generated by an arbitrary point p on the boundary of the swept area, then C leaves p in direction d x (p - A) as the area is revolved.

NOTE  Entity adapted from revolved_area_solid defined in ISO 10303-42.

HISTORY  New entity in IFC1.5

Informal Propositions:

  1. The AxisLine shall lie in the plane of the SweptArea (as defined at supertype IfcSweptAreaSolid).
  2. The AxisLine shall not intersect the interior of the SweptArea (as defined at supertype IfcSweptAreaSolid).
  3. The Angle shall be between 0° and 360°, or 0 and 2π (depending on the unit type for IfcPlaneAngleMeasure).

Texture Use Definition

For side faces, textures are aligned facing upright along the sides with origin at the first point of an arbitrary profile, and following the outer bound of the profile counter-clockwise (as seen from above). For parameterized profiles, the origin is defined at the +Y extent for rounded profiles (having no sharp edge) and the first sharp edge counter-clockwise from the +Y extent for all other profiles. Textures are stretched or repeated on each side along the outer boundary of the profile according to RepeatS. Textures are stretched or repeated on each side along the outermost (longest) revolution path according to RepeatT, where coordinates are compressed towards the axis of revolution.

For top and bottom caps, textures are aligned facing front-to-back, with the origin at the minimum X and Y extent. Textures are stretched or repeated on the top and bottom to the extent of each face according to RepeatS and RepeatT.

For profiles with voids, textures are aligned facing upright along the inner side with origin at the first point of an arbitrary profile, and following the inner bound of the profile clockwise (as seen from above). For parameterized profiles, the origin of inner sides is defined at the +Y extent for rounded profiles (having no sharp edge such as hollow ellipses or rounded rectangles) and the first sharp edge clockwise from the +Y extent for all other profiles.

texture
Figure 3 illustrates default texture mapping with a repeated texture (RepeatS=True and RepeatT=True). The image on the left shows the texture where the S axis points to the right and the T axis points up. The image on the right shows the texture applied to the geometry where the X axis points back to the right, the Y axis points back to the left, and the Z axis points up. For an IfcRevolvedAreaSolid having a profile of IfcTShapeProfileDef and revolved at 22.5 degrees, the side texture coordinate origin is the first corner counter-clockwise from the +Y axis, which equals

(-0.5*IfcTShapeProfileDef.OverallWidth, +0.5*IfcTShapeProfileDef.OverallDepth),

while the top (end cap) texture coordinates start at

(-0.5*IfcTShapeProfileDef.OverallWidth, -0.5*IfcTShapeProfileDef.OverallDepth).

Figure 3 — Revolved area solid textures

8.8.3.29.1 Attributes

# Attribute Type Description
IfcRepresentationItem
LayerAssignmentSET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItemsAssignment 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.



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.



> IFC2x3 CHANGE  The inverse attribute StyledByItem has been added.

IfcGeometricRepresentationItem
IfcSolidModel
Dim INVALID The space dimensionality of this class, it is always 3.
IfcSweptAreaSolid
1 SweptArea IfcProfileDef The surface defining the area to be swept. It is given as a profile definition within the xy plane of the position coordinate system.
2 Position OPTIONAL IfcAxis2Placement3D Position coordinate system for the resulting swept solid of the sweeping operation. The position coordinate system allows for re-positioning of the swept solid. If not provided, the swept solid remains within the position as determined by the cross section or by the directrix used for the sweeping operation.

> IFC4 CHANGE  The attribute has been changed to OPTIONAL with upward compatibility for file-based exchange.
IfcRevolvedAreaSolid
3 Axis IfcAxis1Placement Axis about which revolution will take place.
4 Angle IfcPlaneAngleMeasure The angle through which the sweep will be made. This angle is measured from the plane of the swept area provided by the XY plane of the position coordinate system.
AxisLine INVALID The line of the axis of revolution.

8.8.3.29.2 Entity inheritance

dot_inheritance IfcRevolvedAreaSolidTapered IfcRevolvedAreaSolidTapered IfcRevolvedAreaSolid IfcRevolvedAreaSolid IfcRevolvedAreaSolidTapered->IfcRevolvedAreaSolid IfcSweptAreaSolid IfcSweptAreaSolid IfcRevolvedAreaSolid->IfcSweptAreaSolid IfcExtrudedAreaSolid IfcExtrudedAreaSolid IfcExtrudedAreaSolid->IfcSweptAreaSolid IfcSolidModel IfcSolidModel IfcSweptAreaSolid->IfcSolidModel IfcDirectrixCurveSweptAreaSolid IfcDirectrixCurveSweptAreaSolid IfcDirectrixCurveSweptAreaSolid->IfcSweptAreaSolid IfcSolidModel_children 4 more... IfcSolidModel_children->IfcSolidModel IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcSolidModel->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.8.3.29.3 Formal representations

ENTITY IfcRevolvedAreaSolid
 SUPERTYPE OF (ONEOF
	(IfcRevolvedAreaSolidTapered))
 SUBTYPE OF (IfcSweptAreaSolid);
	Axis : IfcAxis1Placement;
	Angle : IfcPlaneAngleMeasure;
 DERIVE
	 AxisLine : IfcLine := IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcCurve() || IfcLine(Axis.Location, 
  IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcVector(Axis.Z,1.0));
 WHERE
	AxisStartInXY : Axis.Location.Coordinates[3] = 0.0;
	AxisDirectionInXY : Axis.Z.DirectionRatios[3] = 0.0;
END_ENTITY;