ifc-syntax-geometry-swept-solid

name	ifc-syntax-geometry-swept-solid
description	Use when you need to build, read, or debug parametric solid geometry in an IFC model : extruding a profile into a wall or slab, revolving a profile into an arch, sweeping a profile along a curve, or modelling a pipe or rebar as a swept disk, and when deciding the RepresentationType label for the shape. Prevents feeding a CURVE-type (open) profile into a solid sweep, an extrusion direction perpendicular to Z, a revolution axis outside the XY plane, an unbounded directrix with no parameters, an InnerRadius larger than the Radius, and mislabelling an advanced sweep as plain SweptSolid. Covers IfcSweptAreaSolid, IfcExtrudedAreaSolid, IfcRevolvedAreaSolid, IfcExtrudedAreaSolidTapered, IfcRevolvedAreaSolidTapered, IfcDirectrixCurveSweptAreaSolid, IfcSurfaceCurveSweptAreaSolid, IfcFixedReferenceSweptAreaSolid, IfcSweptDiskSolid, the SweptArea / Position / ExtrudedDirection / Depth / Axis / Angle / Directrix / Radius attributes, the WHERE rules, the SweptSolid versus AdvancedSweptSolid mapping, and IFC2x3 / IFC4 / IFC4.3 version differences. Keywords: IFC swept solid, IfcExtrudedAreaSolid, IfcSweptAreaSolid, IfcRevolvedAreaSolid, IfcSweptDiskSolid, IfcSurfaceCurveSweptAreaSolid, IfcFixedReferenceSweptAreaSolid, IfcDirectrixCurveSweptAreaSolid, ExtrudedDirection, SweptArea, Directrix, extrude a profile, revolve a profile, sweep along a curve, pipe geometry, rebar geometry, SweptSolid, AdvancedSweptSolid, ValidExtrusionDirection, how do I model a wall solid, wall has no geometry, solid is flat, extrusion failed, IFC2x3, IFC4, IFC4.3.
license	MIT
compatibility	Designed for Claude Code. Requires IFC IFC2x3, IFC4, IFC4.3.
metadata	{"author":"OpenAEC-Foundation","version":"1.0"}

IFC Syntax : Swept Solid Geometry

IFC carries most building geometry parametrically : a 2D cross-section (a profile) is swept through 3D space to form a solid. This skill covers the swept-solid entities, their attributes, their WHERE rules, and how the result maps to a shape representation.

Applies to IFC2x3, IFC4, and IFC4.3. The directrix family was restructured across versions : see Version Differences.

Quick Reference

The swept-solid idea

A swept solid pairs a profile with a sweep operation. The profile is the cross-section ; the sweep moves it. The profile entities (IfcProfileDef and its subtypes) are covered by ifc-syntax-geometry-profiles ; this skill covers the sweep.

A profile (IfcProfileDef, ProfileType = AREA)
        +
A sweep operation (extrude / revolve / sweep along a curve)
        =
A solid  -->  placed in an IfcShapeRepresentation, type SweptSolid or AdvancedSweptSolid

IfcSweptAreaSolid : the abstract supertype

Verified verbatim (IFC4.3) :

ENTITY IfcSweptAreaSolid
 ABSTRACT SUPERTYPE OF (ONEOF
	(IfcDirectrixCurveSweptAreaSolid
	,IfcExtrudedAreaSolid
	,IfcRevolvedAreaSolid))
 SUBTYPE OF (IfcSolidModel);
	SweptArea : IfcProfileDef;
	Position : OPTIONAL IfcAxis2Placement3D;
 WHERE
	SweptAreaType : SweptArea.ProfileType = IfcProfileTypeEnum.Area;
END_ENTITY;

Supertype chain : IfcRepresentationItem to IfcGeometricRepresentationItem to IfcSolidModel to IfcSweptAreaSolid.

• SweptArea : the profile (the cross-section).
• Position : an OPTIONAL IfcAxis2Placement3D that repositions the solid.
• SweptAreaType rule : the profile MUST have ProfileType = AREA.

ALWAYS give an IfcSweptAreaSolid a profile whose ProfileType is AREA. NEVER sweep a CURVE-type profile into a solid : a CURVE profile sweeps a surface, not a solid, and SweptAreaType rejects it.

IfcExtrudedAreaSolid : the workhorse

The most common solid in any IFC model : walls, slabs, beams, columns, footings. Verified verbatim (IFC4.3) :

ENTITY IfcExtrudedAreaSolid
 SUPERTYPE OF (ONEOF
	(IfcExtrudedAreaSolidTapered))
 SUBTYPE OF (IfcSweptAreaSolid);
	ExtrudedDirection : IfcDirection;
	Depth : IfcPositiveLengthMeasure;
 WHERE
	ValidExtrusionDirection : IfcDotProduct(IfcRepresentationItem() ||
		IfcGeometricRepresentationItem() || IfcDirection([0.0,0.0,1.0]),
		SELF.ExtrudedDirection) <> 0.0;
END_ENTITY;