diff --git a/src/ifcgeom/kernels/opencascade/sweep_along_curve.cpp b/src/ifcgeom/kernels/opencascade/sweep_along_curve.cpp
new file mode 100644
index 0000000000..7505e40663
--- /dev/null
+++ b/src/ifcgeom/kernels/opencascade/sweep_along_curve.cpp
@@ -0,0 +1,157 @@
+/********************************************************************************
+ * *
+ * This file is part of IfcOpenShell. *
+ * *
+ * IfcOpenShell is free software: you can redistribute it and/or modify *
+ * it under the terms of the Lesser GNU General Public License as published by *
+ * the Free Software Foundation, either version 3.0 of the License, or *
+ * (at your option) any later version. *
+ * *
+ * IfcOpenShell is distributed in the hope that it will be useful, *
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
+ * Lesser GNU General Public License for more details. *
+ * *
+ * You should have received a copy of the Lesser GNU General Public License *
+ * along with this program. If not, see . *
+ * *
+ ********************************************************************************/
+
+#include "OpenCascadeKernel.h"
+#include "base_utils.h"
+
+#include
+#include
+#include
+#include
+#include
+#include
+
+using namespace ifcopenshell::geometry;
+using namespace ifcopenshell::geometry::kernels;
+using namespace IfcGeom;
+using namespace IfcGeom::util;
+
+bool OpenCascadeKernel::convert(const taxonomy::sweep_along_curve::ptr scs, TopoDS_Shape& result) {
+ auto w = convert_curve(scs->curve);
+ if (w.which() == 0) {
+ Logger::Error("Unsupported directrix");
+ }
+ TopoDS_Shape face;
+ convert(taxonomy::cast(scs->basis), face);
+
+ Handle(Geom_Surface) surface;
+ if (scs->surface) {
+ convert_surface(scs->surface);
+ }
+
+ gp_Trsf directrix;
+ TopoDS_Wire wire = boost::get(w);
+ TopoDS_Wire section;
+
+ const bool is_plane = surface && surface->DynamicType() == STANDARD_TYPE(Geom_Plane);
+
+ gp_Pln pln;
+ gp_Pnt directrix_origin;
+ gp_Vec directrix_tangent;
+ bool directrix_on_plane = is_plane;
+
+ if (is_plane) {
+ pln = Handle(Geom_Plane)::DownCast(surface)->Pln();
+ // As per Informal propositions 2: The Directrix shall lie on the ReferenceSurface.
+ // This is not always the case with the test files in the repository. I am not sure
+ // how to deal with this and whether my interpretation of the propositions is
+ // correct. However, if it has been asserted that the vertices of the directrix do
+ // not conform to the ReferenceSurface, the ReferenceSurface is ignored.
+ {
+ for (TopExp_Explorer exp(wire, TopAbs_VERTEX); exp.More(); exp.Next()) {
+ if (pln.Distance(BRep_Tool::Pnt(TopoDS::Vertex(exp.Current()))) > ALMOST_ZERO) {
+ directrix_on_plane = false;
+ Logger::Message(Logger::LOG_WARNING, "The Directrix does not lie on the ReferenceSurface", scs->instance);
+ break;
+ }
+ }
+ }
+ }
+
+ {
+ TopExp_Explorer exp(wire, TopAbs_EDGE);
+ TopoDS_Edge edge = TopoDS::Edge(exp.Current());
+ double u0, u1;
+ Handle(Geom_Curve) crv = BRep_Tool::Curve(edge, u0, u1);
+ crv->D1(u0, directrix_origin, directrix_tangent);
+ }
+
+ if (is_plane && pln.Axis().Direction().IsNormal(directrix_tangent, 1.e-5) && directrix_on_plane) {
+ directrix.SetTransformation(gp_Ax3(directrix_origin, directrix_tangent, pln.Axis().Direction()), gp::XOY());
+ } else if (!is_plane && surface) {
+ ShapeAnalysis_Surface sas(surface);
+ auto pnt2d = sas.ValueOfUV(directrix_origin, settings_.get().get());
+ // @todo should we revisit this pre 0.7 code wrt orientation?
+ /*
+ BRepGProp_Face prop(surface_face);
+ gp_Pnt _;
+ gp_Vec surface_normal;
+ prop.Normal(pnt2d.X(), pnt2d.Y(), _, surface_normal);
+ */
+ gp_Pnt _;
+ gp_Vec surface_normal_u, surface_normal_v;
+ surface->D1(pnt2d.X(), pnt2d.Y(), _, surface_normal_u, surface_normal_v);
+ // @todo check order
+ auto surface_normal = surface_normal_u.Crossed(surface_normal_v);
+ directrix.SetTransformation(gp_Ax3(directrix_origin, directrix_tangent, surface_normal), gp::XOY());
+ } else {
+ directrix.SetTransformation(gp_Ax3(directrix_origin, directrix_tangent), gp::XOY());
+ }
+ face = BRepBuilderAPI_Transform(face, directrix);
+
+ TopoDS_Face surface_face;
+ if (surface) {
+ surface_face = BRepBuilderAPI_MakeFace(surface, settings_.get().get()).Face();
+ }
+
+ if (!is_plane && surface) {
+ TopExp_Explorer exp(wire, TopAbs_EDGE);
+ for (; exp.More(); exp.Next()) {
+ ShapeFix_Edge sfe;
+ sfe.FixAddPCurve(TopoDS::Edge(exp.Current()), surface_face, false, settings_.get().get());
+ }
+ }
+
+ // NB: Note that StartParam and EndParam param are ignored and the assumption is
+ // made that the parametric range over which to be swept matches the IfcCurve in
+ // its entirety.
+ BRepOffsetAPI_MakePipeShell builder(wire);
+
+ {
+ TopExp_Explorer exp(face, TopAbs_WIRE);
+ section = TopoDS::Wire(exp.Current());
+ }
+
+ builder.Add(section);
+ builder.SetTransitionMode(BRepBuilderAPI_RightCorner);
+ if (directrix_on_plane) {
+ builder.SetMode(pln.Axis().Direction());
+ } else if (!is_plane) {
+ builder.SetMode(surface_face);
+ }
+ builder.Build();
+ builder.MakeSolid();
+ result = builder.Shape();
+
+ return true;
+}
+
+bool OpenCascadeKernel::convert_impl(const taxonomy::sweep_along_curve::ptr scs, IfcGeom::ConversionResults& results) {
+ TopoDS_Shape shape;
+ if (!convert(scs, shape)) {
+ return false;
+ }
+ results.emplace_back(ConversionResult(
+ scs->instance->data().id(),
+ scs->matrix,
+ new OpenCascadeShape(shape),
+ scs->surface_style
+ ));
+ return true;
+}