Make sure compound structure is retained as SvgSerializer depends on it

src/ifcgeom/ConversionResult.h

@@ -282,6 +282,7 @@ namespace IfcGeom {
 		virtual ConversionResultShape* halfspaces() = 0;
 		virtual ConversionResultShape* box() = 0;
 		virtual ConversionResultShape* solid() = 0;
+		virtual ConversionResultShape* wrap_in_compound() = 0;
 
 		virtual std::vector<ConversionResultShape*> vertices() = 0;
 		virtual std::vector<ConversionResultShape*> edges() = 0;

src/ifcgeom/IfcGeomRepresentation.cpp

@@ -68,7 +68,7 @@ IfcGeom::ConversionResultShape* IfcGeom::Representation::BRep::as_compound(bool
 			delete accum;
 			accum = n;
 		} else {
-			accum = s;
+			accum = s->wrap_in_compound();
 		}
 	}
 

src/ifcgeom/kernels/cgal/CgalConversionResult.cpp

@@ -610,6 +610,11 @@ ConversionResultShape * ifcopenshell::geometry::CgalShape::box()
 	throw std::runtime_error("Not implemented");
 }
 
+ConversionResultShape* ifcopenshell::geometry::CgalShape::wrap_in_compound()
+{
+	return new CgalShape(poly(), convex_tag_);
+}
+
 std::vector<ConversionResultShape*> ifcopenshell::geometry::CgalShape::vertices()
 {
 	// @todo this is ridiculous
@@ -1001,4 +1006,10 @@ void ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::map(const std::vec
 	shape_ = std::move(nw);
 }
 
+
+ConversionResultShape* ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::wrap_in_compound()
+{
+	throw std::runtime_error("Not implemented");
+}
+
 #endif

src/ifcgeom/kernels/cgal/CgalConversionResult.h

@@ -244,6 +244,7 @@ namespace ifcopenshell { namespace geometry {
 		virtual ConversionResultShape* halfspaces();
 		virtual ConversionResultShape* solid();
 		virtual ConversionResultShape* box();
+		virtual ConversionResultShape* wrap_in_compound();
 
 		virtual std::vector<ConversionResultShape*> vertices();
 		virtual std::vector<ConversionResultShape*> edges();
@@ -312,6 +313,7 @@ namespace ifcopenshell { namespace geometry {
 		virtual ConversionResultShape* halfspaces();
 		virtual ConversionResultShape* solid();
 		virtual ConversionResultShape* box();
+		virtual ConversionResultShape* wrap_in_compound();
 
 		virtual std::vector<ConversionResultShape*> vertices();
 		virtual std::vector<ConversionResultShape*> edges();

src/ifcgeom/kernels/opencascade/OpenCascadeConversionResult.cpp

@@ -484,6 +484,15 @@ ConversionResultShape * ifcopenshell::geometry::OpenCascadeShape::box()
 	throw std::runtime_error("Not implemented");
 }
 
+ConversionResultShape* ifcopenshell::geometry::OpenCascadeShape::wrap_in_compound()
+{
+	TopoDS_Compound compound;
+	BRep_Builder builder;
+	builder.MakeCompound(compound);
+	builder.Add(compound, shape_);
+	return new OpenCascadeShape(std::move(compound));
+}
+
 std::vector<ConversionResultShape*> ifcopenshell::geometry::OpenCascadeShape::vertices()
 {
 	TopTools_IndexedMapOfShape map;
@@ -556,7 +565,9 @@ ConversionResultShape* ifcopenshell::geometry::OpenCascadeShape::concat(Conversi
 	auto& left = shape_;
 	auto& right = ((ifcopenshell::geometry::OpenCascadeShape*)other)->shape_;
 
-	if (left.ShapeType() == TopAbs_COMPOUND) {
+	// This reads a bit strange, but we want to specifically avoid compounds of faces that are
+	// the result of shell instances that are not sewn into a shell (yet).
+	if (left.ShapeType() == TopAbs_COMPOUND && !IfcGeom::util::is_compound_of_faces(left)) {
 		compound = TopoDS::Compound(left);
 	} else {
 		builder.MakeCompound(compound);

src/ifcgeom/kernels/opencascade/OpenCascadeConversionResult.h

@@ -90,6 +90,7 @@ namespace ifcopenshell {
 			virtual ConversionResultShape* halfspaces();
 			virtual ConversionResultShape* solid();
 			virtual ConversionResultShape* box();
+			virtual ConversionResultShape* wrap_in_compound();
 
 			virtual std::vector<ConversionResultShape*> vertices();
 			virtual std::vector<ConversionResultShape*> edges();

src/ifcgeom/kernels/opencascade/base_utils.cpp

@@ -607,7 +607,7 @@ gp_Pnt IfcGeom::util::point_above_plane(const gp_Pln& pln, bool agree) {
 	}
 }
 
-bool IfcGeom::util::is_compound(const TopoDS_Shape& shape) {
+bool IfcGeom::util::is_compound_of_faces(const TopoDS_Shape& shape) {
 	bool has_solids = TopExp_Explorer(shape, TopAbs_SOLID).More() != 0;
 	bool has_shells = TopExp_Explorer(shape, TopAbs_SHELL).More() != 0;
 	bool has_compounds = TopExp_Explorer(shape, TopAbs_COMPOUND).More() != 0;

src/ifcgeom/kernels/opencascade/base_utils.h

@@ -51,7 +51,7 @@ namespace IfcGeom {
 		IFC_GEOMLIBRARY_API bool create_solid_from_compound(const TopoDS_Shape& compound, TopoDS_Shape& solid, double tol);
 		IFC_GEOMLIBRARY_API bool shape_to_face_list(const TopoDS_Shape& s, TopTools_ListOfShape& li);
 		IFC_GEOMLIBRARY_API bool create_solid_from_faces(const TopTools_ListOfShape& face_list, TopoDS_Shape& solid, double tol, bool force_sewing = false);
-		IFC_GEOMLIBRARY_API bool is_compound(const TopoDS_Shape& shape);
+		IFC_GEOMLIBRARY_API bool is_compound_of_faces(const TopoDS_Shape& shape);
 		IFC_GEOMLIBRARY_API bool is_convex(const TopoDS_Wire& wire, double tol);
 		IFC_GEOMLIBRARY_API TopoDS_Shape halfspace_from_plane(const gp_Pln& pln, const gp_Pnt& cent);
 		IFC_GEOMLIBRARY_API gp_Pln plane_from_face(const TopoDS_Face& face);

src/ifcgeom/kernels/opencascade/boolean_utils.cpp

@@ -1431,7 +1431,7 @@ bool IfcGeom::util::boolean_operation(const boolean_settings& settings, const To
 }
 
 TopoDS_Shape IfcGeom::util::ensure_fit_for_subtraction(const TopoDS_Shape& shape, double tol) {
-	const bool is_comp = is_compound(shape);
+	const bool is_comp = is_compound_of_faces(shape);
 	if (!is_comp) {
 		return shape;
 	}

src/ifcwrap/IfcGeomWrapper.i

@@ -81,6 +81,7 @@
 %newobject IfcGeom::ConversionResultShape::intersect;
 %newobject IfcGeom::ConversionResultShape::concat;
 %newobject IfcGeom::ConversionResultShape::moved;
+%newobject IfcGeom::ConversionResultShape::wrap_in_compound;
 
 %newobject IfcGeom::ConversionResultShape::area;
 %newobject IfcGeom::ConversionResultShape::volume;