Honour IfcAxis2PlacementLinear Axis/RefDirection in the loft builder (#9408)

* Honour IfcAxis2PlacementLinear Axis/RefDirection in the loft builder

make_loft() (src/ifcgeom/infra_sweep_helper.cpp), shared by
IfcSectionedSolidHorizontal and IfcSectionedSurface, mishandled a cross
section's IfcAxis2PlacementLinear in two ways:

1. A placement carrying Axis but no RefDirection was placed with a fixed
   [e_y | e_z | e_x] world-axis permutation that ignored the directrix.
   On any directrix not running along +X (e.g. a north-south road
   pavement, or anywhere along a curve) the profile came out mis-oriented
   or collapsed to a sliver.

2. When two adjacent CrossSectionPositions used direction vectors
   inconsistently (a raked RefDirection at one, a plain Axis at the
   other) make_loft() logged GEO 42, dropped the rotation for the whole
   segment and squared every cap -- and in one configuration left the
   sweep frame flipped, so OpenCASCADE failed to build the solid at all.

Now a small profile_basis() helper builds every cross section's frame the
same way: profile Y = Axis, profile normal = RefDirection, and -- when
RefDirection is absent -- profile normal = the directrix tangent, so the
section stays perpendicular to the path (buildingSMART IFC4.x-IF #147).

When the two bracketing placements ask for the same orientation the sweep
frame carries it, built against the curve. When they disagree the sweep
frame stays on the shared Axis (continuous with the neighbouring
consistent segments, so nothing flips) and each end's own authored
orientation is folded into its profile points via a change of basis, so
each end cap still lands exactly as authored while the body in between
keeps following the directrix. The all-equal and no-direction-vector
paths are unchanged.

The two mappings now also carry the raw RefDirection through on
cross_section, alongside the existing rotation matrix.

Adds C++ tests (a raked end logs no GEO 42; a directrix that does not run
along +X still lofts a full-size solid) and Python tests (uniform prism
raked at one end and square at the other; a north-south directrix keeps
its width; OffsetLateral/OffsetVertical are scaled by the model length
unit).

* Renames profile_rotations to profile_axis for consistency with profile_ref_directions

src/ifcgeom/infra_sweep_helper.cpp

@@ -2,7 +2,9 @@
 #include "infra_sweep_helper.h"
 #include "function_item_evaluator.h"
 
+#include <algorithm>
 #include <boost/range/combine.hpp>
+#include <cassert>
 
 using namespace ifcopenshell::geom;
 
@@ -72,6 +74,53 @@ taxonomy::loft::ptr ifcopenshell::geom::make_loft(const ifcopenshell::geom::sett
 			longitudes.push_back(x.dist_along);
 		}
 		longitudes.push_back(std::numeric_limits<double>::infinity());
+
+		// Directrix frame (col0 = tangent, col1 = lateral, col2 = up, col3 = position) at
+		// every cross section station. Only needed to reconcile a cross section's own
+		// Axis / RefDirection against the curve; skip the work when no placement has one.
+		std::vector<Eigen::Matrix4d> section_directrix_frames;
+		if (std::any_of(cross_sections.begin(), cross_sections.end(),
+				[](const cross_section& cs) { return cs.rotation.has_value(); })) {
+			section_directrix_frames.reserve(cross_sections.size());
+			for (const auto& cs : cross_sections) {
+				section_directrix_frames.push_back(evaluator.evaluate(std::min(std::max(cs.dist_along, start), end)));
+			}
+		}
+
+		// The frame a cross section is placed in, given the directrix frame at its station
+		// and its own IfcAxis2PlacementLinear: profile X, profile Y = Axis, profile normal
+		// = RefDirection -- or, when RefDirection was not authored, the curve tangent, so
+		// the section stays perpendicular to the path (buildingSMART IFC4.x-IF #147). When
+		// the placement carries no direction vectors the section just follows the curve
+		// (lateral, up, tangent).
+		const auto profile_basis =
+			[](const std::optional<Eigen::Matrix3d>& rotation,
+			   const std::optional<Eigen::Vector3d>& ref_direction,
+			   const Eigen::Matrix4d& directrix_frame) -> Eigen::Matrix3d {
+			const Eigen::Vector3d tangent = directrix_frame.col(0).head<3>().normalized();
+			const Eigen::Vector3d lateral = directrix_frame.col(1).head<3>().normalized();
+			const Eigen::Vector3d up = directrix_frame.col(2).head<3>().normalized();
+			Eigen::Matrix3d B;
+			if (!rotation) {
+				B.col(0) = lateral;
+				B.col(1) = up;
+				B.col(2) = tangent;
+				return B;
+			}
+			const Eigen::Vector3d axis = rotation->col(2).normalized();
+			const Eigen::Vector3d normal = ref_direction ? ref_direction->normalized() : tangent;
+			Eigen::Vector3d x = axis.cross(normal);
+			if (x.norm() < 1.e-9) {
+				// Axis parallel to the normal: fall back to the curve's own lateral.
+				x = lateral - lateral.dot(axis) * axis;
+			}
+			x.normalize();
+			B.col(0) = x;
+			B.col(1) = axis;
+			B.col(2) = x.cross(axis);
+			return B;
+		};
+
 		auto profile_index = longitudes.begin();
 		for (size_t i = 0; i <= num_steps; ++i) {
             auto dist_along = start + delta_step * i;
@@ -88,6 +137,7 @@ taxonomy::loft::ptr ifcopenshell::geom::make_loft(const ifcopenshell::geom::sett
 			const auto& profile_a = cross_sections[std::distance(longitudes.begin(), profile_index)].section_geometry;
 			const auto& offset_a = cross_sections[std::distance(longitudes.begin(), profile_index)].offset;
 			const auto& rotation_a = cross_sections[std::distance(longitudes.begin(), profile_index)].rotation;
+			const auto& ref_direction_a = cross_sections[std::distance(longitudes.begin(), profile_index)].ref_direction;
 
 			taxonomy::geom_item::ptr interpolated = nullptr;
 
@@ -98,26 +148,37 @@ taxonomy::loft::ptr ifcopenshell::geom::make_loft(const ifcopenshell::geom::sett
 				(profile_index + 1 < longitudes.end()) &&
 				(relative_dist_along >= 1.e-9 || offset_a.cwiseAbs().maxCoeff() > 0. || rotation_a);
 
+			// When both bracketing placements ask for the same orientation, drive the sweep
+			// frame from it directly (relative to the curve). When they disagree, keep the
+			// sweep frame on the curve and fold each section's own orientation into its
+			// profile points via section_basis_a / section_basis_b so the ends still land
+			// exactly as authored without twisting the body between them.
 			std::optional<Eigen::Matrix3d> interpolated_rotation;
+			std::optional<Eigen::Vector3d> interpolated_ref_direction;
+			Eigen::Matrix3d section_basis_a = Eigen::Matrix3d::Identity();
+			Eigen::Matrix3d section_basis_b = Eigen::Matrix3d::Identity();
 
 			if (should_interpolate) {
 				taxonomy::geom_item::ptr profile_b;
 				Eigen::Vector3d offset_b;
 				std::optional<Eigen::Matrix3d> rotation_b;
+				std::optional<Eigen::Vector3d> ref_direction_b;
 				if ((profile_index + 1 < longitudes.end())) {
 					profile_b = cross_sections[std::distance(longitudes.begin(), profile_index) + 1].section_geometry;
 					offset_b = cross_sections[std::distance(longitudes.begin(), profile_index) + 1].offset;
 					rotation_b = cross_sections[std::distance(longitudes.begin(), profile_index) + 1].rotation;
+					ref_direction_b = cross_sections[std::distance(longitudes.begin(), profile_index) + 1].ref_direction;
 				} else {
 					profile_b = profile_a;
 					offset_b = offset_a;
 					rotation_b = rotation_a;
+					ref_direction_b = ref_direction_a;
 				}
 
 				// Only interpolate if the profiles are different or either of the offsets is non-zero
 				bool should_interpolate2 =
 					(profile_a->instance != profile_b->instance) ||
-					(offset_a.cwiseAbs().maxCoeff() > 0. || offset_b.cwiseAbs().maxCoeff() > 0. || rotation_b);
+					(offset_a.cwiseAbs().maxCoeff() > 0. || offset_b.cwiseAbs().maxCoeff() > 0. || rotation_a || rotation_b);
 
 				if (should_interpolate2) {
 
@@ -160,12 +221,33 @@ taxonomy::loft::ptr ifcopenshell::geom::make_loft(const ifcopenshell::geom::sett
 					}
 
 					auto interpolated_offset = lerp(offset_a, offset_b, relative_dist_along);
-                    if (rotation_a == rotation_b && rotation_a) {
-                        // @todo we don't support an overridden rotation on only one of the placements
-                        // in which case we would need to lerp with the rotation component below in m4b.
-                        interpolated_rotation = lerp(*rotation_a, *rotation_b, relative_dist_along);
-                    } else if (rotation_a != rotation_b) {
-                        logger.error("GEO", 42, "Direction vectors on cross section placements only supported when used consistently");
+					if (rotation_a == rotation_b) {
+						// Same orientation on both placements (including both absent): the
+						// sweep frame carries it, built against the curve just below.
+						interpolated_rotation = rotation_a;
+						interpolated_ref_direction = ref_direction_a;
+					} else if (rotation_a || rotation_b) {
+						// The two placements disagree -- in practice they share an Axis but
+						// only one carries a RefDirection (a raked end against a square run).
+						// Drive the sweep frame from the shared Axis with the profile normal
+						// on the curve tangent -- identical to the neighbouring consistent
+						// segments, so m4b stays continuous across the boundary and the body
+						// never flips -- then fold each section's *own* authored orientation
+						// into its profile points through section_basis_a / section_basis_b,
+						// so each end cap still lands exactly as authored.
+						const auto ia = static_cast<std::size_t>(std::distance(longitudes.begin(), profile_index));
+						assert(ia + 1 < section_directrix_frames.size());
+						const std::optional<Eigen::Vector3d> no_ref;
+						const auto base_a = profile_basis(rotation_a, no_ref, section_directrix_frames[ia]);
+						const auto base_b = profile_basis(rotation_b, no_ref, section_directrix_frames[ia + 1]);
+						section_basis_a =
+							base_a.transpose() *
+							profile_basis(rotation_a, ref_direction_a, section_directrix_frames[ia]);
+						section_basis_b =
+							base_b.transpose() *
+							profile_basis(rotation_b, ref_direction_b, section_directrix_frames[ia + 1]);
+						interpolated_rotation = rotation_a ? rotation_a : rotation_b;
+						interpolated_ref_direction = no_ref;
 					}
 
 					taxonomy::loop::ptr w1, w2;
@@ -337,7 +419,9 @@ taxonomy::loft::ptr ifcopenshell::geom::make_loft(const ifcopenshell::geom::sett
                                 const auto& tagged_point_on_w1 = tag_to_point_on_w1[t];
                                 const auto& tagged_point_on_w2 = tag_to_point_on_w2[t];
 
-                                auto p3 = (lerp(tagged_point_on_w1->ccomponents(), tagged_point_on_w2->ccomponents(), relative_dist_along) + interpolated_offset).eval();
+                                const Eigen::Vector3d rebased_w1 = section_basis_a * tagged_point_on_w1->ccomponents();
+                                const Eigen::Vector3d rebased_w2 = section_basis_b * tagged_point_on_w2->ccomponents();
+                                auto p3 = (lerp(rebased_w1, rebased_w2, relative_dist_along) + interpolated_offset).eval();
 
                                 std::set<std::string> tags_for_this_point_on_subsequent_profile = {t};
 
@@ -357,7 +441,9 @@ taxonomy::loft::ptr ifcopenshell::geom::make_loft(const ifcopenshell::geom::sett
                         } else {
                             for (auto tmp__ : boost::combine(w1_points, w2_points)) {
                                 boost::tie(p1, p2) = tmp__;
-                                auto p3 = (lerp(p1->ccomponents(), p2->ccomponents(), relative_dist_along) + interpolated_offset).eval();
+                                const Eigen::Vector3d rebased_1 = section_basis_a * p1->ccomponents();
+                                const Eigen::Vector3d rebased_2 = section_basis_b * p2->ccomponents();
+                                auto p3 = (lerp(rebased_1, rebased_2, relative_dist_along) + interpolated_offset).eval();
                                 points.push_back(taxonomy::make<taxonomy::point3>(p3));
                             }
                         }
@@ -399,17 +485,13 @@ taxonomy::loft::ptr ifcopenshell::geom::make_loft(const ifcopenshell::geom::sett
 				std::wcout << "#" << pwf->instance.data().id() << " " << dist_along << ": " << m4.col(3).row(2).value() << std::endl;
 			}*/
 
+			// Sweep frame at this station: the profile orientation asked for by the
+			// (consistent) placements, built against the curve here so it follows the
+			// directrix. Falls back to the plain curve frame (lateral, up, tangent) when
+			// no placement carries direction vectors. Inconsistent placements keep this
+			// on the curve and are reconciled through section_basis_a / section_basis_b.
 			Eigen::Matrix4d m4b = Eigen::Matrix4d::Identity();
-			if (interpolated_rotation) {
-				// direction vectors on the linear placement overwrite the placement otherwise inferred from the tangent
-				m4b.col(0).head<3>() = interpolated_rotation->col(1);
-				m4b.col(1).head<3>() = interpolated_rotation->col(2);
-				m4b.col(2).head<3>() = interpolated_rotation->col(0);
-			} else {
-				m4b.col(0).head<3>() = m4.col(1).head<3>().normalized();
-				m4b.col(1).head<3>() = m4.col(2).head<3>().normalized();
-				m4b.col(2).head<3>() = m4.col(0).head<3>().normalized();
-			}
+			m4b.block<3, 3>(0, 0) = profile_basis(interpolated_rotation, interpolated_ref_direction, m4);
 			m4b.col(3).head<3>() = m4.col(3).head<3>();
 
 			if (interpolated) {

src/ifcgeom/infra_sweep_helper.h

@@ -14,7 +14,13 @@ namespace ifcopenshell {
 			double dist_along;
 			taxonomy::geom_item::ptr section_geometry;
 			Eigen::Vector3d offset;
+			// rotation: the IfcAxis2PlacementLinear basis [X | Y | Axis], or nullopt when
+			// the placement carries neither Axis nor RefDirection.
 			std::optional<Eigen::Matrix3d> rotation;
+			// ref_direction: the raw RefDirection, only when it was actually authored on the
+			// placement (rotation carries a default otherwise). When absent the profile
+			// normal comes from the directrix tangent -- see buildingSMART IFC4.x-IF #147.
+			std::optional<Eigen::Vector3d> ref_direction;
 
 			bool operator <(const cross_section& other) const {
 				return dist_along < other.dist_along;

src/ifcgeom/mapping/IfcSectionedSolidHorizontal.cpp

@@ -49,7 +49,8 @@ taxonomy::ptr mapping::map_impl(const IfcSchema::IfcSectionedSolidHorizontal& in
 	// The longitudes determine the range of the sweep and the offsets are interpolated in between
 	// sweep segments.
 	std::vector<Eigen::Vector3d> profile_offsets;
-	std::vector<std::optional<Eigen::Matrix3d>> profile_rotations;
+	std::vector<std::optional<Eigen::Matrix3d>> profile_axes;
+	std::vector<std::optional<Eigen::Vector3d>> profile_ref_directions;
 	std::vector<double> longitudes;
 
 	for (auto& cs : css) {
@@ -72,23 +73,27 @@ taxonomy::ptr mapping::map_impl(const IfcSchema::IfcSectionedSolidHorizontal& in
 		profile_offsets.push_back(po);
 
 		std::optional<Eigen::Matrix3d> rot;
+		std::optional<Eigen::Vector3d> ref_direction;
 		if (csp.Axis() && csp.RefDirection()) {
+			ref_direction = taxonomy::cast<taxonomy::direction3>(map(csp.RefDirection()))->ccomponents();
 			rot = taxonomy::matrix4(
 				Eigen::Vector3d(0, 0, 0),
 				taxonomy::cast<taxonomy::direction3>(map(csp.Axis()))->ccomponents(),
-				taxonomy::cast<taxonomy::direction3>(map(csp.RefDirection()))->ccomponents()).ccomponents().block<3,3>(0,0);
+				*ref_direction).ccomponents().block<3,3>(0,0);
 		} else if (csp.Axis()) {
 			rot = taxonomy::matrix4(
 				Eigen::Vector3d(0, 0, 0),
 				taxonomy::cast<taxonomy::direction3>(map(csp.Axis()))->ccomponents()).ccomponents().block<3, 3>(0, 0);
-        } else if (csp.RefDirection()) {
-            rot = taxonomy::matrix4(
-                Eigen::Vector3d(0, 0, 0),
-                Eigen::Vector3d(0, 0, 1),
-                taxonomy::cast<taxonomy::direction3>(map(csp.RefDirection()))->ccomponents()
+      } else if (csp.RefDirection()) {
+         ref_direction = taxonomy::cast<taxonomy::direction3>(map(csp.RefDirection()))->ccomponents();
+         rot = taxonomy::matrix4(
+               Eigen::Vector3d(0, 0, 0),
+               Eigen::Vector3d(0, 0, 1),
+               *ref_direction
 			).ccomponents().block<3, 3>(0, 0);
-        }
-		profile_rotations.push_back(rot);
+      }
+      profile_axes.push_back(rot);
+		profile_ref_directions.push_back(ref_direction);
 	}
 	if (faces.size() != profile_offsets.size()) {
 		logger_.warning("GEO", 286, "Expected CrossSections and CrossSectionPositions to be equal length, but got " + std::to_string(faces.size()) + " and " + std::to_string(profile_offsets.size()) + " respectively", inst);
@@ -100,7 +105,7 @@ taxonomy::ptr mapping::map_impl(const IfcSchema::IfcSectionedSolidHorizontal& in
 	}
 
 	for (size_t i = 0; i < faces.size(); ++i) {
-		cross_sections.push_back({ longitudes[i], faces[i], profile_offsets[i], profile_rotations[i]});
+        cross_sections.push_back({longitudes[i], faces[i], profile_offsets[i], profile_axes[i], profile_ref_directions[i]});
 	}
 #else
     return nullptr;

src/ifcgeom/mapping/IfcSectionedSurface.cpp

@@ -50,7 +50,8 @@ taxonomy::ptr mapping::map_impl(const IfcSchema::IfcSectionedSurface& inst) {
 	// The longitudes determine the range of the sweep and the offsets are interpolated in between
 	// sweep segments.
 	std::vector<Eigen::Vector3d> profile_offsets;
-	std::vector<std::optional<Eigen::Matrix3d>> profile_rotations;
+   std::vector<std::optional<Eigen::Matrix3d>> profile_axes;
+	std::vector<std::optional<Eigen::Vector3d>> profile_ref_directions;
 	std::vector<double> longitudes;
 
 	for (auto& cs : css) {
@@ -74,24 +75,28 @@ taxonomy::ptr mapping::map_impl(const IfcSchema::IfcSectionedSurface& inst) {
 		profile_offsets.push_back(po);
 
 		std::optional<Eigen::Matrix3d> rot;
+		std::optional<Eigen::Vector3d> ref_direction;
 		if (csp.Axis() && csp.RefDirection()) {
+			ref_direction = taxonomy::cast<taxonomy::direction3>(map(csp.RefDirection()))->ccomponents();
 			rot = taxonomy::matrix4(
 				Eigen::Vector3d(0, 0, 0),
 				taxonomy::cast<taxonomy::direction3>(map(csp.Axis()))->ccomponents(),
-				taxonomy::cast<taxonomy::direction3>(map(csp.RefDirection()))->ccomponents()).ccomponents().block<3, 3>(0, 0);
+				*ref_direction).ccomponents().block<3, 3>(0, 0);
 		} else if (csp.Axis()) {
 			rot = taxonomy::matrix4(
 				Eigen::Vector3d(0, 0, 0),
 				taxonomy::cast<taxonomy::direction3>(map(csp.Axis()))->ccomponents()).ccomponents().block<3, 3>(0, 0);
-        } else if (csp.RefDirection()) {
-            rot = taxonomy::matrix4(
-                      Eigen::Vector3d(0, 0, 0),
-                      Eigen::Vector3d(0, 0, 1),
-                      taxonomy::cast<taxonomy::direction3>(map(csp.RefDirection()))->ccomponents())
-                      .ccomponents()
-                      .block<3, 3>(0, 0);
-        }
-		profile_rotations.push_back(rot);
+      } else if (csp.RefDirection()) {
+         ref_direction = taxonomy::cast<taxonomy::direction3>(map(csp.RefDirection()))->ccomponents();
+         rot = taxonomy::matrix4(
+                     Eigen::Vector3d(0, 0, 0),
+                     Eigen::Vector3d(0, 0, 1),
+                     *ref_direction)
+                     .ccomponents()
+                     .block<3, 3>(0, 0);
+      }
+      profile_axes.push_back(rot);
+		profile_ref_directions.push_back(ref_direction);
 	}
 #else
 	return nullptr;
@@ -106,8 +111,8 @@ taxonomy::ptr mapping::map_impl(const IfcSchema::IfcSectionedSurface& inst) {
 	}
 
 	for (size_t i = 0; i < faces.size(); ++i) {
-		cross_sections.push_back({ longitudes[i], faces[i], profile_offsets[i], profile_rotations[i] });
-	}
+        cross_sections.push_back({longitudes[i], faces[i], profile_offsets[i], profile_axes[i], profile_ref_directions[i]});
+		}
 	}
 
 	return make_loft(settings_, inst, fn, cross_sections);

src/ifcgeom/tests/test_ifcopenshell_geometry.cpp

@@ -1,7 +1,9 @@
 #include <algorithm>
+#include <sstream>
 #include <string>
 #include <vector>
 
+#include <catch2/catch_approx.hpp>
 #include <catch2/catch_test_macros.hpp>
 
 #include "ifcgeom/converter.h"
@@ -148,8 +150,152 @@ const ifcopenshell::geom::geometry_conversion_task* task_for_product(
     return nullptr;
 }
 
+// A minimal IfcSectionedSolidHorizontal (IFC4X3_ADD2) whose two
+// IfcAxis2PlacementLinear cross section positions use direction vectors
+// inconsistently: the near position carries a raked RefDirection and a
+// 1/cos(theta) wider profile, the far position carries neither. Before the
+// make_loft() fix this logged GEO 42 and dropped the rotation, lofting a wedge.
+constexpr const char* RAKED_SECTIONED_SOLID_SPF = R"IFC(ISO-10303-21;
+HEADER;
+FILE_DESCRIPTION((''),'2;1');
+FILE_NAME('','',(''),(''),'','','');
+FILE_SCHEMA(('IFC4X3_ADD2'));
+ENDSEC;
+DATA;
+#1=IFCPROJECT('0RYK8PV8D0ee9DDm77xcTZ',$,'T',$,$,$,$,(#6),$);
+#2=IFCCARTESIANPOINT((0.,0.,0.));
+#3=IFCDIRECTION((0.,0.,1.));
+#4=IFCDIRECTION((1.,0.,0.));
+#5=IFCAXIS2PLACEMENT3D(#2,#3,#4);
+#6=IFCGEOMETRICREPRESENTATIONCONTEXT($,'Model',3,1.E-05,#5,$);
+#7=IFCGEOMETRICREPRESENTATIONSUBCONTEXT('Body','Model',*,*,*,*,#6,$,.MODEL_VIEW.,$);
+#8=IFCCARTESIANPOINT((0.,0.,0.));
+#9=IFCCARTESIANPOINT((40.,0.,0.));
+#10=IFCPOLYLINE((#8,#9));
+#11=IFCDIRECTION((0.,0.,1.));
+#12=IFCDIRECTION((0.9034641832977311,-0.42866358545853134,0.));
+#13=IFCPOINTBYDISTANCEEXPRESSION(IFCLENGTHMEASURE(0.),$,$,$,#10);
+#14=IFCAXIS2PLACEMENTLINEAR(#13,#11,#12);
+#15=IFCPOINTBYDISTANCEEXPRESSION(IFCLENGTHMEASURE(40.),$,$,$,#10);
+#16=IFCAXIS2PLACEMENTLINEAR(#15,#11,$);
+#17=IFCCARTESIANPOINTLIST2D(((-0.9223756168081689,0.),(0.9223756168081689,0.),(0.9223756168081689,6.),(-0.9223756168081689,6.),(-0.9223756168081689,0.)),$);
+#18=IFCINDEXEDPOLYCURVE(#17,$,.F.);
+#19=IFCARBITRARYCLOSEDPROFILEDEF(.AREA.,$,#18);
+#20=IFCCARTESIANPOINTLIST2D(((-0.8333333333333334,0.),(0.8333333333333334,0.),(0.8333333333333334,6.),(-0.8333333333333334,6.),(-0.8333333333333334,0.)),$);
+#21=IFCINDEXEDPOLYCURVE(#20,$,.F.);
+#22=IFCARBITRARYCLOSEDPROFILEDEF(.AREA.,$,#21);
+#23=IFCSECTIONEDSOLIDHORIZONTAL(#10,(#19,#22),(#14,#16));
+#24=IFCBUILDINGELEMENTPROXY('3cWcr4$892GAeKwryhDILR',$,'wingwall',$,$,$,#26,$,$);
+#25=IFCSHAPEREPRESENTATION(#7,'Body','AdvancedSweptSolid',(#23));
+#26=IFCPRODUCTDEFINITIONSHAPE($,$,(#25));
+ENDSEC;
+END-ISO-10303-21;
+)IFC";
+
+struct sectioned_solid_result {
+    std::size_t geo42_count = 0;
+    bool produced_brep = false;
+    double projected_area_x = 0.0;
+    double projected_area_y = 0.0;
+    double projected_area_z = 0.0;
+};
+
+sectioned_solid_result convert_sectioned_solid(const std::string& spf) {
+    std::istringstream stream(spf);
+    ifcopenshell::logger log;
+    log.output_format(ifcopenshell::logger::FMT_INMEMORY);
+    ifcopenshell::file file(stream, static_cast<int>(spf.size()), log);
+    REQUIRE(file.good());
+
+    ifcopenshell::geom::settings settings;
+    ifcopenshell::geom::converter converter(
+        ifcopenshell::geom::kernels::construct(&file, "opencascade", settings, log), &file, settings, log);
+
+    std::vector<ifcopenshell::geom::geometry_conversion_task> tasks;
+    std::vector<ifcopenshell::geom::filter_function> filters;
+    converter.mapping()->get_representations(tasks, filters);
+    REQUIRE(!tasks.empty());
+
+    sectioned_solid_result result;
+    for (const auto& task : tasks) {
+        REQUIRE(!task.products.empty());
+        auto* elem = converter.create_brep_for_representation_and_product(task.representation, task.products.front());
+        if (elem) {
+            result.produced_brep = true;
+            elem->calculate_projected_surface_area(
+                result.projected_area_x, result.projected_area_y, result.projected_area_z);
+        }
+        delete elem;
+    }
+    result.geo42_count = log.count("GEO42");
+    return result;
+}
+
+std::size_t count_geo42_converting(const std::string& spf) {
+    return convert_sectioned_solid(spf).geo42_count;
+}
+
+// A minimal IfcSectionedSolidHorizontal (IFC4X3_ADD2) whose cross section
+// placements carry an explicit Axis = (0,0,1) but no RefDirection, on a
+// directrix that runs along +Y (not the global +X). Per buildingSMART
+// IFC4.x-IF #147 the profile normal follows the directrix tangent, so the
+// 12 x 0.5 rectangle sweeps 60 along +Y: a plan (Z) projected area of ~720.
+// Before the fix the profile was placed with a fixed axis permutation that
+// ignored the directrix and the solid collapsed.
+constexpr const char* AXIS_ALIGNED_SECTIONED_SOLID_SPF = R"IFC(ISO-10303-21;
+HEADER;
+FILE_DESCRIPTION((''),'2;1');
+FILE_NAME('','',(''),(''),'','','');
+FILE_SCHEMA(('IFC4X3_ADD2'));
+ENDSEC;
+DATA;
+#1=IFCPROJECT('0RYK8PV8D0ee9DDm77xcTZ',$,'T',$,$,$,$,(#6),$);
+#2=IFCCARTESIANPOINT((0.,0.,0.));
+#3=IFCDIRECTION((0.,0.,1.));
+#4=IFCDIRECTION((1.,0.,0.));
+#5=IFCAXIS2PLACEMENT3D(#2,#3,#4);
+#6=IFCGEOMETRICREPRESENTATIONCONTEXT($,'Model',3,1.E-05,#5,$);
+#7=IFCGEOMETRICREPRESENTATIONSUBCONTEXT('Body','Model',*,*,*,*,#6,$,.MODEL_VIEW.,$);
+#8=IFCCARTESIANPOINT((0.,0.,0.));
+#9=IFCCARTESIANPOINT((0.,60.,0.));
+#10=IFCPOLYLINE((#8,#9));
+#11=IFCDIRECTION((0.,0.,1.));
+#13=IFCPOINTBYDISTANCEEXPRESSION(IFCLENGTHMEASURE(0.),$,$,$,#10);
+#14=IFCAXIS2PLACEMENTLINEAR(#13,#11,$);
+#15=IFCPOINTBYDISTANCEEXPRESSION(IFCLENGTHMEASURE(60.),$,$,$,#10);
+#16=IFCAXIS2PLACEMENTLINEAR(#15,#11,$);
+#17=IFCCARTESIANPOINTLIST2D(((-6.,0.),(6.,0.),(6.,0.5),(-6.,0.5),(-6.,0.)),$);
+#18=IFCINDEXEDPOLYCURVE(#17,$,.F.);
+#19=IFCARBITRARYCLOSEDPROFILEDEF(.AREA.,$,#18);
+#23=IFCSECTIONEDSOLIDHORIZONTAL(#10,(#19,#19),(#14,#16));
+#24=IFCBUILDINGELEMENTPROXY('3cWcr4$892GAeKwryhDILR',$,'pavement',$,$,$,#26,$,$);
+#25=IFCSHAPEREPRESENTATION(#7,'Body','AdvancedSweptSolid',(#23));
+#26=IFCPRODUCTDEFINITIONSHAPE($,$,(#25));
+ENDSEC;
+END-ISO-10303-21;
+)IFC";
+
 } // namespace
 
+TEST_CASE("IfcSectionedSolidHorizontal raked end cut does not log GEO 42", "[ifcgeom][infra-sweep]") {
+    if (std::string(STRINGIFY(IfcSchema)) != "Ifc4x3_add2") {
+        SKIP("fixture is authored for IFC4X3_ADD2");
+    }
+    CHECK(count_geo42_converting(RAKED_SECTIONED_SOLID_SPF) == 0);
+}
+
+TEST_CASE("IfcSectionedSolidHorizontal follows a non-axis-aligned directrix", "[ifcgeom][infra-sweep]") {
+    if (std::string(STRINGIFY(IfcSchema)) != "Ifc4x3_add2") {
+        SKIP("fixture is authored for IFC4X3_ADD2");
+    }
+    const auto result = convert_sectioned_solid(AXIS_ALIGNED_SECTIONED_SOLID_SPF);
+    CHECK(result.geo42_count == 0);
+    REQUIRE(result.produced_brep);
+    // Plan projection is the top plus the bottom of the slab, 2 x width x length;
+    // a collapsed sweep (the pre-fix behaviour) is nowhere near this.
+    CHECK(result.projected_area_z == Catch::Approx(2.0 * 12.0 * 60.0).margin(2.0));
+}
+
 TEST_CASE("IfcGeom C++ fixture creates walls below and above the void limit", "[ifcgeom][voids]") {
     hierarchy_helper<IfcSchema> below_limit_file;
     const auto below_limit_wall = create_wall_with_voids(below_limit_file, MAX_VOIDS - 1);