layerset-first setting

src/ifcgeom/IfcGeom.h

@@ -108,6 +108,7 @@ private:
 	double ifc_planeangle_unit;
 	double modelling_precision;
 	double dimensionality;
+	double layerset_first;
 
 #ifndef NO_CACHE
 	Cache cache;
@@ -146,7 +147,7 @@ public:
 		setValue(GV_PLANEANGLE_UNIT,          other.getValue(GV_PLANEANGLE_UNIT));
 		setValue(GV_PRECISION,                other.getValue(GV_PRECISION));
 		setValue(GV_DIMENSIONALITY,           other.getValue(GV_DIMENSIONALITY));
-		setValue(GV_DEFLECTION_TOLERANCE,     other.getValue(GV_DEFLECTION_TOLERANCE));
+		setValue(GV_LAYERSET_FIRST,           other.getValue(GV_LAYERSET_FIRST));
 		return *this;
 	}
 
@@ -181,7 +182,8 @@ public:
 		// Default: 0.00001 (obtained from IfcGeometricRepresentationContext if available)
 		GV_PRECISION,
 		// Whether to process shapes of type Face or higher (1) Wire or lower (-1) or all (0)
-		GV_DIMENSIONALITY
+		GV_DIMENSIONALITY,
+		GV_LAYERSET_FIRST
 	};
 
 	bool convert_wire_to_face(const TopoDS_Wire& wire, TopoDS_Face& face);

src/ifcgeom/IfcGeomFunctions.cpp

@@ -1084,6 +1084,9 @@ void IfcGeom::Kernel::setValue(GeomValue var, double value) {
 	case GV_DIMENSIONALITY:
 		dimensionality = value;
 		break;
+	case GV_LAYERSET_FIRST:
+		layerset_first = value;
+		break;
 	default:
 		assert(!"never reach here");
 	}
@@ -1115,6 +1118,9 @@ double IfcGeom::Kernel::getValue(GeomValue var) const {
 	case GV_DIMENSIONALITY:
 		return dimensionality;
 		break;
+	case GV_LAYERSET_FIRST:
+		return layerset_first;
+		break;
 	}
 	assert(!"never reach here");
 	return 0;
@@ -1422,7 +1428,7 @@ const IfcSchema::IfcMaterial* IfcGeom::Kernel::get_single_material_association(c
 		// the first material (in accordance with other viewers) when layerset-slicing is disabled.
 		if (!single_material && associated_material->as<IfcSchema::IfcMaterialLayerSetUsage>()) {
 			IfcSchema::IfcMaterialLayerSet* layerset = associated_material->as<IfcSchema::IfcMaterialLayerSetUsage>()->ForLayerSet();
-			if (layerset->MaterialLayers()->size() >= 1) {
+			if (getValue(GV_LAYERSET_FIRST) > 0.0 ? layerset->MaterialLayers()->size() >= 1 : layerset->MaterialLayers()->size() == 1) {
 				IfcSchema::IfcMaterialLayer* layer = (*layerset->MaterialLayers()->begin());
 				if (layer->hasMaterial()) {
 					single_material = layer->Material();

src/ifcgeom/IfcGeomIterator.h

@@ -712,6 +712,12 @@ namespace IfcGeom {
             kernel.setValue(IfcGeom::Kernel::GV_MAX_FACES_TO_SEW, settings.get(IteratorSettings::SEW_SHELLS) ? 1000 : -1);
             kernel.setValue(IfcGeom::Kernel::GV_DIMENSIONALITY, (settings.get(IteratorSettings::INCLUDE_CURVES)
                 ? (settings.get(IteratorSettings::EXCLUDE_SOLIDS_AND_SURFACES) ? -1. : 0.) : +1.));
+			kernel.setValue(IfcGeom::Kernel::GV_LAYERSET_FIRST,
+				settings.get(IteratorSettings::LAYERSET_FIRST)
+				? +1.0
+				: -1.0
+			);
+
 			if (settings.get(IteratorSettings::BUILDING_LOCAL_PLACEMENT)) {
 				if (settings.get(IteratorSettings::SITE_LOCAL_PLACEMENT)) {
 					Logger::Message(Logger::LOG_WARNING, "building-local-placement takes precedence over site-local-placement");

src/ifcgeom/IfcGeomIteratorSettings.h

@@ -84,8 +84,10 @@ namespace IfcGeom
 			SITE_LOCAL_PLACEMENT = 1 << 15,
 			///
 			BUILDING_LOCAL_PLACEMENT = 1 << 16,
+			/// Assigns the first layer material to the entire product
+			LAYERSET_FIRST = 1 << 17,
 			/// Number of different setting flags.
-			NUM_SETTINGS = 16
+			NUM_SETTINGS = 17
         };
         /// Used to store logical OR combination of setting flags.
         typedef unsigned SettingField;