SPE-2301: Add a new option that makes a printer print loops clockwise instead of counterclockwise.

src/libslic3r/Fill/Fill.cpp

@@ -508,13 +508,14 @@ void Layer::make_fills(FillAdaptive::Octree* adaptive_fill_octree, FillAdaptive:
 
         // apply half spacing using this flow's own spacing and generate infill
         FillParams params;
-        params.density           = float(0.01 * surface_fill.params.density);
-        params.dont_adjust       = false; //  surface_fill.params.dont_adjust;
-        params.anchor_length     = surface_fill.params.anchor_length;
-        params.anchor_length_max = surface_fill.params.anchor_length_max;
-        params.resolution        = resolution;
-        params.use_arachne       = (perimeter_generator == PerimeterGeneratorType::Arachne && surface_fill.params.pattern == ipConcentric) || surface_fill.params.pattern == ipEnsuring;
-        params.layer_height      = layerm.layer()->height;
+        params.density                    = float(0.01 * surface_fill.params.density);
+        params.dont_adjust                = false; //  surface_fill.params.dont_adjust;
+        params.anchor_length              = surface_fill.params.anchor_length;
+        params.anchor_length_max          = surface_fill.params.anchor_length_max;
+        params.resolution                 = resolution;
+        params.use_arachne                = (perimeter_generator == PerimeterGeneratorType::Arachne && surface_fill.params.pattern == ipConcentric) || surface_fill.params.pattern == ipEnsuring;
+        params.layer_height               = layerm.layer()->height;
+        params.prefer_clockwise_movements = this->object()->print()->config().prefer_clockwise_movements;
 
         for (ExPolygon &expoly : surface_fill.expolygons) {
 			// Spacing is modified by the filler to indicate adjustments. Reset it for each expolygon.
@@ -569,11 +570,12 @@ void Layer::make_fills(FillAdaptive::Octree* adaptive_fill_octree, FillAdaptive:
 
                     thick_polylines.clear();
                 } else {
+                    // When prefer_clockwise_movements is true, we have to ensure that extrusion paths will not be reversed during path planning.
                     extrusion_entities_append_paths(
                         eec->entities, std::move(polylines),
 						ExtrusionAttributes{ surface_fill.params.extrusion_role,
 							ExtrusionFlow{ flow_mm3_per_mm, float(flow_width), surface_fill.params.flow.height() } 
-						});
+						}, !params.prefer_clockwise_movements);
                     layerm.m_fills.entities.push_back(eec);
                 }
                 insert_fills_into_islands(*this, uint32_t(surface_fill.region_id), fill_begin, uint32_t(layerm.fills().size()));

src/libslic3r/Fill/FillBase.hpp

@@ -72,6 +72,9 @@ struct FillParams
     bool        use_arachne     { false };
     // Layer height for Concentric infill with Arachne.
     coordf_t    layer_height    { 0.f };
+
+    // For infills that produce closed loops to force printing those loops clockwise.
+    bool        prefer_clockwise_movements { false };
 };
 static_assert(IsTriviallyCopyable<FillParams>::value, "FillParams class is not POD (and it should be - see constructor).");
 

src/libslic3r/Fill/FillConcentric.cpp

@@ -56,14 +56,19 @@ void FillConcentric::_fill_surface_single(
     // clip the paths to prevent the extruder from getting exactly on the first point of the loop
     // Keep valid paths only.
     size_t j = iPathFirst;
-    for (size_t i = iPathFirst; i < polylines_out.size(); ++ i) {
+    for (size_t i = iPathFirst; i < polylines_out.size(); ++i) {
         polylines_out[i].clip_end(this->loop_clipping);
         if (polylines_out[i].is_valid()) {
+            if (params.prefer_clockwise_movements)
+                polylines_out[i].reverse();
+
             if (j < i)
                 polylines_out[j] = std::move(polylines_out[i]);
-            ++ j;
+
+            ++j;
         }
     }
+
     if (j < polylines_out.size())
         polylines_out.erase(polylines_out.begin() + int(j), polylines_out.end());
     //TODO: return ExtrusionLoop objects to get better chained paths,
@@ -94,6 +99,7 @@ void FillConcentric::_fill_surface_single(const FillParams              &params,
         for (Arachne::VariableWidthLines &loop : loops) {
             if (loop.empty())
                 continue;
+
             for (const Arachne::ExtrusionLine &wall : loop)
                 all_extrusions.emplace_back(&wall);
         }
@@ -106,8 +112,14 @@ void FillConcentric::_fill_surface_single(const FillParams              &params,
                 continue;
 
             ThickPolyline thick_polyline = Arachne::to_thick_polyline(*extrusion);
-            if (extrusion->is_closed)
+            if (extrusion->is_closed) {
+                // Arachne produces contour with clockwise orientation and holes with counterclockwise orientation.
+                if (const bool extrusion_reverse = params.prefer_clockwise_movements ? !extrusion->is_contour() : extrusion->is_contour(); extrusion_reverse)
+                    thick_polyline.reverse();
+
                 thick_polyline.start_at_index(nearest_point_index(thick_polyline.points, last_pos));
+            }
+
             thick_polylines_out.emplace_back(std::move(thick_polyline));
             last_pos = thick_polylines_out.back().last_point();
         }

src/libslic3r/Fill/FillEnsuring.cpp

@@ -308,19 +308,25 @@ ThickPolylines make_fill_polylines(
                 for (Arachne::VariableWidthLines &loop : loops) {
                     if (loop.empty())
                         continue;
+
                     for (const Arachne::ExtrusionLine &wall : loop)
                         all_extrusions.emplace_back(&wall);
                 }
 
                 for (const Arachne::ExtrusionLine *extrusion : all_extrusions) {
-                    if (extrusion->junctions.size() < 2) {
+                    if (extrusion->junctions.size() < 2)
                         continue;
-                    }
+
                     ThickPolyline thick_polyline = Arachne::to_thick_polyline(*extrusion);
                     if (extrusion->is_closed) {
+                        // Arachne produces contour with clockwise orientation and holes with counterclockwise orientation.
+                        if (const bool extrusion_reverse = params.prefer_clockwise_movements ? !extrusion->is_contour() : extrusion->is_contour(); extrusion_reverse)
+                            thick_polyline.reverse();
+
                         thick_polyline.start_at_index(nearest_point_index(thick_polyline.points, ex_bb.min));
                         thick_polyline.clip_end(scaled_spacing * 0.5);
                     }
+
                     if (thick_polyline.is_valid() && thick_polyline.length() > 0 && thick_polyline.points.size() > 1) {
                         thick_polylines.push_back(thick_polyline);
                     }

src/libslic3r/GCode.cpp

@@ -2977,8 +2977,10 @@ static constexpr const double min_gcode_segment_length = 0.002;
 
 std::string GCodeGenerator::extrude_loop(const ExtrusionLoop &loop_src, const GCode::SmoothPathCache &smooth_path_cache, const std::string_view description, double speed)
 {
-    // Extrude all loops CCW.
-    bool is_hole = loop_src.is_clockwise();
+    // Extrude all loops CCW unless CW movements are prefered.
+    const bool is_hole      = loop_src.is_clockwise();
+    const bool reverse_loop = m_config.prefer_clockwise_movements ? !is_hole : is_hole;
+
     Point seam_point = this->last_position.has_value() ? *this->last_position : Point::Zero();
     if (!m_config.spiral_vase && comment_is_perimeter(description)) {
         assert(m_layer != nullptr);
@@ -2986,8 +2988,7 @@ std::string GCodeGenerator::extrude_loop(const ExtrusionLoop &loop_src, const GC
     }
     // Because the G-code export has 1um resolution, don't generate segments shorter than 1.5 microns,
     // thus empty path segments will not be produced by G-code export.
-    GCode::SmoothPath smooth_path = smooth_path_cache.resolve_or_fit_split_with_seam(
-        loop_src, is_hole, m_scaled_resolution, seam_point, scaled<double>(0.0015));
+    GCode::SmoothPath smooth_path = smooth_path_cache.resolve_or_fit_split_with_seam(loop_src, reverse_loop, m_scaled_resolution, seam_point, scaled<double>(0.0015));
 
     // Clip the path to avoid the extruder to get exactly on the first point of the loop;
     // if polyline was shorter than the clipping distance we'd get a null polyline, so
@@ -3018,7 +3019,7 @@ std::string GCodeGenerator::extrude_loop(const ExtrusionLoop &loop_src, const GC
     } else if (loop_src.paths.back().role().is_external_perimeter() && m_layer != nullptr && m_config.perimeters.value > 1) {
         // Only wipe inside if the wipe along the perimeter is disabled.
         // Make a little move inwards before leaving loop.
-        if (std::optional<Point> pt = wipe_hide_seam(smooth_path, is_hole, scale_(EXTRUDER_CONFIG(nozzle_diameter))); pt) {
+        if (std::optional<Point> pt = wipe_hide_seam(smooth_path, reverse_loop, scale_(EXTRUDER_CONFIG(nozzle_diameter))); pt) {
             // Generate the seam hiding travel move.
             gcode += m_writer.travel_to_xy(this->point_to_gcode(*pt), "move inwards before travel");
             this->last_position = *pt;
@@ -3033,9 +3034,10 @@ std::string GCodeGenerator::extrude_skirt(
     const GCode::SmoothPathCache &smooth_path_cache, const std::string_view description, double speed)
 {
     assert(loop_src.is_counter_clockwise());
+    const bool reverse_loop = m_config.prefer_clockwise_movements;
+
     Point seam_point = this->last_position.has_value() ? *this->last_position : Point::Zero();
-    GCode::SmoothPath smooth_path = smooth_path_cache.resolve_or_fit_split_with_seam(
-        loop_src, false, m_scaled_resolution, seam_point, scaled<double>(0.0015));
+    GCode::SmoothPath smooth_path = smooth_path_cache.resolve_or_fit_split_with_seam(loop_src, reverse_loop, m_scaled_resolution, seam_point, scaled<double>(0.0015));
 
     // Clip the path to avoid the extruder to get exactly on the first point of the loop;
     // if polyline was shorter than the clipping distance we'd get a null polyline, so

src/libslic3r/GCode/Wipe.cpp

@@ -187,7 +187,7 @@ std::string Wipe::wipe(GCodeGenerator &gcodegen, bool toolchange)
 // Make a little move inwards before leaving loop after path was extruded,
 // thus the current extruder position is at the end of a path and the path
 // may not be closed in case the loop was clipped to hide a seam.
-std::optional<Point> wipe_hide_seam(const SmoothPath &path, bool is_hole, double wipe_length)
+std::optional<Point> wipe_hide_seam(const SmoothPath &path, const bool path_reversed, const double wipe_length)
 {
     assert(! path.empty());
     assert(path.front().path.size() >= 2);
@@ -222,7 +222,7 @@ std::optional<Point> wipe_hide_seam(const SmoothPath &path, bool is_hole, double
         double angle_inside = angle(p_next - p_current, p_prev - p_current);
         assert(angle_inside >= -M_PI && angle_inside <= M_PI);
         // 3rd of this angle will be taken, thus make the angle monotonic before interpolation.
-        if (is_hole) {
+        if (path_reversed) {
             if (angle_inside > 0)
                 angle_inside -= 2.0 * M_PI;
         } else {

src/libslic3r/Preset.cpp

@@ -506,7 +506,7 @@ static std::vector<std::string> s_Preset_machine_limits_options {
 static std::vector<std::string> s_Preset_printer_options {
     "printer_technology", "autoemit_temperature_commands",
     "bed_shape", "bed_custom_texture", "bed_custom_model", "binary_gcode", "z_offset", "gcode_flavor", "use_relative_e_distances",
-    "use_firmware_retraction", "use_volumetric_e", "variable_layer_height",
+    "use_firmware_retraction", "use_volumetric_e", "variable_layer_height", "prefer_clockwise_movements",
     //FIXME the print host keys are left here just for conversion from the Printer preset to Physical Printer preset.
     "host_type", "print_host", "printhost_apikey", "printhost_cafile",
     "single_extruder_multi_material", "start_gcode", "end_gcode", "before_layer_gcode", "layer_gcode", "toolchange_gcode",

src/libslic3r/Print.cpp

@@ -211,7 +211,8 @@ bool Print::invalidate_state_by_config_options(const ConfigOptionResolver & /* n
             // Therefore toggling the Spiral Vase on / off requires complete reslicing.
             || opt_key == "spiral_vase"
             || opt_key == "filament_shrinkage_compensation_xy"
-            || opt_key == "filament_shrinkage_compensation_z") {
+            || opt_key == "filament_shrinkage_compensation_z"
+            || opt_key == "prefer_clockwise_movements") {
             osteps.emplace_back(posSlice);
         } else if (
                opt_key == "complete_objects"

src/libslic3r/PrintConfig.cpp

@@ -3366,6 +3366,13 @@ void PrintConfigDef::init_fff_params()
     def->mode = comExpert;
     def->set_default_value(new ConfigOptionBool(true));
 
+    def = this->add("prefer_clockwise_movements", coBool);
+    def->label = L("Prefer clockwise movements");
+    def->tooltip = L("This setting makes the printer print loops clockwise instead of counterclockwise. "
+                     "Most printers don't need to print loops clockwise.");
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionBool(false));
+
     def = this->add("wipe", coBools);
     def->label = L("Wipe while retracting");
     def->tooltip = L("This flag will move the nozzle while retracting to minimize the possible blob "

src/libslic3r/PrintConfig.hpp

@@ -864,6 +864,7 @@ PRINT_CONFIG_CLASS_DERIVED_DEFINE(
     ((ConfigOptionString,             output_filename_format))
     ((ConfigOptionFloat,              perimeter_acceleration))
     ((ConfigOptionStrings,            post_process))
+    ((ConfigOptionBool,               prefer_clockwise_movements))
     ((ConfigOptionString,             printer_model))
     ((ConfigOptionString,             printer_notes))
     ((ConfigOptionFloat,              resolution))

src/libslic3r/Support/SupportCommon.cpp

@@ -519,18 +519,19 @@ static inline void fill_expolygons_generate_paths(
     fill_expolygons_generate_paths(dst, std::move(expolygons), filler, fill_params, density, role, flow);
 }
 
-static Polylines draw_perimeters(const ExPolygon &expoly, double clip_length)
-{
+static Polylines draw_perimeters(const ExPolygon &expoly, double clip_length, const bool prefer_clockwise_movements) {
     // Draw the perimeters.
     Polylines polylines;
     polylines.reserve(expoly.holes.size() + 1);
     for (size_t i = 0; i <= expoly.holes.size();  ++ i) {
         Polyline pl(i == 0 ? expoly.contour.points : expoly.holes[i - 1].points);
         pl.points.emplace_back(pl.points.front());
-        if (i > 0)
-            // It is a hole, reverse it.
+
+        // When prefer_clockwise_movements is true ensure that all loops are CW oriented (reverse contour),
+        // otherwise ensure that all loops are CCW oriented (reverse loops).
+        if (const bool loop_reverse = prefer_clockwise_movements ? i == 0 : i > 0; loop_reverse)
             pl.reverse();
-        // so that all contours are CCW oriented.
+
         pl.clip_end(clip_length);
         polylines.emplace_back(std::move(pl));
     }
@@ -647,7 +648,7 @@ static inline void tree_supports_generate_paths(
                 ExPolygons level2 = offset2_ex({ expoly }, -1.5 * flow.scaled_width(), 0.5 * flow.scaled_width());
                 if (level2.size() == 1) {
                     Polylines polylines;
-                    extrusion_entities_append_paths(eec->entities, draw_perimeters(expoly, clip_length), { ExtrusionRole::SupportMaterial, flow },
+                    extrusion_entities_append_paths(eec->entities, draw_perimeters(expoly, clip_length, support_params.prefer_clockwise_movements), { ExtrusionRole::SupportMaterial, flow },
                         // Disable reversal of the path, always start with the anchor, always print CCW.
                         false);
                     expoly = level2.front();
@@ -659,10 +660,14 @@ static inline void tree_supports_generate_paths(
         // The anchor candidate points are annotated with an index of the source contour or with -1 if on intersection.
         anchor_candidates.clear();
         shrink_expolygon_with_contour_idx(expoly, flow.scaled_width(), DefaultJoinType, 1.2, anchor_candidates);
-        // Orient all contours CW.
-        for (auto &path : anchor_candidates)
-            if (ClipperLib_Z::Area(path) > 0)
+
+        // Based on the way how loops with anchors are constructed (we reverse orientation at the end),
+        // orient all loops CCW when prefer_clockwise_movements is true and orient all loops CW otherwise.
+        for (auto &path : anchor_candidates) {
+            const bool is_ccw = ClipperLib_Z::Area(path) > 0;
+            if (const bool path_reverse = support_params.prefer_clockwise_movements ? !is_ccw : is_ccw; path_reverse)
                 std::reverse(path.begin(), path.end());
+        }
 
         // Draw the perimeters.
         Polylines polylines;
@@ -671,10 +676,12 @@ static inline void tree_supports_generate_paths(
             // Open the loop with a seam.
             const Polygon &loop = expoly.contour_or_hole(idx_loop);
             Polyline pl(loop.points);
-            // Orient all contours CW, because the anchor will be added to the end of polyline while we want to start a loop with the anchor.
-            if (idx_loop == 0)
-                // It is an outer contour.
+
+            // When prefer_clockwise_movements is true, orient all loops CCW and orient all loops CW otherwise
+            // because the anchor will be added to the end of the polyline while we want to start a loop with the anchor.
+            if (const bool loop_reverse = support_params.prefer_clockwise_movements ? idx_loop != 0 : idx_loop == 0; loop_reverse)
                 pl.reverse();
+
             pl.points.emplace_back(pl.points.front());
             pl.clip_end(clip_length);
             if (pl.size() < 2)
@@ -767,11 +774,12 @@ static inline void fill_expolygons_with_sheath_generate_paths(
     ExtrusionEntitiesPtr    &dst,
     const Polygons          &polygons,
     Fill                    *filler,
-    float                    density,
-    ExtrusionRole            role,
+    const float              density,
+    const ExtrusionRole      role,
     const Flow              &flow,
-    bool                     with_sheath,
-    bool                     no_sort)
+    const bool               with_sheath,
+    const bool               no_sort,
+    const bool               prefer_clockwise_movements)
 {
     if (polygons.empty())
         return;
@@ -797,7 +805,7 @@ static inline void fill_expolygons_with_sheath_generate_paths(
             eec->no_sort = true;
         }
         ExtrusionEntitiesPtr &out = no_sort ? eec->entities : dst;
-        extrusion_entities_append_paths(out, draw_perimeters(expoly, clip_length), { ExtrusionRole::SupportMaterial, flow });
+        extrusion_entities_append_paths(out, draw_perimeters(expoly, clip_length, prefer_clockwise_movements), { ExtrusionRole::SupportMaterial, flow }, false);
         // Fill in the rest.
         fill_expolygons_generate_paths(out, offset_ex(expoly, float(-0.4 * spacing)), filler, fill_params, density, role, flow);
         if (no_sort && ! eec->empty())
@@ -1526,7 +1534,7 @@ void generate_support_toolpaths(
                         filler, float(support_params.support_density),
                         // Extrusion parameters
                         ExtrusionRole::SupportMaterial, flow,
-                        support_params.with_sheath, false);
+                        support_params.with_sheath, false, support_params.prefer_clockwise_movements);
                 }
                 if (! tree_polygons.empty())
                     tree_supports_generate_paths(support_layer.support_fills.entities, tree_polygons, flow, support_params);
@@ -1561,7 +1569,7 @@ void generate_support_toolpaths(
                 // Extrusion parameters
                 (support_layer_id < slicing_params.base_raft_layers) ? ExtrusionRole::SupportMaterial : ExtrusionRole::SupportMaterialInterface, flow, 
                 // sheath at first layer
-                support_layer_id == 0, support_layer_id == 0);
+                support_layer_id == 0, support_layer_id == 0, support_params.prefer_clockwise_movements);
         }
     });
 
@@ -1802,7 +1810,7 @@ void generate_support_toolpaths(
                         filler, density,
                         // Extrusion parameters
                         ExtrusionRole::SupportMaterial, flow,
-                        sheath, no_sort);
+                        sheath, no_sort, support_params.prefer_clockwise_movements);
             }
 
             // Merge base_interface_layers to base_layers to avoid unneccessary retractions

src/libslic3r/Support/SupportParameters.cpp

@@ -143,6 +143,8 @@ SupportParameters::SupportParameters(const PrintObject &object)
     }
 
     this->tree_branch_diameter_double_wall_area_scaled = 0.25 * sqr(scaled<double>(object_config.support_tree_branch_diameter_double_wall.value)) * M_PI;
+
+    this->prefer_clockwise_movements = print_config.prefer_clockwise_movements;
 }
 
 } // namespace Slic3r

src/libslic3r/Support/SupportParameters.hpp

@@ -88,6 +88,9 @@ struct SupportParameters {
     float 					raft_angle_base;
     float 					raft_angle_interface;
 
+    // Print closed loop clockwise when it is equal to true.
+    bool                    prefer_clockwise_movements;
+
     // Produce a raft interface angle for a given SupportLayer::interface_id()
     float 					raft_interface_angle(size_t interface_id) const 
     	{ return this->raft_angle_interface + ((interface_id & 1) ? float(- M_PI / 4.) : float(+ M_PI / 4.)); }

src/slic3r/GUI/Tab.cpp

@@ -2785,6 +2785,7 @@ void TabPrinter::build_fff()
         optgroup->append_single_option_line("use_firmware_retraction");
         optgroup->append_single_option_line("use_volumetric_e");
         optgroup->append_single_option_line("variable_layer_height");
+        optgroup->append_single_option_line("prefer_clockwise_movements");
 
     const int gcode_field_height = 15; // 150
     const int notes_field_height = 25; // 250