Add "2D Lattice" fill pattern for lightweight aircraft structures (#8293)

* Add 2D lattice infill pattern

* Add state invalidation behavior for lattice infill angles

* Update SurfaceFillParams methods to account for lattice infill angles

---------

Co-authored-by: SoftFever <softfeverever@gmail.com>
Co-authored-by: Noisyfox <timemanager.rick@gmail.com>

src/libslic3r/Fill/Fill.cpp

@@ -64,6 +64,10 @@ struct SurfaceFillParams
 	float			top_surface_speed = 0;
 	float			solid_infill_speed = 0;
 
+    // Params for lattice infill angles
+    float lattice_angle_1 = 0.f;
+    float lattice_angle_2 = 0.f;
+
 	bool operator<(const SurfaceFillParams &rhs) const {
 #define RETURN_COMPARE_NON_EQUAL(KEY) if (this->KEY < rhs.KEY) return true; if (this->KEY > rhs.KEY) return false;
 #define RETURN_COMPARE_NON_EQUAL_TYPED(TYPE, KEY) if (TYPE(this->KEY) < TYPE(rhs.KEY)) return true; if (TYPE(this->KEY) > TYPE(rhs.KEY)) return false;
@@ -90,6 +94,8 @@ struct SurfaceFillParams
 		RETURN_COMPARE_NON_EQUAL(sparse_infill_speed);
 		RETURN_COMPARE_NON_EQUAL(top_surface_speed);
 		RETURN_COMPARE_NON_EQUAL(solid_infill_speed);
+        RETURN_COMPARE_NON_EQUAL(lattice_angle_1);
+		RETURN_COMPARE_NON_EQUAL(lattice_angle_2);
 
 		return false;
 	}
@@ -111,7 +117,9 @@ struct SurfaceFillParams
 				this->extrusion_role	== rhs.extrusion_role	&&
 				this->sparse_infill_speed	== rhs.sparse_infill_speed &&
 				this->top_surface_speed		== rhs.top_surface_speed &&
-				this->solid_infill_speed	== rhs.solid_infill_speed;
+				this->solid_infill_speed	== rhs.solid_infill_speed &&
+                this->lattice_angle_1		== rhs.lattice_angle_1 &&
+				this->lattice_angle_2	    == rhs.lattice_angle_2;
 	}
 };
 
@@ -611,6 +619,8 @@ std::vector<SurfaceFill> group_fills(const Layer &layer)
 		        params.extruder 	 = layerm.region().extruder(extrusion_role);
 		        params.pattern 		 = region_config.sparse_infill_pattern.value;
 		        params.density       = float(region_config.sparse_infill_density);
+                params.lattice_angle_1 = region_config.lattice_angle_1;
+                params.lattice_angle_2 = region_config.lattice_angle_2;
 
 		        if (surface.is_solid()) {
 		            params.density = 100.f;
@@ -953,6 +963,8 @@ void Layer::make_fills(FillAdaptive::Octree* adaptive_fill_octree, FillAdaptive:
 		params.resolution        = resolution;
         params.use_arachne       = surface_fill.params.pattern == ipConcentric || surface_fill.params.pattern == ipConcentricInternal;
         params.layer_height      = layerm->layer()->height;
+        params.lattice_angle_1   = surface_fill.params.lattice_angle_1; 
+        params.lattice_angle_2   = surface_fill.params.lattice_angle_2;
 
 		// BBS
 		params.flow = surface_fill.params.flow;
@@ -1022,6 +1034,7 @@ Polylines Layer::generate_sparse_infill_polylines_for_anchoring(FillAdaptive::Oc
         case ipMonotonicLine:
         case ipAlignedRectilinear:
         case ipGrid:
+        case ip2DLattice:
         case ipTriangles:
         case ipStars:
         case ipCubic:
@@ -1076,6 +1089,8 @@ Polylines Layer::generate_sparse_infill_polylines_for_anchoring(FillAdaptive::Oc
         params.resolution        = resolution;
         params.use_arachne       = false;
         params.layer_height      = layerm.layer()->height;
+        params.lattice_angle_1   = surface_fill.params.lattice_angle_1; 
+        params.lattice_angle_2   = surface_fill.params.lattice_angle_2; 
 
         for (ExPolygon &expoly : surface_fill.expolygons) {
             // Spacing is modified by the filler to indicate adjustments. Reset it for each expolygon.

src/libslic3r/Fill/FillBase.cpp

@@ -47,6 +47,7 @@ Fill* Fill::new_from_type(const InfillPattern type)
     case ipMonotonic:           return new FillMonotonic();
     case ipLine:                return new FillLine();
     case ipGrid:                return new FillGrid();
+    case ip2DLattice:           return new Fill2DLattice();
     case ipTriangles:           return new FillTriangles();
     case ipStars:               return new FillStars();
     case ipCubic:               return new FillCubic();

src/libslic3r/Fill/FillBase.hpp

@@ -69,6 +69,10 @@ struct FillParams
     // Layer height for Concentric infill with Arachne.
     coordf_t    layer_height    { 0.f };
 
+    // For 2D lattice
+    coordf_t    lattice_angle_1    { 0.f };
+    coordf_t    lattice_angle_2    { 0.f };
+
     // BBS
     Flow            flow;
     ExtrusionRole   extrusion_role{ ExtrusionRole(0) };

src/libslic3r/Fill/FillRectilinear.cpp

@@ -3002,6 +3002,23 @@ Polylines FillGrid::fill_surface(const Surface *surface, const FillParams &param
     return polylines_out;
 }
 
+Polylines Fill2DLattice::fill_surface(const Surface *surface, const FillParams &params)
+{
+    Polylines polylines_out;
+    coordf_t dx1 = tan(Geometry::deg2rad(params.lattice_angle_1)) * z;
+    coordf_t dx2 = tan(Geometry::deg2rad(params.lattice_angle_2)) * z;
+    if (! this->fill_surface_by_multilines(
+            surface, params,
+            { { float(M_PI / 2.), float(dx1) }, { float(M_PI / 2.), float(dx2) } },
+            polylines_out))
+        BOOST_LOG_TRIVIAL(error) << "Fill2DLattice::fill_surface() failed to fill a region.";
+
+    if (this->layer_id % 2 == 1)
+        for (int i = 0; i < polylines_out.size(); i++)
+            std::reverse(polylines_out[i].begin(), polylines_out[i].end());
+    return polylines_out;
+}
+
 Polylines FillTriangles::fill_surface(const Surface *surface, const FillParams &params)
 {
     Polylines polylines_out;

src/libslic3r/Fill/FillRectilinear.hpp

@@ -71,6 +71,18 @@ protected:
     float _layer_angle(size_t idx) const override { return 0.f; }
 };
 
+class Fill2DLattice : public FillRectilinear
+{
+public:
+    Fill* clone() const override { return new Fill2DLattice(*this); }
+    ~Fill2DLattice() override = default;
+    Polylines fill_surface(const Surface *surface, const FillParams &params) override;
+
+protected:
+	// The grid fill will keep the angle constant between the layers, see the implementation of Slic3r::Fill.
+    float _layer_angle(size_t idx) const override { return 0.f; }
+};
+
 class FillTriangles : public FillRectilinear
 {
 public:

src/libslic3r/Layer.cpp

@@ -391,6 +391,7 @@ coordf_t Layer::get_sparse_infill_max_void_area()
                 max_void_area = std::max(max_void_area, spacing * spacing);
                 break;
             case ipGrid:
+            case ip2DLattice:
             case ipHoneycomb:
             case ipLightning:
                 max_void_area = std::max(max_void_area, 4.0 * spacing * spacing);

src/libslic3r/Preset.cpp

@@ -784,7 +784,7 @@ static std::vector<std::string> s_Preset_print_options {
     "layer_height", "initial_layer_print_height", "wall_loops", "alternate_extra_wall", "slice_closing_radius", "spiral_mode", "spiral_mode_smooth", "spiral_mode_max_xy_smoothing", "slicing_mode",
     "top_shell_layers", "top_shell_thickness", "bottom_shell_layers", "bottom_shell_thickness",
     "extra_perimeters_on_overhangs", "ensure_vertical_shell_thickness", "reduce_crossing_wall", "detect_thin_wall", "detect_overhang_wall", "overhang_reverse", "overhang_reverse_threshold","overhang_reverse_internal_only", "wall_direction",
-    "seam_position", "staggered_inner_seams", "wall_sequence", "is_infill_first", "sparse_infill_density", "sparse_infill_pattern", "top_surface_pattern", "bottom_surface_pattern",
+    "seam_position", "staggered_inner_seams", "wall_sequence", "is_infill_first", "sparse_infill_density", "sparse_infill_pattern", "lattice_angle_1", "lattice_angle_2", "top_surface_pattern", "bottom_surface_pattern",
     "infill_direction", "solid_infill_direction", "rotate_solid_infill_direction",  "counterbore_hole_bridging",
     "minimum_sparse_infill_area", "reduce_infill_retraction","internal_solid_infill_pattern","gap_fill_target",
     "ironing_type", "ironing_pattern", "ironing_flow", "ironing_speed", "ironing_spacing", "ironing_angle", "ironing_inset",

src/libslic3r/PrintConfig.cpp

@@ -136,6 +136,7 @@ static t_config_enum_values s_keys_map_InfillPattern {
     { "concentric",         ipConcentric },
     { "zig-zag",            ipRectilinear },
     { "grid",               ipGrid },
+    { "2dlattice",          ip2DLattice },
     { "line",               ipLine },
     { "cubic",              ipCubic },
     { "triangles",          ipTriangles },
@@ -2282,6 +2283,7 @@ void PrintConfigDef::init_fff_params()
     def->enum_values.push_back("concentric");
     def->enum_values.push_back("zig-zag");
     def->enum_values.push_back("grid");
+    def->enum_values.push_back("2dlattice");
     def->enum_values.push_back("line");
     def->enum_values.push_back("cubic");
     def->enum_values.push_back("triangles");
@@ -2301,6 +2303,7 @@ void PrintConfigDef::init_fff_params()
     def->enum_labels.push_back(L("Concentric"));
     def->enum_labels.push_back(L("Rectilinear"));
     def->enum_labels.push_back(L("Grid"));
+    def->enum_labels.push_back(L("2D Lattice"));
     def->enum_labels.push_back(L("Line"));
     def->enum_labels.push_back(L("Cubic"));
     def->enum_labels.push_back(L("Triangles"));
@@ -2319,6 +2322,26 @@ void PrintConfigDef::init_fff_params()
     def->enum_labels.push_back(L("Quarter Cubic"));
     def->set_default_value(new ConfigOptionEnum<InfillPattern>(ipCrossHatch));
 
+    def           = this->add("lattice_angle_1", coFloat);
+    def->label    = L("Lattice angle 1");
+    def->category = L("Strength");
+    def->tooltip  = L("The angle of the first set of 2D lattice elements in the Z direction. Zero is vertical.");
+    def->sidetext = L("°");
+    def->min      = -75;
+    def->max      = 75;
+    def->mode     = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(-45));
+
+    def           = this->add("lattice_angle_2", coFloat);
+    def->label    = L("Lattice angle 2");
+    def->category = L("Strength");
+    def->tooltip  = L("The angle of the second set of 2D lattice elements in the Z direction. Zero is vertical.");
+    def->sidetext = L("°");
+    def->min      = -75;
+    def->max      = 75;
+    def->mode     = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(45));
+
     auto def_infill_anchor_min = def = this->add("infill_anchor", coFloatOrPercent);
     def->label = L("Sparse infill anchor length");
     def->category = L("Strength");

src/libslic3r/PrintConfig.hpp

@@ -58,7 +58,7 @@ enum AuthorizationType {
 };
 
 enum InfillPattern : int {
-    ipConcentric, ipRectilinear, ipGrid, ipLine, ipCubic, ipTriangles, ipStars, ipGyroid, ipHoneycomb, ipAdaptiveCubic, ipMonotonic, ipMonotonicLine, ipAlignedRectilinear, ip3DHoneycomb,
+    ipConcentric, ipRectilinear, ipGrid, ip2DLattice, ipLine, ipCubic, ipTriangles, ipStars, ipGyroid, ipHoneycomb, ipAdaptiveCubic, ipMonotonic, ipMonotonicLine, ipAlignedRectilinear, ip3DHoneycomb,
     ipHilbertCurve, ipArchimedeanChords, ipOctagramSpiral, ipSupportCubic, ipSupportBase, ipConcentricInternal,
     ipLightning, ipCrossHatch, ipQuarterCubic,
     ipCount,
@@ -923,6 +923,8 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionBool,                 rotate_solid_infill_direction))
     ((ConfigOptionPercent,              sparse_infill_density))
     ((ConfigOptionEnum<InfillPattern>,  sparse_infill_pattern))
+    ((ConfigOptionFloat,                lattice_angle_1))
+    ((ConfigOptionFloat,                lattice_angle_2))
     ((ConfigOptionEnum<FuzzySkinType>,  fuzzy_skin))
     ((ConfigOptionFloat,                fuzzy_skin_thickness))
     ((ConfigOptionFloat,                fuzzy_skin_point_distance))

src/libslic3r/PrintObject.cpp

@@ -1092,7 +1092,9 @@ bool PrintObject::invalidate_state_by_config_options(
             || opt_key == "infill_anchor_max"
             || opt_key == "top_surface_line_width"
             || opt_key == "initial_layer_line_width"
-            || opt_key == "small_area_infill_flow_compensation") {
+            || opt_key == "small_area_infill_flow_compensation"
+            || opt_key == "lattice_angle_1"
+            || opt_key == "lattice_angle_2") {
             steps.emplace_back(posInfill);
         } else if (opt_key == "sparse_infill_pattern") {
             steps.emplace_back(posPrepareInfill);
@@ -3504,6 +3506,7 @@ void PrintObject::combine_infill()
                 ((infill_pattern == ipRectilinear   ||
                   infill_pattern == ipMonotonic     ||
                   infill_pattern == ipGrid          ||
+                  infill_pattern == ip2DLattice     ||
                   infill_pattern == ipLine          ||
                   infill_pattern == ipHoneycomb) ? 1.5f : 0.5f) *
                     layerms.back()->flow(frSolidInfill).scaled_width();

src/slic3r/GUI/ConfigManipulation.cpp

@@ -782,6 +782,10 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig *config, co
     toggle_line("interlocking_beam_layer_count", use_beam_interlocking);
     toggle_line("interlocking_depth", use_beam_interlocking);
     toggle_line("interlocking_boundary_avoidance", use_beam_interlocking);
+
+    bool lattice_options = config->opt_enum<InfillPattern>("sparse_infill_pattern") == InfillPattern::ip2DLattice;
+    for (auto el : { "lattice_angle_1", "lattice_angle_2"})
+        toggle_line(el, lattice_options);
 }
 
 void ConfigManipulation::update_print_sla_config(DynamicPrintConfig* config, const bool is_global_config/* = false*/)

src/slic3r/GUI/GUI_Factories.cpp

@@ -105,7 +105,7 @@ std::map<std::string, std::vector<SimpleSettingData>>  SettingsFactory::PART_CAT
                     }},
     { L("Strength"), {{"wall_loops", "",1},{"top_shell_layers", L("Top Solid Layers"),1},{"top_shell_thickness", L("Top Minimum Shell Thickness"),1},
                     {"bottom_shell_layers", L("Bottom Solid Layers"),1}, {"bottom_shell_thickness", L("Bottom Minimum Shell Thickness"),1},
-                    {"sparse_infill_density", "",1},{"sparse_infill_pattern", "",1},{"infill_anchor", "",1},{"infill_anchor_max", "",1},{"top_surface_pattern", "",1},{"bottom_surface_pattern", "",1}, {"internal_solid_infill_pattern", "",1},
+                    {"sparse_infill_density", "",1},{"sparse_infill_pattern", "",1},{"lattice_angle_1", "",1},{"lattice_angle_2", "",1},{"infill_anchor", "",1},{"infill_anchor_max", "",1},{"top_surface_pattern", "",1},{"bottom_surface_pattern", "",1}, {"internal_solid_infill_pattern", "",1},
         {"infill_combination", "",1}, {"infill_combination_max_layer_height", "",1}, {"infill_wall_overlap", "",1},{"top_bottom_infill_wall_overlap", "",1}, {"solid_infill_direction", "",1}, {"rotate_solid_infill_direction", "",1}, {"infill_direction", "",1}, {"bridge_angle", "",1}, {"internal_bridge_angle", "",1}, {"minimum_sparse_infill_area", "",1}
                     }},
     { L("Speed"), {{"outer_wall_speed", "",1},{"inner_wall_speed", "",2},{"sparse_infill_speed", "",3},{"top_surface_speed", "",4}, {"internal_solid_infill_speed", "",5},

src/slic3r/GUI/Tab.cpp

@@ -2138,6 +2138,8 @@ void TabPrint::build()
         optgroup = page->new_optgroup(L("Infill"), L"param_infill");
         optgroup->append_single_option_line("sparse_infill_density");
         optgroup->append_single_option_line("sparse_infill_pattern", "fill-patterns#infill types and their properties of sparse");
+        optgroup->append_single_option_line("lattice_angle_1");
+        optgroup->append_single_option_line("lattice_angle_2");
         optgroup->append_single_option_line("infill_anchor_max");
         optgroup->append_single_option_line("infill_anchor");
         optgroup->append_single_option_line("internal_solid_infill_pattern");