Expose lightning infill angles (#13848)

* expose lightning infill angles

Update PrintObject.cpp

* Update src/libslic3r/PrintConfig.cpp

* Apply suggestions from code review

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Update GUI_Factories.cpp

* Fix lightning infill angles to 45 degrees for supports

Updated lightning infill angles to fixed values for consistency.

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

src/libslic3r/Fill/Lightning/Generator.cpp

@@ -89,9 +89,9 @@ Generator::Generator(const PrintObject &print_object, const std::function<void()
     
     m_supporting_radius = coord_t(m_infill_extrusion_width) * 100 * n_multiline / region_config.sparse_infill_density;
 
-    const double lightning_infill_overhang_angle      = M_PI / 4; // 45 degrees
-    const double lightning_infill_prune_angle         = M_PI / 4; // 45 degrees
-    const double lightning_infill_straightening_angle = M_PI / 4; // 45 degrees
+    const double lightning_infill_overhang_angle      = region_config.lightning_overhang_angle.value * M_PI / 180.0;
+    const double lightning_infill_prune_angle         = region_config.lightning_prune_angle.value * M_PI / 180.0;
+    const double lightning_infill_straightening_angle = region_config.lightning_straightening_angle.value * M_PI / 180.0;
     m_wall_supporting_radius                          = coord_t(layer_thickness * std::tan(lightning_infill_overhang_angle));
     m_prune_length                                    = coord_t(layer_thickness * std::tan(lightning_infill_prune_angle));
     m_straightening_max_distance                      = coord_t(layer_thickness * std::tan(lightning_infill_straightening_angle));
@@ -128,7 +128,7 @@ Generator::Generator(PrintObject* m_object, std::vector<Polygons>& contours, std
     //TODO: decide whether enable density controller in advanced options or not
     density = std::max(0.15f, density);
     m_supporting_radius = coord_t(m_infill_extrusion_width) / density;
-
+    // Keep support-lightning behavior fixed and independent of user print-region angles.
     const double lightning_infill_overhang_angle = M_PI / 4; // 45 degrees
     const double lightning_infill_prune_angle = M_PI / 4; // 45 degrees
     const double lightning_infill_straightening_angle = M_PI / 4; // 45 degrees

src/libslic3r/Preset.cpp

@@ -1005,6 +1005,9 @@ static std::vector<std::string> s_Preset_print_options{
     "lateral_lattice_angle_1",
     "lateral_lattice_angle_2",
     "infill_overhang_angle",
+    "lightning_overhang_angle",
+    "lightning_prune_angle",
+    "lightning_straightening_angle",
     "top_surface_pattern",
     "bottom_surface_pattern",
     "infill_direction",

src/libslic3r/PrintConfig.cpp

@@ -3047,6 +3047,36 @@ void PrintConfigDef::init_fff_params()
     def->mode     = comAdvanced;
     def->set_default_value(new ConfigOptionFloat(60));
 
+    def           = this->add("lightning_overhang_angle", coFloat);
+    def->label    = L("Lightning overhang angle");
+    def->category = L("Strength");
+    def->tooltip  = L("Maximum overhang angle for Lightning infill support propagation.");
+    def->sidetext = u8"°";
+    def->min      = 5;
+    def->max      = 85;
+    def->mode     = comExpert;
+    def->set_default_value(new ConfigOptionFloat(45));
+
+    def           = this->add("lightning_prune_angle", coFloat);
+    def->label    = L("Prune angle");
+    def->category = L("Strength");
+    def->tooltip  = L("Controls how aggressively short or unsupported Lightning branches are pruned. This angle is converted internally to a per-layer distance.");
+    def->sidetext = u8"°";
+    def->min      = 5;
+    def->max      = 85;
+    def->mode     = comExpert;
+    def->set_default_value(new ConfigOptionFloat(45));
+
+    def           = this->add("lightning_straightening_angle", coFloat);
+    def->label    = L("Straightening angle");
+    def->category = L("Strength");
+    def->tooltip  = L("Maximum straightening angle used to simplify Lightning branches.");
+    def->sidetext = u8"°";
+    def->min      = 5;
+    def->max      = 85;
+    def->mode     = comExpert;
+    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

@@ -1103,6 +1103,9 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionFloat,                lateral_lattice_angle_1))
     ((ConfigOptionFloat,                lateral_lattice_angle_2))
     ((ConfigOptionFloat,                infill_overhang_angle))
+    ((ConfigOptionFloat,                lightning_overhang_angle))
+    ((ConfigOptionFloat,                lightning_prune_angle))
+    ((ConfigOptionFloat,                lightning_straightening_angle))
     ((ConfigOptionBool,                 align_infill_direction_to_model))
     ((ConfigOptionString,               extra_solid_infills))
     ((ConfigOptionEnum<FuzzySkinType>,  fuzzy_skin))

src/libslic3r/PrintObject.cpp

@@ -1300,6 +1300,9 @@ bool PrintObject::invalidate_state_by_config_options(
                    || opt_key == "infill_shift_step"
                    || opt_key == "sparse_infill_rotate_template"
                    || opt_key == "solid_infill_rotate_template"
+                   || opt_key == "lightning_overhang_angle"
+                   || opt_key == "lightning_prune_angle"
+                   || opt_key == "lightning_straightening_angle"
                    || opt_key == "skeleton_infill_density"
                    || opt_key == "skin_infill_density"
                    || opt_key == "infill_lock_depth"