alternate extra wall: on odd layers

#89

src/libslic3r/PerimeterGenerator.cpp

@@ -273,9 +273,10 @@ void PerimeterGenerator::process()
     }
 
     surface_idx = 0;
+    const int extra_odd_perimeter = (config->extra_perimeters_odd_layers && layer_id % 2 == 1 ? 1:0);
     for (const Surface &surface : all_surfaces) {
         // detect how many perimeters must be generated for this island
-        int        loop_number = this->config->perimeters + surface.extra_perimeters - 1;  // 0-indexed loops
+        int        loop_number = this->config->perimeters + surface.extra_perimeters - 1 + extra_odd_perimeter;  // 0-indexed loops
         surface_idx++;
 
         if (this->config->only_one_perimeter_top && this->upper_slices == NULL){

src/libslic3r/PrintConfig.cpp

@@ -619,17 +619,27 @@ void PrintConfigDef::init_fff_params()
     def->enum_labels.push_back(L("Nearest"));
     def->enum_labels.push_back(L("Rear"));
     def->mode = comAdvanced;
-    def->set_default_value(new ConfigOptionEnum<SeamPosition>(spRear)); 
+    def->set_default_value(new ConfigOptionEnum<SeamPosition>(spRear));
-    
+
     def = this->add("extra_perimeters", coBool);
-    def->label = L("Extra perimeters if needed");
+    def->label = L("filling horizontal gaps on slopes");
+    def->full_label = L("Extra perimeters if needed");
     def->category = L("Layers and Perimeters");
     def->tooltip = L("Add more perimeters when needed for avoiding gaps in sloping walls. "
-                   "Slic3r keeps adding perimeters, until more than 70% of the loop immediately above "
+        "Slic3r keeps adding perimeters, until more than 70% of the loop immediately above "
-                   "is supported, and keep adding periemter until all overhangs are filled."
+        "is supported, and keep adding periemter until all overhangs are filled."
-                   "\n!! this is a very slow algorithm !!");
+        "\n!! this is a very slow algorithm !!");
     def->mode = comAdvanced;
-    def->set_default_value(new ConfigOptionBool(true));
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("extra_perimeters_odd_layers", coBool);
+    def->label = L("on odd layers");
+    def->full_label = L("Extra perimeter on odd layers");
+    def->category = L("Layers and Perimeters");
+    def->tooltip = L("Add one perimeter every odd layer. With this, infill is taken into sandwitch"
+        " and you may be able to reduce drastically the infill/perimeter overlap setting. ");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
 
     def = this->add("only_one_perimeter_top", coBool);
     def->label = "Only one perimeter on Top surfaces";

src/libslic3r/PrintConfig.hpp

@@ -587,6 +587,7 @@ public:
     ConfigOptionFloatOrPercent      external_perimeter_speed;
     ConfigOptionBool                external_perimeters_first;
     ConfigOptionBool                extra_perimeters;
+    ConfigOptionBool                extra_perimeters_odd_layers;
     ConfigOptionBool                only_one_perimeter_top;
     ConfigOptionFloat               fill_angle;
     ConfigOptionPercent             fill_density;
@@ -655,6 +656,7 @@ protected:
         OPT_PTR(external_perimeter_speed);
         OPT_PTR(external_perimeters_first);
         OPT_PTR(extra_perimeters);
+        OPT_PTR(extra_perimeters_odd_layers);
         OPT_PTR(only_one_perimeter_top);
         OPT_PTR(fill_angle);
         OPT_PTR(fill_density);

src/libslic3r/PrintObject.cpp

@@ -472,6 +472,7 @@ bool PrintObject::invalidate_state_by_config_options(const std::vector<t_config_
     for (const t_config_option_key &opt_key : opt_keys) {
         if (   opt_key == "perimeters"
             || opt_key == "extra_perimeters"
+            || opt_key == "extra_perimeters_odd_layers"
             || opt_key == "gap_fill"
             || opt_key == "gap_fill_speed"
             || opt_key == "overhangs"

src/slic3r/GUI/ConfigManipulation.cpp

@@ -241,7 +241,7 @@ void ConfigManipulation::update_print_fff_config(DynamicPrintConfig* config, con
 void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig* config)
 {
     bool have_perimeters = config->opt_int("perimeters") > 0;
-    for (auto el : { "extra_perimeters", "only_one_perimeter_top", "ensure_vertical_shell_thickness", "thin_walls", "overhangs",
+    for (auto el : { "extra_perimeters", "extra_perimeters_odd_layers", "only_one_perimeter_top", "ensure_vertical_shell_thickness", "thin_walls", "overhangs",
         "seam_position", "external_perimeters_first", "external_perimeter_extrusion_width",
         "perimeter_speed", "small_perimeter_speed", "external_perimeter_speed", "perimeter_loop", "perimeter_loop_seam" })
         toggle_field(el, have_perimeters);

src/slic3r/GUI/Preset.cpp

@@ -379,7 +379,9 @@ const std::vector<std::string>& Preset::print_options()
 {    
     static std::vector<std::string> s_opts {
         "layer_height", "first_layer_height", "perimeters", "spiral_vase", "slice_closing_radius", "top_solid_layers", "bottom_solid_layers", 
-        "extra_perimeters", "only_one_perimeter_top", "ensure_vertical_shell_thickness", "avoid_crossing_perimeters", "thin_walls", "overhangs", 
+        "extra_perimeters",
+        "extra_perimeters_odd_layers",
+        "only_one_perimeter_top", "ensure_vertical_shell_thickness", "avoid_crossing_perimeters", "thin_walls", "overhangs", 
         "overhangs_width",
         "seam_position", "external_perimeters_first", "fill_density"
         , "fill_pattern"

src/slic3r/GUI/PresetHints.cpp

@@ -267,7 +267,7 @@ std::string PresetHints::recommended_thin_wall_thickness(const PresetBundle &pre
     
     if (num_perimeters > 0) {
         int num_lines = std::min(num_perimeters * 2, 10);
-        out += (boost::format(_utf8(L("Recommended object min thin wall thickness for layer height %.2f and"))) % layer_height).str() + " ";
+        out += (boost::format(_utf8(L("Recommended object min wall thickness for layer height %.2f and"))) % layer_height).str() + " ";
         // Start with the width of two closely spaced 
         double width = external_perimeter_flow.width + external_perimeter_flow.spacing();
         for (int i = 2; i <= num_lines; thin_walls ? ++ i : i += 2) {

src/slic3r/GUI/Tab.cpp

@@ -1051,7 +1051,10 @@ void TabPrint::build()
         optgroup->append_single_option_line("enforce_full_fill_volume");
 
 		optgroup = page->new_optgroup(_(L("Quality (slower slicing)")));
-		optgroup->append_single_option_line("extra_perimeters");
+        line = { _(L("Extra perimeters")), "" };
+        line.append_option(optgroup->get_option("extra_perimeters"));
+        line.append_option(optgroup->get_option("extra_perimeters_odd_layers"));
+        optgroup->append_line(line);
 		optgroup->append_single_option_line("only_one_perimeter_top");
 		optgroup->append_single_option_line("ensure_vertical_shell_thickness");
 		optgroup->append_single_option_line("avoid_crossing_perimeters");