Add a "between extrusion role" gcode input window, to let insert gcode inside a layer and not only at the begin and the end.

#108

src/libslic3r/GCode.cpp

@@ -2909,6 +2909,15 @@ std::string GCode::_before_extrude(const ExtrusionPath &path, const std::string
     double F = speed * 60;  // convert mm/sec to mm/min
 
     // extrude arc or line
+    if (path.role() != m_last_extrusion_role) {
+        DynamicConfig config;
+        config.set_key_value("extrusion_role", new ConfigOptionString(extrusion_role_to_string_for_parser(path.role())));
+        config.set_key_value("layer_num", new ConfigOptionInt(m_layer_index + 1));
+        config.set_key_value("layer_z", new ConfigOptionFloat(m_config.z_offset.value));
+        gcode += this->placeholder_parser_process("feature_gcode",
+            m_config.feature_gcode.value, m_writer.extruder()->id(), &config)
+            + "\n";
+    }
     if (m_enable_extrusion_role_markers) {
         if (path.role() != m_last_extrusion_role) {
             char buf[32];
@@ -3266,4 +3275,40 @@ void GCode::ObjectByExtruder::Island::Region::append(const std::string& type, co
         perimeters_or_infills_overrides->push_back(copies_extruder);
 }
 
+std::string
+GCode::extrusion_role_to_string_for_parser(const ExtrusionRole & role) {
+    switch (role) {
+    case erPerimeter:
+        return "Perimeter";
+    case erExternalPerimeter:
+        return "ExternalPerimeter";
+    case erOverhangPerimeter:
+        return "OverhangPerimeter";
+    case erInternalInfill:
+        return "InternalInfill";
+    case erSolidInfill:
+        return "SolidInfill";
+    case erTopSolidInfill:
+        return "TopSolidInfill";
+    case erBridgeInfill:
+        return "BridgeInfill";
+    case erGapFill:
+        return "GapFill";
+    case erSkirt:
+        return "Skirt";
+    case erSupportMaterial:
+        return "SupportMaterial";
+    case erSupportMaterialInterface:
+        return "SupportMaterialInterface";
+    case erWipeTower:
+        return "WipeTower";
+    case erCustom:
+    case erMixed:
+    case erCount:
+    case erNone:
+    default:
+        return "Mixed";
+    }
+}
+
 }   // namespace Slic3r

src/libslic3r/GCode.hpp

@@ -182,6 +182,7 @@ public:
     // inside the generated string and after the G-code export finishes.
     std::string     placeholder_parser_process(const std::string &name, const std::string &templ, unsigned int current_extruder_id, const DynamicConfig *config_override = nullptr);
     bool            enable_cooling_markers() const { return m_enable_cooling_markers; }
+    std::string     extrusion_role_to_string_for_parser(const ExtrusionRole &);
 
     // For Perl bindings, to be used exclusively by unit tests.
     unsigned int    layer_count() const { return m_layer_count; }

src/libslic3r/PrintConfig.cpp

@@ -1477,8 +1477,8 @@ void PrintConfigDef::init_fff_params()
     def = this->add("layer_gcode", coString);
     def->label = L("After layer change G-code");
     def->tooltip = L("This custom code is inserted at every layer change, right after the Z move "
-                   "and before the extruder moves to the first layer point. Note that you can use "
+        "and before the extruder moves to the first layer point. Note that you can use "
-                   "placeholder variables for all Slic3r settings as well as [layer_num] and [layer_z].");
+        "placeholder variables for all Slic3r settings as well as [layer_num] and [layer_z].");
     def->cli = "after-layer-gcode|layer-gcode";
     def->multiline = true;
     def->full_width = true;
@@ -1486,6 +1486,19 @@ void PrintConfigDef::init_fff_params()
     def->mode = comExpert;
     def->set_default_value(new ConfigOptionString(""));
 
+    def = this->add("feature_gcode", coString);
+    def->label = L("After layer change G-code");
+    def->tooltip = L("This custom code is inserted at every extrusion type change."
+        "Note that you can use placeholder variables for all Slic3r settings as well as [extrusion_role], [layer_num] and [layer_z] that can take these string values:"
+        " { Perimeter, ExternalPerimeter, OverhangPerimeter, InternalInfill, SolidInfill, TopSolidInfill, BridgeInfill, GapFill, Skirt, SupportMaterial, SupportMaterialInterface, WipeTower, Mixed }."
+        " Mixed is only used when the role of the extrusion is not unique, not exactly inside an other category or not known.");
+    def->cli = "feature-gcode";
+    def->multiline = true;
+    def->full_width = true;
+    def->height = 5;
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionString(""));
+
     def = this->add("exact_last_layer_height", coBool);
     def->label = L("Exact last layer height");
     def->category = L("Layers and Perimeters");

src/libslic3r/PrintConfig.hpp

@@ -799,6 +799,7 @@ public:
     ConfigOptionEnum<GCodeFlavor>   gcode_flavor;
     ConfigOptionBool                gcode_label_objects;
     ConfigOptionString              layer_gcode;
+    ConfigOptionString              feature_gcode;
     ConfigOptionFloat               max_print_speed;
     ConfigOptionFloat               max_volumetric_speed;
 #ifdef HAS_PRESSURE_EQUALIZER
@@ -890,6 +891,7 @@ protected:
         OPT_PTR(gcode_flavor);
         OPT_PTR(gcode_label_objects);
         OPT_PTR(layer_gcode);
+        OPT_PTR(feature_gcode);
         OPT_PTR(max_print_speed);
         OPT_PTR(max_volumetric_speed);
 #ifdef HAS_PRESSURE_EQUALIZER

src/slic3r/GUI/Preset.cpp

@@ -494,6 +494,7 @@ const std::vector<std::string>& Preset::printer_options()
             "use_firmware_retraction", "use_volumetric_e", "variable_layer_height",
             "host_type", "print_host", "printhost_apikey", "printhost_cafile",
             "single_extruder_multi_material", "start_gcode", "end_gcode", "before_layer_gcode", "layer_gcode", "toolchange_gcode",
+            "feature_gcode",
             "between_objects_gcode", "printer_vendor", "printer_model", "printer_variant", "printer_notes", "cooling_tube_retraction",
             "cooling_tube_length", "high_current_on_filament_swap", "parking_pos_retraction", "extra_loading_move", "max_print_height", 
             "default_print_profile", "inherits",

src/slic3r/GUI/Tab.cpp

@@ -2074,6 +2074,12 @@ void TabPrinter::build_fff()
 		option.opt.full_width = true;
         option.opt.height = gcode_field_height;//150;
 		optgroup->append_single_option_line(option);
+
+		optgroup = page->new_optgroup(_(L("Between extrusion role change G-code")), 0);
+		option = optgroup->get_option("feature_gcode");
+		option.opt.full_width = true;
+        option.opt.height = gcode_field_height;//150;
+		optgroup->append_single_option_line(option);
 	
 	page = add_options_page(_(L("Notes")), "note.png");
 		optgroup = page->new_optgroup(_(L("Notes")), 0);