#187 allow empty layer setting

resources/ui_layout/print.ui

@@ -80,6 +80,7 @@ group:label_width$8:Modifying slices
 	end_line
 group:Other
 	setting:clip_multipart_objects
+	setting:allow_empty_layers
 
 page:Infill:infill
 group:Infill

src/libslic3r/GCode.cpp

@@ -645,7 +645,7 @@ std::vector<GCode::LayerToPrint> GCode::collect_layers_to_print(const PrintObjec
             bool has_extrusions = (layer_to_print.object_layer && layer_to_print.object_layer->has_extrusions())
                                || (layer_to_print.support_layer && layer_to_print.support_layer->has_extrusions());
 
-            if (has_extrusions && layer_to_print.print_z() > maximal_print_z + 2. * EPSILON)
+            if (!object.print()->config().allow_empty_layers && has_extrusions && layer_to_print.print_z() > maximal_print_z + 2. * EPSILON)
                 throw std::runtime_error(_(L("Empty layers detected, the output would not be printable.")) + "\n\n" +
                     _(L("Object name")) + ": " + object.model_object()->name + "\n" + _(L("Print z")) + ": " +
                     std::to_string(layers_to_print.back().print_z()) + "\n\n" + _(L("This is "

src/libslic3r/PrintConfig.cpp

@@ -143,6 +143,14 @@ void PrintConfigDef::init_fff_params()
     // Maximum extruder temperature, bumped to 1500 to support printing of glass.
     const int max_temp = 1500;
 
+    def = this->add("allow_empty_layers", coBool);
+    def->label = L("Allow empty layers");
+    def->full_label = L("Allow empty layers");
+    def->category = OptionCategory::slicing;
+    def->tooltip = L("Do not prevent the gcode builder to trigger an exception if a full layer is empty and so the print will have to start from thin air afterward.");
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionBool(false));
+
     def = this->add("avoid_crossing_perimeters", coBool);
     def->label = L("Avoid crossing perimeters");
     def->category = OptionCategory::perimeter;

src/libslic3r/PrintConfig.hpp

@@ -952,6 +952,7 @@ public:
     double                          min_object_distance() const;
     static double                   min_object_distance(const ConfigBase *config);
 
+    ConfigOptionBool                allow_empty_layers;
     ConfigOptionBool                avoid_crossing_perimeters;
     ConfigOptionBool                avoid_crossing_not_first_layer;
     ConfigOptionPoints              bed_shape;
@@ -1033,6 +1034,7 @@ protected:
     {
         this->MachineEnvelopeConfig::initialize(cache, base_ptr);
         this->GCodeConfig::initialize(cache, base_ptr);
+        OPT_PTR(allow_empty_layers);
         OPT_PTR(avoid_crossing_perimeters);
         OPT_PTR(avoid_crossing_not_first_layer);
         OPT_PTR(bed_shape);

src/slic3r/GUI/Preset.cpp

@@ -426,7 +426,9 @@ const std::vector<std::string>& Preset::print_options()
         "bottom_solid_min_thickness",
         "extra_perimeters",
         "extra_perimeters_odd_layers",
-        "only_one_perimeter_top", "ensure_vertical_shell_thickness", "avoid_crossing_perimeters", 
+        "only_one_perimeter_top", "ensure_vertical_shell_thickness", 
+        "allow_empty_layers",
+        "avoid_crossing_perimeters", 
         "avoid_crossing_not_first_layer",
         "thin_perimeters",
         "thin_walls", "overhangs",