Added a new switch: ensure_vertical_shell_thickness

This enables a zig-zag infill similar to Cura or Simplify3D
on overhangs.

xs/src/libslic3r/PrintConfig.cpp

@@ -149,6 +149,13 @@ PrintConfigDef::PrintConfigDef()
     def->height = 120;
     def->default_value = new ConfigOptionString("M104 S0 ; turn off temperature\nG28 X0  ; home X axis\nM84     ; disable motors\n");
 
+    def = this->add("ensure_vertical_shell_thickness", coBool);
+    def->label = "Ensure vertical shell thickness";
+    def->category = "Layers and Perimeters";
+    def->tooltip = "Add solid infill near sloping surfaces to guarantee the vertical shell thickness (top+bottom solid layers).";
+    def->cli = "ensure-vertical-shell-thickness!";
+    def->default_value = new ConfigOptionBool(false);
+
     def = this->add("external_fill_pattern", coEnum);
     def->label = "Top/bottom fill pattern";
     def->category = "Infill";

xs/src/libslic3r/PrintConfig.hpp

@@ -206,6 +206,7 @@ class PrintRegionConfig : public virtual StaticPrintConfig
     ConfigOptionInt                 bottom_solid_layers;
     ConfigOptionFloat               bridge_flow_ratio;
     ConfigOptionFloat               bridge_speed;
+    ConfigOptionBool                ensure_vertical_shell_thickness;
     ConfigOptionEnum<InfillPattern> external_fill_pattern;
     ConfigOptionFloatOrPercent      external_perimeter_extrusion_width;
     ConfigOptionFloatOrPercent      external_perimeter_speed;
@@ -245,6 +246,7 @@ class PrintRegionConfig : public virtual StaticPrintConfig
         OPT_PTR(bottom_solid_layers);
         OPT_PTR(bridge_flow_ratio);
         OPT_PTR(bridge_speed);
+        OPT_PTR(ensure_vertical_shell_thickness);
         OPT_PTR(external_fill_pattern);
         OPT_PTR(external_perimeter_extrusion_width);
         OPT_PTR(external_perimeter_speed);

xs/src/libslic3r/PrintObject.cpp

@@ -247,7 +247,8 @@ PrintObject::invalidate_state_by_config_options(const std::vector<t_config_optio
             || *opt_key == "solid_infill_below_area"
             || *opt_key == "infill_extruder"
             || *opt_key == "solid_infill_extruder"
-            || *opt_key == "infill_extrusion_width") {
+            || *opt_key == "infill_extrusion_width"
+            || *opt_key == "ensure_vertical_shell_thickness") {
             steps.insert(posPrepareInfill);
         } else if (*opt_key == "external_fill_pattern"
             || *opt_key == "fill_angle"
@@ -359,6 +360,8 @@ void
 PrintObject::discover_vertical_shells()
 {
     for (size_t idx_region = 0; idx_region < this->_print->regions.size(); ++ idx_region) {
+        if (! this->_print->regions[idx_region]->config.ensure_vertical_shell_thickness.value)
+            continue;
         for (size_t idx_layer = 0; idx_layer < this->layers.size(); ++ idx_layer) {
             Layer* layer = this->layers[idx_layer];
             LayerRegion* layerm = layer->get_region(idx_region);

xs/src/libslic3r/SupportMaterial.hpp

@@ -1,9 +1,13 @@
 #ifndef slic3r_SupportMaterial_hpp_
 #define slic3r_SupportMaterial_hpp_
 
+#include "Flow.hpp"
+
 namespace Slic3r {
 
 class PrintObject;
+class PrintConfig;
+class PrintObjectConfig;
 
 // how much we extend support around the actual contact area
 #define SUPPORT_MATERIAL_MARGIN 1.5