Partial implementation #1405: minimum shell thickness option (#3885)

* Added Minimum shell thickness option

-Added the option to libslic3r
-Created some of the necessary checks for illegal values

* Enforce min_shell_thickness as 0 when spiral vase is enabled

-This could be switched to match the extrusion width, but we already know there will only be 1 perimeter so this is probably more logical

* Feature is implemented

-Added a method in PerimeterGenerator to determine the amount of perimeters needed to meet min_shell_thickness

* Added a test in perimeters.t

* Fixed styling as requested

-Removed the magic number in PerimeterGenerator::num_loops()
-Added more test cases in perimeters.t
-Added documentation of the new feature in slic3r.pl and README.md

* Implemented requested changes

-Removed the num_loops function from PerimeterGenerator
-Added a scalled min_shell_thickness variable to PerimeterGenerator
-Changed the loop_number logic to use a previously defined variable loops

* Resolved more implementation issues

-Added min shell to invalidate state method
-Created additional checks in PresetEditor and LayerRegion for min shell
-Fixed the tooltip to be more descriptive

README.md

@@ -216,6 +216,7 @@ Contributions by Henrik Brix Andersen, Vojtech Bubnik, Nicolas Dandrimont, Mark
         --perimeters        Number of perimeters/horizontal skins (range: 0+, default: 3)
         --top-solid-layers  Number of solid layers to do for top surfaces (range: 0+, default: 3)
         --bottom-solid-layers  Number of solid layers to do for bottom surfaces (range: 0+, default: 3)
+        --min-shell-thickness  Minimum thickness of all solid shells (range: 0+, default: 0)
         --solid-layers      Shortcut for setting the two options above at once
         --fill-density      Infill density (range: 0%-100%, default: 40%)
         --fill-angle        Infill angle in degrees (range: 0-90, default: 45)

lib/Slic3r/Config.pm

@@ -176,6 +176,9 @@ sub validate {
     die "Invalid value for --filament-diameter\n"
         if grep $_ < 1, @{$self->filament_diameter};
     
+    die "Invalid value for --min-shell-thickness\n"
+        if $self->min_shell_thickness < 0;
+
     # --nozzle-diameter
     die "Invalid value for --nozzle-diameter\n"
         if grep $_ < 0, @{$self->nozzle_diameter};
@@ -254,6 +257,9 @@ sub validate {
         die "Can't make less than one perimeter when spiral vase mode is enabled\n"
             if $self->perimeters < 1;
 
+        die "Minimum shell thickness should be 0 when spiral vase mode is enabled\n"
+            if $self->min_shell_thickness > 0;
+
         die "Spiral vase mode can only print hollow objects, so you need to set Fill density to 0\n"
             if $self->fill_density > 0;
         

lib/Slic3r/GUI/PresetEditor.pm

@@ -438,7 +438,7 @@ sub options {
         layer_height first_layer_height
         adaptive_slicing adaptive_slicing_quality match_horizontal_surfaces
         perimeters spiral_vase
-        top_solid_layers bottom_solid_layers
+        top_solid_layers min_shell_thickness bottom_solid_layers
         extra_perimeters avoid_crossing_perimeters thin_walls overhangs
         seam_position external_perimeters_first
         fill_density fill_pattern top_infill_pattern bottom_infill_pattern fill_gaps
@@ -521,6 +521,7 @@ sub build {
         {
             my $optgroup = $page->new_optgroup('Vertical shells');
             $optgroup->append_single_option_line('perimeters');
+            $optgroup->append_single_option_line('min_shell_thickness');
             $optgroup->append_single_option_line('spiral_vase');
         }
         {
@@ -800,8 +801,9 @@ sub _update {
     my $opt_key = $key;
     $opt_key = "all_keys" if (length($key // '') == 0); 
     my $config = $self->{config};
-    if (any { /$opt_key/ } qw(all_keys spiral_vase perimeters top_solid_layers fill_density support_material)) {
+
-        if ($config->spiral_vase && !($config->perimeters == 1 && $config->top_solid_layers == 0 && $config->fill_density == 0 && $config->support_material == 0)) {
+    if (any { /$opt_key/ } qw(all_keys spiral_vase perimeters top_solid_layers fill_density support_material min_shell_thickness)) {
+        if ($config->spiral_vase && !($config->perimeters == 1 && $config->min_shell_thickness == 0 & $config->top_solid_layers == 0 && $config->fill_density == 0 && $config->support_material == 0)) {
             my $dialog = Wx::MessageDialog->new($self,
                 "The Spiral Vase mode requires:\n"
                 . "- one perimeter\n"
@@ -813,6 +815,7 @@ sub _update {
             if ($dialog->ShowModal() == wxID_YES) {
                 my $new_conf = Slic3r::Config->new;
                 $new_conf->set("perimeters", 1);
+                $new_conf->set("min_shell_thickness", 0);
                 $new_conf->set("top_solid_layers", 0);
                 $new_conf->set("fill_density", 0);
                 $new_conf->set("support_material", 0);
@@ -874,8 +877,7 @@ sub _update {
         }
     }
 
-    
+    my $have_perimeters = ($config->perimeters > 0) || ($config->min_shell_thickness > 0);
-    my $have_perimeters = $config->perimeters > 0;
     if (any { /$opt_key/ } qw(all_keys perimeters)) {
         $self->get_field($_)->toggle($have_perimeters)
             for qw(extra_perimeters thin_walls overhangs seam_position external_perimeters_first
@@ -917,7 +919,8 @@ sub _update {
         $self->get_field('gap_fill_speed')->toggle($have_perimeters && $have_infill && $config->fill_gaps);
     }
 
-    my $have_top_solid_infill = $config->top_solid_layers > 0;
+    my $have_top_solid_infill = ($config->top_solid_layers > 0) || ($config->min_shell_thickness > 0);
+
     $self->get_field($_)->toggle($have_top_solid_infill)
         for qw(top_infill_extrusion_width top_solid_infill_speed);
 

slic3r.pl

@@ -439,6 +439,7 @@ $j
     --perimeters        Number of perimeters/horizontal skins (range: 0+, default: $config->{perimeters})
     --top-solid-layers  Number of solid layers to do for top surfaces (range: 0+, default: $config->{top_solid_layers})
     --bottom-solid-layers  Number of solid layers to do for bottom surfaces (range: 0+, default: $config->{bottom_solid_layers})
+    --min-shell-thickness  Minimum thickness of all solid shells (range: 0+, default: 0)
     --solid-layers      Shortcut for setting the two options above at once
     --fill-density      Infill density (range: 0%-100%, default: $config->{fill_density}%)
     --fill-angle        Infill angle in degrees (range: 0-90, default: $config->{fill_angle})

t/perimeters.t

@@ -1,4 +1,4 @@
-use Test::More tests => 63;
+use Test::More tests => 66;
 use strict;
 use warnings;
 
@@ -313,6 +313,54 @@ use Slic3r::Test;
     ok !(grep { $_ % $config->perimeters } values %perimeters), 'no superfluous extra perimeters';
 }
 
+{
+    my $config = Slic3r::Config->new_from_defaults;
+    $config->set('skirts', 0);
+    $config->set('perimeters', 3);
+    $config->set('min_shell_thickness', 3);
+    $config->set('layer_height', 0.4);
+    $config->set('first_layer_height', 0.35);
+    $config->set('extra_perimeters', 0);
+    $config->set('first_layer_extrusion_width', 0.5);
+    $config->set('perimeter_extrusion_width', 0.5);
+    $config->set('external_perimeter_extrusion_width', 0.5);
+    $config->set('cooling', 0);                     # to prevent speeds from being altered
+    $config->set('first_layer_speed', '100%');      # to prevent speeds from being altered
+    $config->set('perimeter_speed', 99);
+    $config->set('external_perimeter_speed', 99);
+    $config->set('small_perimeter_speed', 99);
+    $config->set('thin_walls', 0);
+    
+    my $test = sub {
+        my $print = Slic3r::Test::init_print('ipadstand', config => $config);
+        my %perimeters = ();  # z => number of loops
+        my $in_loop = 0;
+        Slic3r::GCode::Reader->new->parse(Slic3r::Test::gcode($print), sub {
+            my ($self, $cmd, $args, $info) = @_;
+            
+            if ($info->{extruding} && $info->{dist_XY} > 0 && ($args->{F} // $self->F) == $config->perimeter_speed*60) {
+                $perimeters{$self->Z}++ if !$in_loop;
+                $in_loop = 1;
+            } else {
+                $in_loop = 0;
+            }
+        });
+        ok !(grep { $_ % $config->min_shell_thickness/$config->perimeter_extrusion_width } values %perimeters), 'should be 6 perimeters';
+    };
+
+    $test->();
+
+    $config->set('first_layer_extrusion_width', 0.54);
+    $config->set('perimeter_extrusion_width', 0.54);
+    $config->set('external_perimeter_extrusion_width', 0.54);
+    $test->();
+
+    $config->set('first_layer_extrusion_width', 0.59);
+    $config->set('perimeter_extrusion_width', 0.51);
+    $config->set('external_perimeter_extrusion_width', 0.51);
+    $test->();
+}
+
 {
     my $config = Slic3r::Config->new_from_defaults;
     $config->set('nozzle_diameter', [0.4]);

xs/src/libslic3r/LayerRegion.cpp

@@ -237,6 +237,7 @@ LayerRegion::prepare_fill_surfaces()
         the only meaningful information returned by psPerimeters. */
     
     // if no solid layers are requested, turn top/bottom surfaces to internal
+    if (this->region()->config.min_shell_thickness == 0) {
         if (this->region()->config.top_solid_layers == 0) {
             for (Surfaces::iterator surface = this->fill_surfaces.surfaces.begin(); surface != this->fill_surfaces.surfaces.end(); ++surface) {
                 if (surface->surface_type == stTop) {
@@ -254,6 +255,7 @@ LayerRegion::prepare_fill_surfaces()
                     surface->surface_type = stInternal;
             }
         }
+    }
         
     // turn too small internal regions into solid regions according to the user setting
     const float &fill_density = this->region()->config.fill_density;

xs/src/libslic3r/PerimeterGenerator.cpp

@@ -39,6 +39,9 @@ PerimeterGenerator::process()
     coord_t min_spacing         = pspacing      * (1 - INSET_OVERLAP_TOLERANCE);
     coord_t ext_min_spacing     = ext_pspacing  * (1 - INSET_OVERLAP_TOLERANCE);
 
+    // minimum shell thickness
+    coord_t min_shell_thickness = scale_(this->config->min_shell_thickness);
+    
     // prepare grown lower layer slices for overhang detection
     if (this->lower_slices != NULL && this->config->overhangs) {
         // We consider overhang any part where the entire nozzle diameter is not supported by the
@@ -54,7 +57,20 @@ PerimeterGenerator::process()
     for (Surfaces::const_iterator surface = this->slices->surfaces.begin();
         surface != this->slices->surfaces.end(); ++surface) {
         // detect how many perimeters must be generated for this island
-        const int loop_number = this->config->perimeters + surface->extra_perimeters -1;  // 0-indexed loops
+        int loops = this->config->perimeters + surface->extra_perimeters;
+
+        // If the user has defined a minimum shell thickness compute the number of loops needed to satisfy
+        if (min_shell_thickness > 0) {
+            int min_loops = 1;
+
+            min_loops += ceil(((float)min_shell_thickness-ext_pwidth)/pwidth);
+
+            if (loops < min_loops)
+                loops = min_loops;
+        }
+
+        const int loop_number = loops-1;  // 0-indexed loops
+        
 
         Polygons gaps;
         

xs/src/libslic3r/PrintConfig.cpp

@@ -827,6 +827,16 @@ PrintConfigDef::PrintConfigDef()
     def->max = 100;
     def->default_value = new ConfigOptionInt(35);
 
+
+    def = this->add("min_shell_thickness", coFloat);
+    def->label = "Minimum shell thickness";
+    def->category = "Layers and Perimeters";
+    def->sidetext = "mm";
+    def->tooltip = "Alternative method of configuring perimeters and top/bottom layers. If this is above 0 extra perimeters and solid layers will be generated when necessary";
+    def->cli = "min-shell-thickness=f";
+    def->min = 0;
+    def->default_value = new ConfigOptionFloat(0);
+
     def = this->add("min_layer_height", coFloats);
     def->label = "Min";
     def->tooltip = "This is the lowest printable layer height for this extruder and limits the resolution for adaptive slicing. Typical values are 0.1 or 0.05.";

xs/src/libslic3r/PrintConfig.hpp

@@ -255,6 +255,7 @@ class PrintRegionConfig : public virtual StaticPrintConfig
     ConfigOptionInt                 infill_every_layers;
     ConfigOptionFloatOrPercent      infill_overlap;
     ConfigOptionFloat               infill_speed;
+    ConfigOptionFloat               min_shell_thickness;
     ConfigOptionBool                overhangs;
     ConfigOptionInt                 perimeter_extruder;
     ConfigOptionFloatOrPercent      perimeter_extrusion_width;
@@ -296,6 +297,7 @@ class PrintRegionConfig : public virtual StaticPrintConfig
         OPT_PTR(infill_every_layers);
         OPT_PTR(infill_overlap);
         OPT_PTR(infill_speed);
+        OPT_PTR(min_shell_thickness);
         OPT_PTR(overhangs);
         OPT_PTR(perimeter_extruder);
         OPT_PTR(perimeter_extrusion_width);

xs/src/libslic3r/PrintRegion.cpp

@@ -76,6 +76,7 @@ PrintRegion::invalidate_state_by_config(const PrintConfigBase &config)
     for (const t_config_option_key &opt_key : diff) {
         if (opt_key == "perimeters"
             || opt_key == "extra_perimeters"
+            || opt_key == "min_shell_thickness"
             || opt_key == "gap_fill_speed"
             || opt_key == "overhangs"
             || opt_key == "first_layer_extrusion_width"
@@ -98,6 +99,7 @@ PrintRegion::invalidate_state_by_config(const PrintConfigBase &config)
             || opt_key == "solid_infill_every_layers"
             || opt_key == "bottom_solid_layers"
             || opt_key == "top_solid_layers"
+            || opt_key == "min_shell_thickness"
             || opt_key == "infill_extruder"
             || opt_key == "solid_infill_extruder"
             || opt_key == "infill_extrusion_width") {