Feature: try to match horizontal surfaces with adaptive slicing

lib/Slic3r/AdaptiveSlicing.pm

@@ -6,6 +6,7 @@ use Slic3r::Geometry qw(X Y Z triangle_normal scale unscale);
 
 # public
 has 'mesh' => (is => 'ro', required => 1);
+has 'size' => (is => 'ro', required => 1);
 
 #private
 has 'normal_z'  			=> (is => 'ro', default => sub { [] }); # facet_id => [normal];
@@ -158,5 +159,37 @@ sub _facet_cusp_height {
 	return $cusp;
 }
 
+# Returns the distance to the next horizontal facet in Z-dir 
+# to consider horizontal object features in slice thickness
+sub horizontal_facet_distance {
+	my $self = shift;
+	my ($z, $max_height) = @_;
+	$max_height = scale $max_height;
+	
+	my $ordered_id = $self->current_facet;
+	while ($ordered_id <= $#{$self->ordered_facets}) {
+		
+		# facet's minimum is higher than max forward distance -> end loop
+		if($self->ordered_facets->[$ordered_id]->[1] > $z+$max_height) {
+			last;
+		}
+		 
+		# min_z == max_z -> horizontal facet
+		if($self->ordered_facets->[$ordered_id]->[1] > $z) {
+			if($self->ordered_facets->[$ordered_id]->[1] == $self->ordered_facets->[$ordered_id]->[2]) {
+				return unscale $self->ordered_facets->[$ordered_id]->[1] - $z;
+			}
+		}
+		
+		$ordered_id++;
+	}
+	
+	# objects maximum?
+	if($z + $max_height > $self->size) {
+		return 	max(unscale $self->size - $z, 0);
+	}
+	return unscale $max_height;
+}
+
 
 1;

lib/Slic3r/GUI/Tab.pm

@@ -455,7 +455,7 @@ sub build {
     my $self = shift;
     
     $self->init_config_options(qw(
-    	adaptive_slicing cusp_value
+    	adaptive_slicing cusp_value match_horizontal_surfaces
         layer_height first_layer_height
         perimeters spiral_vase
         top_solid_layers bottom_solid_layers
@@ -504,6 +504,7 @@ sub build {
             $optgroup->append_single_option_line('first_layer_height');
             $optgroup->append_single_option_line('adaptive_slicing');
             $optgroup->append_single_option_line('cusp_value');
+            $optgroup->append_single_option_line('match_horizontal_surfaces');
         }
         {
             my $optgroup = $page->new_optgroup('Vertical shells');
@@ -787,7 +788,7 @@ sub _update {
 
     my $have_adaptive_slicing = $config->adaptive_slicing;
     $self->get_field($_)->toggle($have_adaptive_slicing)
-        for qw(cusp_value);
+        for qw(cusp_value match_horizontal_surfaces);
     $self->get_field($_)->toggle(!$have_adaptive_slicing)
         for qw(layer_height);
     

lib/Slic3r/Print/Object.pm

@@ -108,7 +108,8 @@ sub slice {
 			    }
 	        	
 				$adaptive_slicing[$region_id] = Slic3r::AdaptiveSlicing->new(
-					mesh => $mesh
+					mesh => $mesh,
+					size => $self->size->z
 				);
 			}
 			
@@ -136,6 +137,24 @@ sub slice {
        			for my $region_id (0 .. ($self->region_count - 1)) {
 	       			# get cusp height
 	       			my $cusp_height = $adaptive_slicing[$region_id]->cusp_height(scale $slice_z, $cusp_value, $min_height, $max_height);
+	       			
+	       			# check for horizontal features and object size
+	       			if($self->config->get_value('match_horizontal_surfaces')) {
+				       	my $horizontal_dist = $adaptive_slicing[$region_id]->horizontal_facet_distance(scale $slice_z+$cusp_height, $min_height);
+				       	if(($horizontal_dist < $min_height) && ($horizontal_dist > 0)) {
+				       		Slic3r::debugf "Horizontal feature ahead, distance: %f\n", $horizontal_dist;
+				       		# can we shrink the current layer a bit?
+				       		if($cusp_height-($min_height-$horizontal_dist) > $min_height) {
+				       			# yes we can
+				       			$cusp_height = $cusp_height-($min_height-$horizontal_dist);
+				       			Slic3r::debugf "Shrink layer height to %f\n", $cusp_height;
+				       		}else{
+				       			# no, current layer would become too thin
+				       			$cusp_height = $cusp_height+$horizontal_dist;
+				       			Slic3r::debugf "Widen layer height to %f\n", $cusp_height;
+				       		}
+				       	}
+	       			}
 
 			       	$height = ($id == 0)
                 		? $self->config->get_value('first_layer_height')

t/adaptive_slicing.t

@@ -46,7 +46,8 @@ my $test = sub {
 my $print = Slic3r::Test::init_print('slopy_cube', config => $config);
 $print->models->[0]->mesh->repair();
 my $adaptive_slicing = Slic3r::AdaptiveSlicing->new(
-	mesh => Slic3r::Test::mesh('slopy_cube')
+	mesh => Slic3r::Test::mesh('slopy_cube'),
+	size => 20
 );
 
 

xs/src/libslic3r/PrintConfig.cpp

@@ -585,6 +585,12 @@ PrintConfigDef::PrintConfigDef()
     def->min = 0;
     def->default_value = new ConfigOptionFloat(0.3);
 
+    def = this->add("match_horizontal_surfaces", coBool);
+    def->label = "Match horizontal surfaces";
+    def->tooltip = "Try to match horizontal surfaces during the slicing process. Matching is not guaranteed, very small surfaces and multiple surfaces with low vertical distance might cause bad results.";
+    def->cli = "match-horizontal-surfaces!";
+    def->default_value = new ConfigOptionBool(true);
+
     def = this->add("max_fan_speed", coInt);
     def->label = "Max";
     def->tooltip = "This setting represents the maximum speed of your fan.";
@@ -599,7 +605,7 @@ PrintConfigDef::PrintConfigDef()
 	def->tooltip = "This is the highest printable layer height for this extruder and limits the resolution for adaptive slicing. Typical values are slightly smaller than nozzle_diameter.";
 	def->sidetext = "mm";
 	def->cli = "max-layer-height=f@";
-	//def->min = 0;
+	def->min = 0;
 	{
 		ConfigOptionFloats* opt = new ConfigOptionFloats();
 		opt->values.push_back(0.3);
@@ -636,7 +642,7 @@ PrintConfigDef::PrintConfigDef()
 	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.";
 	def->sidetext = "mm";
 	def->cli = "min-layer-height=f@";
-	//def->min = 0;
+	def->min = 0;
 	{
 		ConfigOptionFloats* opt = new ConfigOptionFloats();
 		opt->values.push_back(0.15);

xs/src/libslic3r/PrintConfig.hpp

@@ -110,6 +110,7 @@ class PrintObjectConfig : public virtual StaticPrintConfig
     ConfigOptionBool                infill_only_where_needed;
     ConfigOptionBool                interface_shells;
     ConfigOptionFloat               layer_height;
+    ConfigOptionBool                match_horizontal_surfaces;
     ConfigOptionInt                 raft_layers;
     ConfigOptionEnum<SeamPosition>  seam_position;
     ConfigOptionBool                support_material;
@@ -141,6 +142,7 @@ class PrintObjectConfig : public virtual StaticPrintConfig
         OPT_PTR(infill_only_where_needed);
         OPT_PTR(interface_shells);
         OPT_PTR(layer_height);
+        OPT_PTR(match_horizontal_surfaces);
         OPT_PTR(raft_layers);
         OPT_PTR(seam_position);
         OPT_PTR(support_material);

xs/src/libslic3r/PrintObject.cpp

@@ -229,6 +229,7 @@ PrintObject::invalidate_state_by_config_options(const std::vector<t_config_optio
             || *opt_key == "xy_size_compensation"
             || *opt_key == "adaptive_slicing"
         	|| *opt_key == "cusp_value"
+        	|| *opt_key == "match_horizontal_surfaces"
         	|| *opt_key == "raft_layers") {
             steps.insert(posSlice);
         } else if (*opt_key == "support_material"