When the support extruders are set to 0, support is printed with the current material without a tool change.

A fix of support path generator.

lib/Slic3r/Print/GCode.pm

@@ -480,7 +480,9 @@ sub process_layer {
         # and also because we avoid travelling on other things when printing it
         if ($layer->isa('Slic3r::Layer::Support')) {
             if ($layer->support_interface_fills->count > 0) {
-                $gcode .= $self->_gcodegen->set_extruder($object->config->support_material_interface_extruder-1);
+                # Don't change extruder if the extruder is set to 0. Use the current extruder instead.
+                $gcode .= $self->_gcodegen->set_extruder($object->config->support_material_interface_extruder-1)
+                    if ($object->config->support_material_interface_extruder > 0);
                 for my $path (@{$layer->support_interface_fills->chained_path_from($self->_gcodegen->last_pos, 0)}) {
                     if ($path->isa('Slic3r::ExtrusionMultiPath')) {
                         $gcode .= $self->_gcodegen->extrude_multipath($path, 'support material interface', $object->config->get_abs_value('support_material_interface_speed'));
@@ -490,7 +492,9 @@ sub process_layer {
                 }
             }
             if ($layer->support_fills->count > 0) {
-                $gcode .= $self->_gcodegen->set_extruder($object->config->support_material_extruder-1);
+                # Don't change extruder if the extruder is set to 0. Use the current extruder instead.
+                $gcode .= $self->_gcodegen->set_extruder($object->config->support_material_extruder-1)
+                    if ($object->config->support_material_extruder > 0);
                 for my $path (@{$layer->support_fills->chained_path_from($self->_gcodegen->last_pos, 0)}) {
                     if ($path->isa('Slic3r::ExtrusionMultiPath')) {
                         $gcode .= $self->_gcodegen->extrude_multipath($path, 'support material', $object->config->get_abs_value('support_material_speed'));

lib/Slic3r/Print/Object.pm

@@ -150,6 +150,7 @@ sub prepare_infill {
     # Decide what surfaces are to be filled.
     # Here the S_TYPE_TOP / S_TYPE_BOTTOMBRIDGE / S_TYPE_BOTTOM infill is turned to just S_TYPE_INTERNAL if zero top / bottom infill layers are configured.
     # Also tiny S_TYPE_INTERNAL surfaces are turned to S_TYPE_INTERNAL_SOLID.
+#    BOOST_LOG_TRIVIAL(info) << "Preparing fill surfaces...";
     $_->prepare_fill_surfaces for map @{$_->regions}, @{$self->layers};
 
     # this will detect bridges and reverse bridges
@@ -262,28 +263,8 @@ sub generate_support_material {
     
     if (($self->config->support_material || $self->config->raft_layers > 0) && scalar(@{$self->layers}) > 1) {
         $self->print->status_cb->(85, "Generating support material");    
-        if (0) {
+        # New supports, C++ implementation.
-            # Old supports, Perl implementation.
+        $self->_generate_support_material;
-            my $first_layer_flow = Slic3r::Flow->new_from_width(
-                width               => ($self->print->config->first_layer_extrusion_width || $self->config->support_material_extrusion_width),
-                role                => FLOW_ROLE_SUPPORT_MATERIAL,
-                nozzle_diameter     => $self->print->config->nozzle_diameter->[ $self->config->support_material_extruder-1 ]
-                                        // $self->print->config->nozzle_diameter->[0],
-                layer_height        => $self->config->get_abs_value('first_layer_height'),
-                bridge_flow_ratio   => 0,
-            );            
-            my $support_material = Slic3r::Print::SupportMaterial->new(
-                print_config        => $self->print->config,
-                object_config       => $self->config,
-                first_layer_flow    => $first_layer_flow,
-                flow                => $self->support_material_flow,
-                interface_flow      => $self->support_material_flow(FLOW_ROLE_SUPPORT_MATERIAL_INTERFACE),
-            );
-            $support_material->generate($self);
-        } else {
-            # New supports, C++ implementation.
-            $self->_generate_support_material;
-        }
     }
     
     $self->set_step_done(STEP_SUPPORTMATERIAL);
@@ -727,6 +708,8 @@ sub _simplify_slices {
     }
 }
 
+# Used by t/support.t and by GCode.pm to export support line width as a comment.
+# To be removed.
 sub support_material_flow {
     my ($self, $role) = @_;
     

slic3r.pl

@@ -540,9 +540,11 @@ $j
     --infill-extruder   Extruder to use for infill (1+, default: $config->{infill_extruder})
     --solid-infill-extruder   Extruder to use for solid infill (1+, default: $config->{solid_infill_extruder})
     --support-material-extruder
-                        Extruder to use for support material, raft and skirt (1+, default: $config->{support_material_extruder})
+                        Extruder to use for support material, raft and skirt 
+                        (1+, 0 to use the current extruder to minimize tool changes, default: $config->{support_material_extruder})
     --support-material-interface-extruder
-                        Extruder to use for support material interface (1+, default: $config->{support_material_interface_extruder})
+                        Extruder to use for support material interface 
+                        (1+, 0 to use the current extruder to minimize tool changes, default: $config->{support_material_interface_extruder})
     --ooze-prevention   Drop temperature and park extruders outside a full skirt for automatic wiping
                         (default: no)
     --standby-temperature-delta

xs/src/libslic3r/Print.cpp

@@ -323,13 +323,26 @@ std::set<size_t>
 Print::support_material_extruders() const
 {
     std::set<size_t> extruders;
-    
+    bool support_uses_current_extruder = false;
+
     FOREACH_OBJECT(this, object) {
         if ((*object)->has_support_material()) {
-            extruders.insert((*object)->config.support_material_extruder - 1);
+            if ((*object)->config.support_material_extruder == 0)
-            extruders.insert((*object)->config.support_material_interface_extruder - 1);
+                support_uses_current_extruder = true;
+            else
+                extruders.insert((*object)->config.support_material_extruder - 1);
+            if ((*object)->config.support_material_interface_extruder == 0)
+                support_uses_current_extruder = true;
+            else
+                extruders.insert((*object)->config.support_material_interface_extruder - 1);
         }
     }
+
+    if (support_uses_current_extruder) {
+        // Add all object extruders to the support extruders as it is not know which one will be used to print supports.
+        std::set<size_t> object_extruders = this->object_extruders();
+        extruders.insert(object_extruders.begin(), object_extruders.end());
+    }
     
     return extruders;
 }
@@ -653,6 +666,17 @@ Print::validate() const
         
         FOREACH_OBJECT(this, i_object) {
             PrintObject* object = *i_object;
+
+            if ((object->config.support_material_extruder == -1 || object->config.support_material_interface_extruder == -1) &&
+                (object->config.raft_layers > 0 || object->config.support_material.value)) {
+                // The object has some form of support and either support_material_extruder or support_material_interface_extruder
+                // will be printed with the current tool without a forced tool change. Play safe, assert that all object nozzles
+                // are of the same diameter.
+                if (nozzle_diameters.size() > 1)
+                    return "Printing with multiple extruders of differing nozzle diameters. "
+                           "If support is to be printed with the current extruder (support_material_extruder == 0 or support_material_interface_extruder == 0), ", 
+                           "all nozzles have to be of the same diameter.";
+            }
             
             // validate first_layer_height
             double first_layer_height = object->config.get_abs_value("first_layer_height");
@@ -662,7 +686,9 @@ Print::validate() const
                 size_t first_layer_extruder = object->config.raft_layers == 1
                     ? object->config.support_material_interface_extruder-1
                     : object->config.support_material_extruder-1;
-                first_layer_min_nozzle_diameter = this->config.nozzle_diameter.get_at(first_layer_extruder);
+                first_layer_min_nozzle_diameter = (first_layer_extruder == size_t(-1)) ? 
+                    min_nozzle_diameter : 
+                    this->config.nozzle_diameter.get_at(first_layer_extruder);
             } else {
                 // if we don't have raft layers, any nozzle diameter is potentially used in first layer
                 first_layer_min_nozzle_diameter = min_nozzle_diameter;

xs/src/libslic3r/PrintConfig.cpp

@@ -1176,9 +1176,9 @@ PrintConfigDef::PrintConfigDef()
     def = this->add("support_material_extruder", coInt);
     def->label = "Support material/raft/skirt extruder";
     def->category = "Extruders";
-    def->tooltip = "The extruder to use when printing support material, raft and skirt.";
+    def->tooltip = "The extruder to use when printing support material, raft and skirt (1+, 0 to use the current extruder to minimize tool changes).";
     def->cli = "support-material-extruder=i";
-    def->min = 1;
+    def->min = 0;
     def->default_value = new ConfigOptionInt(1);
 
     def = this->add("support_material_extrusion_width", coFloatOrPercent);
@@ -1199,9 +1199,9 @@ PrintConfigDef::PrintConfigDef()
     def = this->add("support_material_interface_extruder", coInt);
     def->label = "Support material/raft interface extruder";
     def->category = "Extruders";
-    def->tooltip = "The extruder to use when printing support material interface. This affects raft too.";
+    def->tooltip = "The extruder to use when printing support material interface (1+, 0 to use the current extruder to minimize tool changes). This affects raft too.";
     def->cli = "support-material-interface-extruder=i";
-    def->min = 1;
+    def->min = 0;
     def->default_value = new ConfigOptionInt(1);
 
     def = this->add("support_material_interface_layers", coInt);

xs/src/libslic3r/Slicing.cpp

@@ -27,6 +27,11 @@ SlicingParameters SlicingParameters::create_from_config(
     coordf_t first_layer_height                      = (object_config.first_layer_height.value <= 0) ? 
         object_config.layer_height.value : 
         object_config.first_layer_height.get_abs_value(object_config.layer_height.value);
+    // If object_config.support_material_extruder == 0 resp. object_config.support_material_interface_extruder == 0,
+    // print_config.nozzle_diameter.get_at(size_t(-1)) returns the 0th nozzle diameter,
+    // which is consistent with the requirement that if support_material_extruder == 0 resp. support_material_interface_extruder == 0,
+    // support will not trigger tool change, but it will use the current nozzle instead.
+    // In that case all the nozzles have to be of the same diameter.
     coordf_t support_material_extruder_dmr           = print_config.nozzle_diameter.get_at(object_config.support_material_extruder.value - 1);
     coordf_t support_material_interface_extruder_dmr = print_config.nozzle_diameter.get_at(object_config.support_material_interface_extruder.value - 1);
     bool     soluble_interface                       = object_config.support_material_contact_distance.value == 0.;

xs/src/libslic3r/SupportMaterial.cpp

@@ -150,6 +150,7 @@ PrintObjectSupportMaterial::PrintObjectSupportMaterial(const PrintObject *object
         frSupportMaterial, 
         // The width parameter accepted by new_from_config_width is of type ConfigOptionFloatOrPercent, the Flow class takes care of the percent to value substitution.
         (object->config.support_material_extrusion_width.value > 0) ? object->config.support_material_extrusion_width : object->config.extrusion_width,
+        // if object->config.support_material_extruder == 0 (which means to not trigger tool change, but use the current extruder instead), get_at will return the 0th component.
         float(object->print()->config.nozzle_diameter.get_at(object->config.support_material_extruder-1)),
         float(slicing_params.layer_height),
         false)), 
@@ -157,6 +158,7 @@ PrintObjectSupportMaterial::PrintObjectSupportMaterial(const PrintObject *object
         frSupportMaterialInterface,
         // The width parameter accepted by new_from_config_width is of type ConfigOptionFloatOrPercent, the Flow class takes care of the percent to value substitution.
         (object->config.support_material_extrusion_width > 0) ? object->config.support_material_extrusion_width : object->config.extrusion_width,
+        // if object->config.support_material_interface_extruder == 0 (which means to not trigger tool change, but use the current extruder instead), get_at will return the 0th component.
         float(object->print()->config.nozzle_diameter.get_at(object->config.support_material_interface_extruder-1)),
         float(slicing_params.layer_height),
         false)),
@@ -636,7 +638,7 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::top_contact_
 
                 #ifdef SLIC3R_DEBUG
                 Slic3r::SVG::export_expolygons(
-                    debug_out_path("support-top-contacts-filtered-run%d-layer%d-region%d.svg", iRun, layer_id, it_layerm - layer.regions.begin()),
+                    debug_out_path("support-top-contacts-filtered-run%d-layer%d-region%d-z%f.svg", iRun, layer_id, it_layerm - layer.regions.begin(), layer.print_z),
                     union_ex(diff_polygons, false));
                 #endif /* SLIC3R_DEBUG */
 
@@ -758,7 +760,7 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::top_contact_
                 bbox.align_to_grid(grid_resolution);
                 grid.set_bbox(bbox);
                 grid.create(contact_polygons, grid_resolution);
-                grid.calculate_sdf();
+                grid.calculate_sdf();                
                 // Extract a bounding contour from the grid, trim by the object.
                 // 1) infill polygons, expand them by half the extrusion width + a tiny bit of extra.
                 new_layer.polygons = diff(
@@ -772,6 +774,9 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::top_contact_
                     false));
             }
 #endif
+            // Even after the contact layer was expanded into a grid, some of the contact islands may be too tiny to be extruded.
+            // Remove those tiny islands from new_layer.polygons and new_layer.contact_polygons.
+            
 
             // Store the overhang polygons.
             // The overhang polygons are used in the path generator for planning of the contact loops.
@@ -2182,33 +2187,20 @@ void PrintObjectSupportMaterial::generate_toolpaths(
         MyLayerExtruded top_contact_layer;
         MyLayerExtruded base_layer;
         MyLayerExtruded interface_layer;
-        MyLayerExtrudedPtrs mylayers;
-
         // Increment the layer indices to find a layer at support_layer.print_z.
         for (; idx_layer_bottom_contact < bottom_contacts    .size() && bottom_contacts    [idx_layer_bottom_contact]->print_z < support_layer.print_z - EPSILON; ++ idx_layer_bottom_contact) ;
         for (; idx_layer_top_contact    < top_contacts       .size() && top_contacts       [idx_layer_top_contact   ]->print_z < support_layer.print_z - EPSILON; ++ idx_layer_top_contact   ) ;
         for (; idx_layer_intermediate   < intermediate_layers.size() && intermediate_layers[idx_layer_intermediate  ]->print_z < support_layer.print_z - EPSILON; ++ idx_layer_intermediate  ) ;
         for (; idx_layer_inteface       < interface_layers   .size() && interface_layers   [idx_layer_inteface      ]->print_z < support_layer.print_z - EPSILON; ++ idx_layer_inteface      ) ;
         // Copy polygons from the layers.
-        mylayers.reserve(4);
+        if (idx_layer_bottom_contact < bottom_contacts.size() && bottom_contacts[idx_layer_bottom_contact]->print_z < support_layer.print_z + EPSILON)
-        if (idx_layer_bottom_contact < bottom_contacts.size() && bottom_contacts[idx_layer_bottom_contact]->print_z < support_layer.print_z + EPSILON) {
             bottom_contact_layer.layer = bottom_contacts[idx_layer_bottom_contact];
-            mylayers.push_back(&bottom_contact_layer);
+        if (idx_layer_top_contact < top_contacts.size() && top_contacts[idx_layer_top_contact]->print_z < support_layer.print_z + EPSILON)
-        }
-        if (idx_layer_top_contact < top_contacts.size() && top_contacts[idx_layer_top_contact]->print_z < support_layer.print_z + EPSILON) {
             top_contact_layer.layer = top_contacts[idx_layer_top_contact];
-            mylayers.push_back(&top_contact_layer);
+        if (idx_layer_inteface < interface_layers.size() && interface_layers[idx_layer_inteface]->print_z < support_layer.print_z + EPSILON)
-        }
-        if (idx_layer_inteface < interface_layers.size() && interface_layers[idx_layer_inteface]->print_z < support_layer.print_z + EPSILON) {
             interface_layer.layer = interface_layers[idx_layer_inteface];
-            mylayers.push_back(&interface_layer);
+        if (idx_layer_intermediate < intermediate_layers.size() && intermediate_layers[idx_layer_intermediate]->print_z < support_layer.print_z + EPSILON)
-        }
-        if (idx_layer_intermediate < intermediate_layers.size() && intermediate_layers[idx_layer_intermediate]->print_z < support_layer.print_z + EPSILON) {
             base_layer.layer = intermediate_layers[idx_layer_intermediate];
-            mylayers.push_back(&base_layer);
-        }
-        // Sort the layers with the same print_z coordinate by their heights, thickest first.
-        std::sort(mylayers.begin(), mylayers.end(), [](const MyLayerExtruded *p1, const MyLayerExtruded *p2) { return p1->layer->height > p2->layer->height; });
 
         if (m_object_config->support_material_interface_layers == 0) {
             // If no interface layers were requested, we treat the contact layer exactly as a generic base layer.
@@ -2316,6 +2308,18 @@ void PrintObjectSupportMaterial::generate_toolpaths(
                 erSupportMaterial, flow);
         }
 
+        MyLayerExtrudedPtrs mylayers;
+        mylayers.reserve(4);
+        if (! bottom_contact_layer.empty())
+            mylayers.push_back(&bottom_contact_layer);
+        if (! top_contact_layer.empty())
+            mylayers.push_back(&top_contact_layer);
+        if (! interface_layer.empty())
+            mylayers.push_back(&interface_layer);
+        if (! base_layer.empty())
+            mylayers.push_back(&base_layer);
+        // Sort the layers with the same print_z coordinate by their heights, thickest first.
+        std::sort(mylayers.begin(), mylayers.end(), [](const MyLayerExtruded *p1, const MyLayerExtruded *p2) { return p1->layer->height > p2->layer->height; });
         // Collect the support areas with this print_z into islands, as there is no need
         // for retraction over these islands.
         Polygons polys;