Force the 'nearest' strategy for starting skirt loops

lib/Slic3r/ExtrusionLoop.pm

@@ -5,7 +5,7 @@ use warnings;
 use parent qw(Exporter);
 
 our @EXPORT_OK = qw(EXTRL_ROLE_DEFAULT
-    EXTRL_ROLE_CONTOUR_INTERNAL_PERIMETER);
+    EXTRL_ROLE_CONTOUR_INTERNAL_PERIMETER EXTRL_ROLE_SKIRT);
 our %EXPORT_TAGS = (roles => \@EXPORT_OK);
 
 

lib/Slic3r/Print.pm

@@ -5,6 +5,7 @@ use warnings;
 use File::Basename qw(basename fileparse);
 use File::Spec;
 use List::Util qw(min max first sum);
+use Slic3r::ExtrusionLoop ':roles';
 use Slic3r::ExtrusionPath ':roles';
 use Slic3r::Flow ':roles';
 use Slic3r::Geometry qw(X Y Z X1 Y1 X2 Y2 MIN MAX PI scale unscale convex_hull);
@@ -273,7 +274,7 @@ sub make_skirt {
     for (my $i = $skirts; $i > 0; $i--) {
         $distance += scale $spacing;
         my $loop = offset([$convex_hull], $distance, 1, JT_ROUND, scale(0.1))->[0];
-        $self->skirt->append(Slic3r::ExtrusionLoop->new_from_paths(
+        my $eloop = Slic3r::ExtrusionLoop->new_from_paths(
             Slic3r::ExtrusionPath->new(
                 polyline        => Slic3r::Polygon->new(@$loop)->split_at_first_point,
                 role            => EXTR_ROLE_SKIRT,
@@ -281,7 +282,9 @@ sub make_skirt {
                 width           => $flow->width,
                 height          => $first_layer_height, # this will be overridden at G-code export time
             ),
-        ));
+        );
+        $eloop->role(EXTRL_ROLE_SKIRT);
+        $self->skirt->append($eloop);
         
         if ($self->config->min_skirt_length > 0) {
             $extruded_length[$extruder_idx] ||= 0;

xs/src/libslic3r/ExtrusionEntity.hpp

@@ -31,6 +31,7 @@ enum ExtrusionRole {
 enum ExtrusionLoopRole {
     elrDefault,
     elrContourInternalPerimeter,
+    elrSkirt,
 };
 
 class ExtrusionEntity

xs/src/libslic3r/GCode.cpp

@@ -316,12 +316,15 @@ GCode::extrude(ExtrusionLoop loop, std::string description, double speed)
     // extrude all loops ccw
     bool was_clockwise = loop.make_counter_clockwise();
     
+    SeamPosition seam_position = this->config.seam_position;
+    if (loop.role == elrSkirt) seam_position = spNearest;
+    
     // find the point of the loop that is closest to the current extruder position
     // or randomize if requested
     Point last_pos = this->last_pos();
     if (this->config.spiral_vase) {
         loop.split_at(last_pos);
-    } else if (this->config.seam_position == spNearest || this->config.seam_position == spAligned) {
+    } else if (seam_position == spNearest || seam_position == spAligned) {
         const Polygon polygon = loop.polygon();
         
         // simplify polygon in order to skip false positives in concave/convex detection
@@ -356,7 +359,7 @@ GCode::extrude(ExtrusionLoop loop, std::string description, double speed)
         }
         
         Point point;
-        if (this->config.seam_position == spNearest) {
+        if (seam_position == spNearest) {
             if (candidates.empty()) candidates = polygon.points;
             last_pos.nearest_point(candidates, &point);
             
@@ -382,7 +385,7 @@ GCode::extrude(ExtrusionLoop loop, std::string description, double speed)
         }
         if (this->layer != NULL)
             this->_seam_position[this->layer->object()] = point;
-    } else if (this->config.seam_position == spRandom) {
+    } else if (seam_position == spRandom) {
         if (loop.role == elrContourInternalPerimeter) {
             Polygon polygon = loop.polygon();
             Point centroid = polygon.centroid();

xs/xsp/ExtrusionLoop.xsp

@@ -66,6 +66,7 @@ _constant()
   ALIAS:
     EXTRL_ROLE_DEFAULT                      = elrDefault
     EXTRL_ROLE_CONTOUR_INTERNAL_PERIMETER   = elrContourInternalPerimeter
+    EXTRL_ROLE_SKIRT                        = elrSkirt
   PROTOTYPE:
   CODE:
     RETVAL = ix;