Implemented retraction and fixed extrusion math

README.markdown

@@ -33,6 +33,7 @@ Slic3r is able to:
 * read binary and ASCII STL files;
 * generate multiple perimeters (skins);
 * generate rectilinear fill (100% solid for external surfaces or with customizable less density for inner surfaces);
+* retraction;
 * use relative or absolute extrusion commands;
 * center print around bed center point;
 * use different speed for bottom layer;
@@ -42,10 +43,10 @@ Roadmap includes the following goals:
 
 * output some statistics;
 * allow the user to customize initial and final GCODE commands;
-* retraction;
 * option for filling multiple solid layers near external surfaces;
 * support material for internal perimeters;
 * ability to infill in the direction of bridges;
+* extra perimeters on alternate layers;
 * skirt;
 * cool;
 * nice packaging for cross-platform deployment.

lib/Slic3r.pm

@@ -24,15 +24,20 @@ use Slic3r::Surface;
 our $layer_height       = 0.4;
 our $resolution         = 0.1;
 our $perimeter_offsets  = 3;
-our $fill_density       = 0.2;  # 1 = 100%
+our $fill_density       = 0.4;  # 1 = 100%
-our $flow_width         = 0.4;
+our $filament_diameter  = 3;    # mm
+our $filament_packing_density = 0.85;
+our $flow_width         = 0.50;
 our $temperature        = 195;
 
-our $flow_rate          = 60;   # mm/sec
 our $print_feed_rate    = 60;   # mm/sec
 our $travel_feed_rate   = 80;   # mm/sec
 our $bottom_layer_speed_ratio = 0.6;
 
+our $retract_length         = 2;    # mm
+our $retract_restart_extra  = 0;    # mm
+our $retract_speed          = 40;   # mm/sec
+
 our $use_relative_e_distances = 0;
 
 our $print_center       = [100,100];  # object will be centered around this point

lib/Slic3r/Fill/Rectilinear.pm

@@ -19,7 +19,7 @@ sub make_fill {
     # let's alternate fill direction
     my @axes = $layer->id % 2 == 0 ? (0,1) : (1,0);
     
-    foreach my $surface (@{ $layer->fill_surfaces }) {
+    SURFACE: foreach my $surface (@{ $layer->fill_surfaces }) {
         Slic3r::debugf " Processing surface %s:\n", $surface->id;
         my $polygon = $surface->mgp_polygon;
         
@@ -30,6 +30,7 @@ sub make_fill {
         
         # force 100% density for external surfaces
         my $density = $surface->surface_type eq 'internal' ? $Slic3r::fill_density : 1;
+        next SURFACE unless $density > 0;
         my $distance_between_lines = $Slic3r::flow_width / $Slic3r::resolution / $density;
         my $number_of_lines = ($axes[0] == 0 ? $print->x_length : $print->y_length) / $distance_between_lines;
         
@@ -96,7 +97,7 @@ sub make_fill {
         
             # loop through rows
             ROW: for (my $i = 0; $i < $number_of_lines; $i++) {
-                my $row = $points->[$i];
+                my $row = $points->[$i] or next ROW;
                 Slic3r::debugf "Processing row %d...\n", $i;
                 if (!@$row) {
                     Slic3r::debugf "  no points\n";

lib/Slic3r/Print.pm

@@ -1,6 +1,7 @@
 package Slic3r::Print;
 use Moose;
 
+use constant PI => 4 * atan2(1, 1);
 use constant X => 0;
 use constant Y => 1;
 
@@ -75,10 +76,10 @@ sub export_gcode {
     # calculate speed for gcode commands
     my $travel_feed_rate      = $Slic3r::travel_feed_rate * 60;  # mm/min
     my $print_feed_rate       = $Slic3r::print_feed_rate  * 60;  # mm/min
-    my $extrusion_speed_ratio = ($Slic3r::flow_rate / $Slic3r::print_feed_rate);
+    my $retract_speed         = $Slic3r::retract_speed    * 60;  # mm/min
     
     # calculate number of decimals
-    my $dec = length((1 / $Slic3r::resolution) - 1);
+    my $dec = length((1 / $Slic3r::resolution) - 1) + 1;
     
     # calculate X,Y shift to center print around specified origin
     my @shift = (
@@ -103,17 +104,33 @@ sub export_gcode {
     }
     
     # make up a subroutine to generate G1 commands
+    my $extrusion_distance = 0;
     my $G1 = sub {
-        my ($point, $z, $extrusion_distance, $comment) = @_;
+        my ($point, $z, $e, $comment) = @_;
-        printf $fh "G1 X%.${dec}f Y%.${dec}f Z%.${dec}f", 
+        printf $fh "G1";
+        
+        if ($point) {
+            printf $fh " X%.${dec}f Y%.${dec}f", 
                 ($point->x * $Slic3r::resolution) + $shift[X], 
-            ($point->y * $Slic3r::resolution) + $shift[Y], #**
+                ($point->y * $Slic3r::resolution) + $shift[Y]; #**
-            $z;
+        }
-        my $speed_multiplier = $z == 0 ? $Slic3r::bottom_layer_speed_ratio : 1;
+        if ($z) {
-        if ($extrusion_distance) {
+            printf $fh " Z%.${dec}f", $z;
-            printf $fh " F%.${dec}f E%.${dec}f", 
+        }
-                ($print_feed_rate * $speed_multiplier), 
+        
-                ($extrusion_distance * $extrusion_speed_ratio * $Slic3r::resolution);
+        # apply the speed reduction for print moves on bottom layer
+        my $speed_multiplier = defined $z && $z == 0 && $point 
+            ? $Slic3r::bottom_layer_speed_ratio 
+            : 1;
+
+        if ($e) {
+            $extrusion_distance = 0 if $Slic3r::use_relative_e_distances;
+            $extrusion_distance += $e;
+            printf $fh " F%.${dec}f E%.5f", 
+                $e < 0 
+                    ? $retract_speed
+                    : ($print_feed_rate * $speed_multiplier), 
+                $extrusion_distance;
         } else {
             printf $fh " F%.${dec}f", ($travel_feed_rate * $speed_multiplier);
         }
@@ -122,26 +139,41 @@ sub export_gcode {
     };
     
     my $z;
+    my $retracted = 0;
     my $Extrude = sub {
         my ($path, $description) = @_;
         
         # reset extrusion distance counter
-        my $extrusion_distance = 0;
         if (!$Slic3r::use_relative_e_distances) {
+            $extrusion_distance = 0;
             print $fh "G92 E0 ; reset extrusion distance\n";
         }
         
-        # go to first point (without extruding)
+        # go to first point while compensating retraction
-        $G1->($path->lines->[0]->a, $z, 0, "move to first $description point");
+        $G1->($path->lines->[0]->a, $z, 
+            $retracted 
+                ? ($Slic3r::retract_length + $Slic3r::retract_restart_extra)
+                : 0, 
+            "move to first $description point");
         
         # extrude while going to next points
         foreach my $line (@{ $path->lines }) {
-            $extrusion_distance = 0 if $Slic3r::use_relative_e_distances;
+            # calculate how much filament to drive into the extruder
-            $extrusion_distance += $line->a->distance_to($line->b);
+            # to get the desired amount of extruded plastic
-            $G1->($line->b, $z, $extrusion_distance, $description);
+            my $e = $line->a->distance_to($line->b) * $Slic3r::resolution
+                * $Slic3r::flow_width 
+                * $Slic3r::layer_height
+                / (($Slic3r::filament_diameter ** 2) * PI)
+                / $Slic3r::filament_packing_density;
+            
+            $G1->($line->b, $z, $e, $description);
         }
         
-        # TODO: retraction
+        # retract
+        if ($Slic3r::retract_length > 0) {
+            $G1->(undef, undef, -$Slic3r::retract_length, "retract");
+            $retracted = 1;
+        }
     };
     
     # write gcode commands layer by layer

slic3r.pl

@@ -10,6 +10,7 @@ BEGIN {
 
 use Getopt::Long;
 use Slic3r;
+use Time::HiRes qw(gettimeofday tv_interval);
 use XXX;
 
 my %opt;
@@ -23,15 +24,16 @@ GetOptions(
     'resolution=f'          => \$Slic3r::resolution,
     'perimeters=i'          => \$Slic3r::perimeter_offsets,
     'fill-density=f'        => \$Slic3r::fill_density,
+    'filament-diameter=f'   => \$Slic3r::filament_diameter,
     'flow-width=f'          => \$Slic3r::flow_width,
     'temperature=i'         => \$Slic3r::temperature,
-    'flow-rate=i'           => \$Slic3r::flow_rate,
     'print-feed-rate=i'     => \$Slic3r::print_feed_rate,
     'travel-feed-rate=i'    => \$Slic3r::travel_feed_rate,
     'bottom-layer-speed-ratio=f'    => \$Slic3r::bottom_layer_speed_ratio,
     'use-relative-e-distances'      => \$Slic3r::use_relative_e_distances,
     'print-center=s'        => \$Slic3r::print_center,
-    '',
+    'retract-length=f'      => \$Slic3r::retract_length,
+    'retract-restart-extra=f' => \$Slic3r::retract_restart_extra,
 );
 
 # validate configuration
@@ -42,6 +44,10 @@ GetOptions(
     die "--layer-height must be a multiple of print resolution\n"
         if $Slic3r::layer_height / $Slic3r::resolution % 1 != 0;
     
+    # --filament-diameter
+    die "Invalid value for --filament-diameter\n"
+        if $Slic3r::filament_diameter < 1;
+    
     # --flow-width
     die "Invalid value for --flow-width\n"
         if $Slic3r::flow_width < 0;
@@ -72,6 +78,7 @@ if ($action eq 'skein') {
     die "Input file must have .stl extension\n" 
         if $input_file !~ /\.stl$/i;
     
+    my $t0 = [gettimeofday];
     my $print = $stl_parser->parse_file($input_file);
     $print->extrude_perimeters;
     $print->extrude_fills;
@@ -79,6 +86,10 @@ if ($action eq 'skein') {
     my $output_file = $input_file;
     $output_file =~ s/\.stl$/.gcode/i;
     $print->export_gcode($opt{output} || $output_file);
+    
+    my $processing_time = tv_interval($t0);
+    printf "Done. Process took %d minutes and %.3f seconds\n", 
+        int($processing_time/60), $processing_time - int($processing_time/60);
 }
 
 sub usage {
@@ -93,14 +104,22 @@ Usage: slic3r.pl [ OPTIONS ] file.stl
     --perimeters        Number of perimeters/horizontal skins 
                         (range: 1+, default: $Slic3r::perimeter_offsets)
     --fill-density      Infill density (range: 0-1, default: $Slic3r::fill_density)
+    --filament-diameter Diameter of your raw filament (default: $Slic3r::filament_diameter)
+    --filament-packing-density
+                        Ratio of the extruded volume over volume pushed into 
+                        the extruder (default: $Slic3r::filament_packing_density)
     --flow-width        Width of extruded flow in mm (default: $Slic3r::flow_width)
-    --flow-rate         Speed of extrusion in mm/sec; should be equal to 
-                        --print-feed-rate (default: $Slic3r::flow_rate)
     --print-feed-rate   Speed of print moves in mm/sec (default: $Slic3r::print_feed_rate)
     --travel-feed-rate  Speed of non-print moves in mm/sec (default: $Slic3r::travel_feed_rate)
     --bottom-layer-speed-ratio
                         Factor to increase/decrease speeds on bottom layer by 
                         (default: $Slic3r::bottom_layer_speed_ratio)
+    --retract-length    Length of retraction in mm when pausing extrusion 
+                        (default: $Slic3r::retract_length)
+    --retract-speed     Speed for retraction in mm/sec (default: $Slic3r::retract_speed)
+    --retract-restart-extra
+                        Additional amount of filament in mm to push after compensating
+                        retraction (default: $Slic3r::retract_restart_extra)
     --use-relative-e-distances
                         Use relative distances for extrusion in GCODE output
     --print-center      Coordinates of the point to center the print around