From b73c301c5582af7945e656978a946c39f5b64d5e Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Mon, 11 Mar 2013 17:06:05 +0100
Subject: [PATCH] Bugfix: double lift at toolchange. #953

---
 lib/Slic3r/GCode.pm | 16 +++++++++-------
 t/retraction.t      |  1 +
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/lib/Slic3r/GCode.pm b/lib/Slic3r/GCode.pm
index 1cb2783a7..c3501d437 100644
--- a/lib/Slic3r/GCode.pm
+++ b/lib/Slic3r/GCode.pm
@@ -350,7 +350,7 @@ sub retract {
     # prepare moves
     $self->speed('retract');
     my $retract = [undef, undef, -$length, $comment];
-    my $lift    = ($self->extruder->retract_lift == 0 || defined $params{move_z})
+    my $lift    = ($self->extruder->retract_lift == 0 || defined $params{move_z}) && !$self->lifted
         ? undef
         : [undef, $self->z + $self->extruder->retract_lift, 0, 'lift plate during travel'];
     
@@ -371,12 +371,14 @@ sub retract {
         $gcode .= $self->G0(@$travel);
     } else {
         $gcode .= $self->G1(@$retract);
-        if (defined $params{move_z} && $self->extruder->retract_lift > 0) {
-            my $travel = [undef, $params{move_z} + $self->extruder->retract_lift, 0, 'move to next layer (' . $self->layer->id . ') and lift'];
-            $gcode .= $self->G0(@$travel);
-            $self->lifted($self->extruder->retract_lift);
-        } elsif ($lift) {
-            $gcode .= $self->G1(@$lift);
+        if (!$self->lifted) {
+            if (defined $params{move_z} && $self->extruder->retract_lift > 0) {
+                my $travel = [undef, $params{move_z} + $self->extruder->retract_lift, 0, 'move to next layer (' . $self->layer->id . ') and lift'];
+                $gcode .= $self->G0(@$travel);
+                $self->lifted($self->extruder->retract_lift);
+            } elsif ($lift) {
+                $gcode .= $self->G1(@$lift);
+            }
         }
     }
     $self->extruder->retracted($self->extruder->retracted + $length);
diff --git a/t/retraction.t b/t/retraction.t
index 3b90dfda7..f89700e94 100644
--- a/t/retraction.t
+++ b/t/retraction.t
@@ -43,6 +43,7 @@ my $test = sub {
             if (_eq($info->{dist_Z}, $print->extruders->[$tool]->retract_lift)
                 || (_eq($info->{dist_Z}, $conf->layer_height + $print->extruders->[$tool]->retract_lift) && $print->extruders->[$tool]->retract_lift > 0)) {
                 fail 'only lifting while retracted' if !$retracted[$tool] && !($conf->g0 && $info->{retracting});
+                fail 'double lift' if $lifted;
                 $lifted = 1;
             }
             if ($info->{dist_Z} < 0) {