From 00e8ba478176103271ad31bcf867ba0c4444b244 Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Sat, 7 Dec 2013 14:52:59 +0100
Subject: [PATCH] Fix regression causing complete_objects to skip Z moves after
 first object is complete. Includes regression test. #1582 #1541

---
 lib/Slic3r/GCode.pm | 32 ++++++++++++++++++++------------
 t/gcode.t           | 16 +++++++++++++++-
 2 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/lib/Slic3r/GCode.pm b/lib/Slic3r/GCode.pm
index c89d98c82..26a9ba76f 100644
--- a/lib/Slic3r/GCode.pm
+++ b/lib/Slic3r/GCode.pm
@@ -130,25 +130,33 @@ sub change_layer {
 sub move_z {
     my ($self, $z, $comment) = @_;
     
-    $z += $self->config->z_offset;
-    
     my $gcode = "";
+    
+    $z += $self->config->z_offset;
     my $current_z = $self->z;
-    if (!defined $self->z || $z > $self->z) {
-        # if we're going over the current Z we won't be lifted anymore
+    my $nominal_z = defined $current_z ? ($current_z - $self->lifted) : undef;
+    
+    if (!defined $current_z || $z > $current_z || $z < $nominal_z) {
+        # we're moving above the current actual Z (so above the lift height of the current
+        # layer if any) or below the current nominal layer
+        
+        # in both cases, we're going to the nominal Z of the next layer
         $self->lifted(0);
         
-        # this retraction may alter $self->z
-        $gcode .= $self->retract(move_z => $z) if $self->extruder->retract_layer_change;
+        if ($self->extruder->retract_layer_change) {
+            # this retraction may alter $self->z
+            $gcode .= $self->retract(move_z => $z);
+            $current_z = $self->z;  # update current z in case retract() changed it
+            $nominal_z = defined $current_z ? ($current_z - $self->lifted) : undef;
+        }
         $self->speed('travel');
         $gcode .= $self->G0(undef, $z, 0, $comment || ('move to next layer (' . $self->layer->id . ')'))
-            if !defined $self->z || abs($z - ($self->z - $self->lifted)) > epsilon;
-    } elsif ($z < $self->z && $z > ($self->z - $self->lifted + epsilon)) {
-        # we're moving to a layer height which is greater than the nominal current one
-        # (nominal = actual - lifted) and less than the actual one.  we're basically
-        # advancing to next layer, whose nominal Z is still lower than the previous
+            if !defined $current_z || abs($z - $nominal_z) > epsilon;
+    } elsif ($z < $current_z) {
+        # we're moving above the current nominal layer height and below the current actual one.
+        # we're basically advancing to next layer, whose nominal Z is still lower than the previous
         # layer Z with lift.
-        $self->lifted($self->z - $z);
+        $self->lifted($current_z - $z);
     }
     
     return $gcode;
diff --git a/t/gcode.t b/t/gcode.t
index f8ee4158c..17f4ed824 100644
--- a/t/gcode.t
+++ b/t/gcode.t
@@ -1,4 +1,4 @@
-use Test::More tests => 4;
+use Test::More tests => 6;
 use strict;
 use warnings;
 
@@ -43,16 +43,30 @@ use Slic3r::Test;
 }
 
 {
+    # This tests the following behavior:
+    # - complete objects does not crash
+    # - no hard-coded "E" are generated
+    # - Z moves are correctly generated for both objects
     my $config = Slic3r::Config->new_from_defaults;
     $config->set('complete_objects', 1);
     $config->set('duplicate', 2);
     $config->set('extrusion_axis', 'A');
+    $config->set('start_gcode', '');  # prevent any default extra Z move
+    $config->set('layer_height', 0.4);
+    $config->set('first_layer_height', 0.4);
     my $print = Slic3r::Test::init_print('20mm_cube', config => $config);
     ok my $gcode = Slic3r::Test::gcode($print), "complete_objects";
+    my @z_moves = ();
     Slic3r::GCode::Reader->new->parse($gcode, sub {
         my ($self, $cmd, $args, $info) = @_;
         fail 'unexpected E argument' if defined $args->{E};
+        if (defined $args->{Z}) {
+            push @z_moves, $args->{Z};
+        }
     });
+    my $layer_count = 20/0.4;  # cube is 20mm tall
+    is scalar(@z_moves), 2*$layer_count, 'complete_objects generates the correct number of Z moves';
+    is_deeply [ @z_moves[0..($layer_count-1)] ], [ @z_moves[$layer_count..$#z_moves] ], 'complete_objects generates the correct Z moves';
 }
 
 __END__