From 50526dea5addba9b6193678a1cc404f4e5947796 Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Sun, 27 Jan 2013 13:06:45 +0100
Subject: [PATCH] Fix last_pos shifting and add unit test

---
 MANIFEST            |  1 +
 lib/Slic3r/GCode.pm |  5 +++--
 t/gcode.t           | 20 ++++++++++++++++++++
 3 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 t/gcode.t

diff --git a/MANIFEST b/MANIFEST
index 45612a57b..4f6b6fba3 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -58,6 +58,7 @@ t/collinear.t
 t/custom_gcode.t
 t/dynamic.t
 t/fill.t
+t/gcode.t
 t/geometry.t
 t/layers.t
 t/loops.t
diff --git a/lib/Slic3r/GCode.pm b/lib/Slic3r/GCode.pm
index bad4db918..30e54f734 100644
--- a/lib/Slic3r/GCode.pm
+++ b/lib/Slic3r/GCode.pm
@@ -57,9 +57,10 @@ sub set_shift {
     my $self = shift;
     my @shift = @_;
     
+    # if shift increases (goes towards right), last_pos decreases because it goes towards left
     $self->last_pos->translate(
-        scale ($shift[X] - $self->shift_x),
-        scale ($shift[Y] - $self->shift_y),
+        scale ($self->shift_x - $shift[X]),
+        scale ($self->shift_x - $shift[Y]),
     );
     
     $self->shift_x($shift[X]);
diff --git a/t/gcode.t b/t/gcode.t
new file mode 100644
index 000000000..c41307d4f
--- /dev/null
+++ b/t/gcode.t
@@ -0,0 +1,20 @@
+use Test::More tests => 1;
+use strict;
+use warnings;
+
+BEGIN {
+    use FindBin;
+    use lib "$FindBin::Bin/../lib";
+}
+
+use Slic3r;
+use Slic3r::Geometry qw(scale);
+
+{
+    local $Slic3r::Config = Slic3r::Config->new_from_defaults;
+    my $gcodegen = Slic3r::GCode->new(layer_count => 1);
+    $gcodegen->set_shift(10, 10);
+    is_deeply $gcodegen->last_pos, [scale -10, scale -10], 'last_pos is shifted correctly';
+}
+
+__END__