From 68b48fa807de50d6d05078e411b3b5fb3e51a3e4 Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Mon, 9 Apr 2012 12:29:47 +0200
Subject: [PATCH] Multithreaded mesh processing. #154

---
 lib/Slic3r.pm              | 17 +++++++++++++++++
 lib/Slic3r/Print.pm        | 35 ++++++++++++++++++++++++++++++++++-
 lib/Slic3r/TriangleMesh.pm |  5 ++++-
 3 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/lib/Slic3r.pm b/lib/Slic3r.pm
index 5c5e3b06..7a372acc 100644
--- a/lib/Slic3r.pm
+++ b/lib/Slic3r.pm
@@ -14,6 +14,7 @@ sub debugf {
     printf @_ if $debug;
 }
 
+use Config;
 use Slic3r::Config;
 use Slic3r::ExPolygon;
 use Slic3r::Extruder;
@@ -141,4 +142,20 @@ our $duplicate_x        = 1;
 our $duplicate_y        = 1;
 our $duplicate_distance = 6;    # mm
 
+sub parallelize {
+    my %params = @_;
+    
+    if (!$params{disable} && $Config{useithreads} && $Slic3r::threads > 1 && eval "use threads; use Thread::Queue; 1") {
+        my $q = Thread::Queue->new;
+        $q->enqueue(@{ $params{items} }, (map undef, 1..$Slic3r::threads));
+        
+        my $thread_cb = sub { $params{thread_cb}->($q) };
+        foreach my $th (map threads->create($thread_cb), 1..$Slic3r::threads) {
+            $params{collect_cb}->($th->join);
+        }
+    } else {
+        $params{no_threads_cb}->();
+    }
+}
+
 1;
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 3495b980..2790b0b4 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -39,7 +39,40 @@ sub new_from_mesh {
     );
     
     # process facets
-    $mesh->slice_facet($print, $_) for 0..$#{$mesh->facets};
+    {
+        my $apply_lines = sub {
+            my $lines = shift;
+            foreach my $layer_id (keys %$lines) {
+                my $layer = $print->layer($layer_id);
+                $layer->add_line($_) for @{ $lines->{$layer_id} };
+            }
+        };
+        Slic3r::parallelize(
+            disable => ($#{$mesh->facets} < 500),  # don't parallelize when too few facets
+            items => [ 0..$#{$mesh->facets} ],
+            thread_cb => sub {
+                my $q = shift;
+                my $result_lines = {};
+                while (defined (my $facet_id = $q->dequeue)) {
+                    my $lines = $mesh->slice_facet($print, $facet_id);
+                    foreach my $layer_id (keys %$lines) {
+                        $result_lines->{$layer_id} ||= [];
+                        push @{ $result_lines->{$layer_id} }, @{ $lines->{$layer_id} };
+                    }
+                }
+                return $result_lines;
+            },
+            collect_cb => sub {
+                $apply_lines->($_[0]);
+            },
+            no_threads_cb => sub {
+                for (0..$#{$mesh->facets}) {
+                    my $lines = $mesh->slice_facet($print, $_);
+                    $apply_lines->($lines);
+                }
+            },
+        );
+    }
     die "Invalid input file\n" if !@{$print->layers};
     
     # remove last layer if empty
diff --git a/lib/Slic3r/TriangleMesh.pm b/lib/Slic3r/TriangleMesh.pm
index 6e0aca0b..32f02cf5 100644
--- a/lib/Slic3r/TriangleMesh.pm
+++ b/lib/Slic3r/TriangleMesh.pm
@@ -366,10 +366,13 @@ sub slice_facet {
     my $max_layer = int((unscale($max_z) - ($first_layer_height + $Slic3r::layer_height / 2)) / $Slic3r::layer_height) + 2;
     Slic3r::debugf "layers: min = %s, max = %s\n", $min_layer, $max_layer;
     
+    my $lines = {};  # layer_id => [ lines ]
     for (my $layer_id = $min_layer; $layer_id <= $max_layer; $layer_id++) {
         my $layer = $print->layer($layer_id);
-        $layer->add_line($_) for $self->intersect_facet($facet_id, $layer->slice_z);
+        $lines->{$layer_id} ||= [];
+        push @{ $lines->{$layer_id} }, $self->intersect_facet($facet_id, $layer->slice_z);
     }
+    return $lines;
 }
 
 sub intersect_facet {