From 28695c719c80c2c3bc78f88d240bc3bce37749bd Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Tue, 3 Jun 2014 23:59:03 +0200
Subject: [PATCH] Fixed regression causing bridge flow to be incorrect when a
 manual default extrusion width was specified. Includes several regression
 tests. #2027

---
 t/flow.t        | 42 ++++++++++++++++++++++++++++++++++++++++--
 xs/src/Flow.cpp |  3 ++-
 2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/t/flow.t b/t/flow.t
index 0d436f5a..80fc12c5 100644
--- a/t/flow.t
+++ b/t/flow.t
@@ -1,4 +1,4 @@
-use Test::More tests => 1;
+use Test::More tests => 6;
 use strict;
 use warnings;
 
@@ -9,7 +9,7 @@ BEGIN {
 
 use List::Util qw(first sum);
 use Slic3r;
-use Slic3r::Geometry qw(scale);
+use Slic3r::Geometry qw(scale PI);
 use Slic3r::Test;
 
 {
@@ -38,4 +38,42 @@ use Slic3r::Test;
         'first_layer_extrusion_width applies to everything on first layer';
 }
 
+{
+    my $config = Slic3r::Config->new_from_defaults;
+    $config->set('bridge_speed', 99);
+    $config->set('bridge_flow_ratio', 1);
+    $config->set('cooling', 0);                 # to prevent speeds from being altered
+    $config->set('first_layer_speed', '100%');  # to prevent speeds from being altered
+    
+    my $test = sub {
+        my $print = Slic3r::Test::init_print('overhang', config => $config);
+        my @E_per_mm = ();
+        Slic3r::GCode::Reader->new->parse(my $gcode = Slic3r::Test::gcode($print), sub {
+            my ($self, $cmd, $args, $info) = @_;
+        
+            if ($info->{extruding} && $info->{dist_XY} > 0) {
+                if (($args->{F} // $self->F) == $config->bridge_speed*60) {
+                    push @E_per_mm, $info->{dist_E} / $info->{dist_XY};
+                }
+            }
+        });
+        my $expected_mm3_per_mm = ($config->nozzle_diameter->[0]**2) * PI/4 * $config->bridge_flow_ratio;
+        my $expected_E_per_mm = $expected_mm3_per_mm / ((($config->filament_diameter->[0]/2)**2)*PI);
+        ok !(defined first { abs($_ - $expected_E_per_mm) > 0.01 } @E_per_mm),
+            'expected flow when using bridge_flow_ratio = ' . $config->bridge_flow_ratio;
+    };
+    
+    $config->set('bridge_flow_ratio', 0.5);
+    $test->();
+    $config->set('bridge_flow_ratio', 2);
+    $test->();
+    $config->set('extrusion_width', 0.4);
+    $config->set('bridge_flow_ratio', 1);
+    $test->();
+    $config->set('bridge_flow_ratio', 0.5);
+    $test->();
+    $config->set('bridge_flow_ratio', 2);
+    $test->();
+}
+
 __END__
diff --git a/xs/src/Flow.cpp b/xs/src/Flow.cpp
index 19aa807d..6f66f70d 100644
--- a/xs/src/Flow.cpp
+++ b/xs/src/Flow.cpp
@@ -9,7 +9,8 @@ Flow::new_from_config_width(FlowRole role, const ConfigOptionFloatOrPercent &wid
     if (height <= 0 && bridge_flow_ratio == 0) CONFESS("Invalid flow height supplied to new_from_config_width()");
     
     float w;
-    if (!width.percent && width.value == 0) {
+    // use automatic extrusion width if user left 0 or we need a bridge flow
+    if ((!width.percent && width.value == 0) || bridge_flow_ratio > 0) {
         w = Flow::_width(role, nozzle_diameter, height, bridge_flow_ratio);
     } else {
         w = width.get_abs_value(height);