From b84be0deb57a2a34348991f829856daeed58c478 Mon Sep 17 00:00:00 2001
From: Joseph Lenox <lordofhyphens@gmail.com>
Date: Sat, 5 Jan 2019 18:45:59 -0600
Subject: [PATCH] Fix division by zero when min=max layer heights (#4672)

* #4670 Avoid a division by 0 crash if max_layer_height == min_layer_height (use scaling of 1.0).

* #4670 Limits -> Layer Height Limits

* Add config validation to Config.pm for adaptive slicing

* Also cover min_layer_height >= max_layer_height

* Correct logic for min/max layer height.
---
 lib/Slic3r/Config.pm                   | 3 +++
 lib/Slic3r/GUI/Plater/SplineControl.pm | 6 +++++-
 lib/Slic3r/GUI/PresetEditor.pm         | 2 +-
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/Slic3r/Config.pm b/lib/Slic3r/Config.pm
index 1de0bdda3..4549fade3 100644
--- a/lib/Slic3r/Config.pm
+++ b/lib/Slic3r/Config.pm
@@ -270,6 +270,9 @@ sub validate {
         die "Spiral vase mode is not compatible with support material\n"
             if $self->support_material || $self->support_material_enforce_layers > 0;
     }
+    # --min-layer-height and --max-layer-height
+        die "Max layer height should be greater than min layer height."
+            if $self->adaptive_slicing && ($self->max_layer_height < $self->min_layer_height);
     
     # extrusion widths
     {
diff --git a/lib/Slic3r/GUI/Plater/SplineControl.pm b/lib/Slic3r/GUI/Plater/SplineControl.pm
index f47a91af2..447cd8ca7 100644
--- a/lib/Slic3r/GUI/Plater/SplineControl.pm
+++ b/lib/Slic3r/GUI/Plater/SplineControl.pm
@@ -267,7 +267,11 @@ sub _update_canvas_size {
     my @size = ($canvas_w - 2*$padding, $canvas_h - 2*$padding);
     $self->{canvas_size} = [@size];
     
-    $self->{scaling_factor_x} = $size[0]/($self->{max_layer_height} - $self->{min_layer_height});
+    if ($self->{max_layer_height} > $self->{min_layer_height}) {
+        $self->{scaling_factor_x} = $size[0]/($self->{max_layer_height} - $self->{min_layer_height});
+    } else {
+        $self->{scaling_factor_x} = 1.0;
+    }
     $self->{scaling_factor_y} = $size[1]/$self->{object_height};
 }
 
diff --git a/lib/Slic3r/GUI/PresetEditor.pm b/lib/Slic3r/GUI/PresetEditor.pm
index 256394042..823805401 100644
--- a/lib/Slic3r/GUI/PresetEditor.pm
+++ b/lib/Slic3r/GUI/PresetEditor.pm
@@ -1534,7 +1534,7 @@ sub _build_extruder_pages {
             $optgroup->append_single_option_line('nozzle_diameter', $extruder_idx);
         }
         {
-            my $optgroup = $page->new_optgroup('Limits');
+            my $optgroup = $page->new_optgroup('Layer Height Limits');
             $optgroup->append_single_option_line($_, $extruder_idx)
                for qw(min_layer_height max_layer_height);
         }