From 407de02fe4a6ce93808d694271fee636bc0ab80e Mon Sep 17 00:00:00 2001
From: Mark Hindess <soft-github@temporalanomaly.com>
Date: Thu, 18 Apr 2013 19:29:05 +0100
Subject: [PATCH] Use binary search for get_layer_range. Gives a 13% speed up
 on Teethy_Tiki.stl (thing:49334) with default settings on my laptop. When
 $self->layers->[0]->slice_z == $min_z the returned $min_layer value is 0
 rather than the (incorrect?) -1 returned by the old code.

---
 lib/Slic3r/Print/Object.pm | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/lib/Slic3r/Print/Object.pm b/lib/Slic3r/Print/Object.pm
index d7dd3f70e..d4052fcc9 100644
--- a/lib/Slic3r/Print/Object.pm
+++ b/lib/Slic3r/Print/Object.pm
@@ -95,18 +95,33 @@ sub get_layer_range {
     
     # $min_layer is the uppermost layer having slice_z <= $min_z
     # $max_layer is the lowermost layer having slice_z >= $max_z
-    my ($min_layer, $max_layer) = (0, undef);
-    for my $i (0 .. $#{$self->layers}) {
-        if ($self->layers->[$i]->slice_z >= $min_z) {
-            $min_layer = $i - 1;
-            for my $k ($i .. $#{$self->layers}) {
-                if ($self->layers->[$k]->slice_z >= $max_z) {
-                    $max_layer = $k - 1;
-                    last;
-                }
-            }
+    my ($min_layer, $max_layer);
+
+    my ($bottom, $top) = (0, $#{$self->layers});
+    while (1) {
+        my $mid = $bottom+int(($top - $bottom)/2);
+        if ($mid == $top || $mid == $bottom) {
+            $min_layer = $mid;
             last;
         }
+        if ($self->layers->[$mid]->slice_z >= $min_z) {
+            $top = $mid;
+        } else {
+            $bottom = $mid;
+        }
+    }
+    $top = $#{$self->layers};
+    while (1) {
+        my $mid = $bottom+int(($top - $bottom)/2);
+        if ($mid == $top || $mid == $bottom) {
+            $max_layer = $mid;
+            last;
+        }
+        if ($self->layers->[$mid]->slice_z < $max_z) {
+            $bottom = $mid;
+        } else {
+            $top = $mid;
+        }
     }
     return ($min_layer, $max_layer);
 }