Implemented split_at_index() and split_at_first_point() for Polygon

xs/src/Polygon.hpp

@@ -16,6 +16,8 @@ namespace Slic3r {
 class Polygon : public MultiPoint {
     public:
     Lines lines();
+    Polyline* split_at_index(int index);
+    Polyline* split_at_first_point();
 };
 
 typedef std::vector<Polygon> Polygons;
@@ -31,6 +33,25 @@ Polygon::lines()
     return lines;
 }
 
+Polyline*
+Polygon::split_at_index(int index)
+{
+    Polyline* poly = new Polyline;
+    for (int i = index; i < this->points.size(); i++) {
+        poly->points.push_back( this->points[i] );
+    }
+    for (int i = 0; i < index; i++) {
+        poly->points.push_back( this->points[i] );
+    }
+    return poly;
+}
+
+Polyline*
+Polygon::split_at_first_point()
+{
+    return this->split_at_index(0);
+}
+
 }
 
 #endif

xs/t/06_polygon.t

@@ -4,7 +4,7 @@ use strict;
 use warnings;
 
 use Slic3r::XS;
-use Test::More tests => 4;
+use Test::More tests => 6;
 
 my $square = [  # ccw
     [100, 100],
@@ -27,4 +27,7 @@ is_deeply [ map $_->pp, @$lines ], [
     [ [100, 200], [100, 100] ],
 ], 'polygon lines';
 
+is_deeply $polygon->split_at_first_point->pp, $square, 'split_at_first_point';
+is_deeply $polygon->split_at_index(2)->pp, [ @$square[2,3,0,1] ], 'split_at_index';
+
 __END__

xs/xsp/Polygon.xsp

@@ -16,6 +16,10 @@
     void scale(double factor);
     void translate(double x, double y);
     Lines lines();
+    Polyline* split_at_index(int index)
+        %code{% const char* CLASS = "Slic3r::Polyline"; RETVAL = THIS->split_at_index(index); %};
+    Polyline* split_at_first_point()
+        %code{% const char* CLASS = "Slic3r::Polyline"; RETVAL = THIS->split_at_first_point(); %};
 %{
 
 Polygon*