More files for convex_hull

xs/src/Geometry.cpp

@@ -0,0 +1,46 @@
+#include "Geometry.hpp"
+#include <algorithm>
+
+namespace Slic3r {
+
+static bool
+sort_points (Point a, Point b)
+{
+    return (a.x < b.x) || (a.x == b.x && a.y < b.y);
+}
+
+void
+convex_hull(Points points, Polygon &hull)
+{
+    assert(points.size() >= 2);
+    // sort input points
+    std::sort(points.begin(), points.end(), sort_points);
+
+    typedef const Point* PointPtr;
+    PointPtr* out_hull = (PointPtr*)malloc(points.size()*2*sizeof(PointPtr));
+
+    /* lower hull */
+    size_t k = 0;
+    for (Points::const_iterator it = points.begin(); it != points.end(); ++it) {
+        while (k >= 2 && it->ccw(out_hull[k-2], out_hull[k-1]) <= 0) --k;
+        Point pz = *&*it;
+        out_hull[k++] = &*it;
+    }
+
+    /* upper hull */
+    size_t t = k+1;
+    for (Points::const_iterator it = points.end() - 2; it != points.begin(); --it) {
+        while (k >= t && it->ccw(out_hull[k-2], out_hull[k-1]) <= 0) --k;
+        out_hull[k++] = &*it;
+    }
+
+    // we assume hull is empty
+    hull.points.reserve(k);
+    for (size_t i = 0; i < k; ++i) {
+        hull.points.push_back(*(out_hull[i]));
+    }
+
+    free(out_hull);
+}
+
+}

xs/src/Geometry.hpp

@@ -0,0 +1,12 @@
+#ifndef slic3r_Geometry_hpp_
+#define slic3r_Geometry_hpp_
+
+#include "Polygon.hpp"
+
+namespace Slic3r {
+
+void convex_hull(Points points, Polygon &hull);
+
+}
+
+#endif

xs/t/14_geometry.t

@@ -0,0 +1,22 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Slic3r::XS;
+use Test::More tests => 2;
+
+{
+    my @points = (
+        Slic3r::Point->new(100,100),
+        Slic3r::Point->new(100,200),
+        Slic3r::Point->new(200,200),
+        Slic3r::Point->new(200,100),
+        Slic3r::Point->new(150,150),
+    );
+    my $hull = Slic3r::Geometry::convex_hull(\@points);
+    isa_ok $hull, 'Slic3r::Polygon', 'convex_hull returns a Polygon';
+    is scalar(@$hull), 4, 'convex_hull returns the correct number of points';
+}
+
+__END__

xs/xsp/Geometry.xsp

@@ -0,0 +1,23 @@
+%module{Slic3r::XS};
+
+%{
+#include <myinit.h>
+#include "Geometry.hpp"
+%}
+
+%package{Slic3r::Geometry};
+
+%{
+
+Polygon*
+convex_hull(points)
+    Points      points
+    PREINIT:
+        const char* CLASS = "Slic3r::Polygon";
+    CODE:
+        RETVAL = new Polygon ();
+        convex_hull(points, *RETVAL);
+    OUTPUT:
+        RETVAL
+
+%}