Fixed type error

xs/src/libslic3r/Line.cpp

@@ -182,14 +182,14 @@ Line::extend_start(double distance)
 bool
 Line::intersection(const Line& line, Point* intersection) const
 {
-    double denom = ((line.b.y - line.a.y)*(this->b.x - this->a.x)) -
-                   ((line.b.x - line.a.x)*(this->b.y - this->a.y));
+    double denom = ((double)(line.b.y - line.a.y)*(this->b.x - this->a.x)) -
+                   ((double)(line.b.x - line.a.x)*(this->b.y - this->a.y));
 
-    double nume_a = ((line.b.x - line.a.x)*(this->a.y - line.a.y)) -
-                    ((line.b.y - line.a.y)*(this->a.x - line.a.x));
+    double nume_a = ((double)(line.b.x - line.a.x)*(this->a.y - line.a.y)) -
+                    ((double)(line.b.y - line.a.y)*(this->a.x - line.a.x));
 
-    double nume_b = ((this->b.x - this->a.x)*(this->a.y - line.a.y)) -
-                    ((this->b.y - this->a.y)*(this->a.x - line.a.x));
+    double nume_b = ((double)(this->b.x - this->a.x)*(this->a.y - line.a.y)) -
+                    ((double)(this->b.y - this->a.y)*(this->a.x - line.a.x));
     
     if (fabs(denom) < EPSILON) {
         if (fabs(nume_a) < EPSILON && fabs(nume_b) < EPSILON) {

xs/t/06_polygon.t

@@ -5,7 +5,7 @@ use warnings;
 
 use List::Util qw(first);
 use Slic3r::XS;
-use Test::More tests => 20;
+use Test::More tests => 21;
 
 use constant PI => 4 * atan2(1, 1);
 
@@ -73,6 +73,17 @@ ok $cw_polygon->contains_point(Slic3r::Point->new(150,150)), 'cw contains_point'
     is_deeply $polygon->centroid->pp, [150,150], 'centroid';
 }
 
+{
+    my $polygon = Slic3r::Polygon->new(
+        [50000000,  100000000],
+        [300000000, 102000000],
+        [50000000,  104000000],
+    );
+    my $line = Slic3r::Line->new([175992032,102000000], [47983964,102000000]);
+    my $intersection = $polygon->intersection($line);
+    is_deeply $intersection->pp, [50000000, 102000000], 'polygon-line intersection';
+}
+
 # this is not a test: this just demonstrates bad usage, where $polygon->clone gets
 # DESTROY'ed before the derived object ($point), causing bad memory access
 if (0) {

xs/xsp/Polygon.xsp

@@ -42,6 +42,12 @@
     std::string wkt();
     Points concave_points(double angle);
     Points convex_points(double angle);
+    Clone<Point> intersection(Line* line)
+        %code{%
+            Point p;
+            (void)THIS->intersection(*line, &p);
+            RETVAL = p;
+        %};
 %{
 
 Polygon*