update demo

src/experimental/demo/voronoi_lines_demo.scad

@@ -1,14 +1,28 @@
 use <hull_polyline2d.scad>;
 use <experimental/voronoi_lines.scad>;
+use <experimental/convex_hull.scad>;
 
 pt_nums = 50;
 width = 1;
 points = [for(i = [0:pt_nums - 1]) rands(-50, 50, 2)];   
-    
-for(line = voronoi_lines(points)) {
-    hull_polyline2d(
-        line, 
-        width = width,
-        $fn = 4
-    );
-}
+  
+intersection() {  
+    for(line = voronoi_lines(points)) {
+        hull_polyline2d(
+            line, 
+            width = width,
+            $fn = 4
+        );
+    }
+    hull()
+    #for(p = points) {
+        translate(p)
+            circle(.5);
+    }
+}
+
+hull_pts = convex_hull(points);
+hull_polyline2d(
+    concat(hull_pts, [hull_pts[0]]), 
+    width = width, $fn = 4
+);