diff --git a/polygons.h b/polygons.h
index 471cdf9..168b225 100644
--- a/polygons.h
+++ b/polygons.h
@@ -1,8 +1,6 @@
 #ifndef POLYGONS_H_INCLUDED
 #define POLYGONS_H_INCLUDED
 
-// extern ball spaceship;
-
 #include "vec2d.h"
 
 #include <gtk/gtk.h>
@@ -15,6 +13,26 @@ class polygon {
     std::vector<vec2d> points;
 
     void draw(cairo_t* cr) const;
+
+    polygon& set_center(vec2d c) {
+        center = c;
+        return *this;
+    }
+
+    polygon& set_angle(double a) {
+        angle = a;
+        return *this;
+    }
+
+    polygon& translate(vec2d delta) {
+        center += delta;
+        return *this;
+    }
+
+    polygon& rotate(double delta) {
+        angle += delta;
+        return *this;
+    }
 };
 
 extern polygon* polygons;
@@ -22,7 +40,6 @@ extern uint n_polygons;
 
 extern void polygons_init_state();
 extern void polygons_update_state();
-// extern void polygon_control (double dx, double dy);
 extern void polygons_draw(cairo_t* cr);
 
 #endif