added collision

circleshape.py

@@ -13,6 +13,13 @@ class CircleShape(pygame.sprite.Sprite):
         self.velocity = pygame.Vector2(0, 0)
         self.radius = radius
 
+    def is_colided(self,other_circle):
+        distance = self.position.distance_to(other_circle.position)
+        if other_circle.radius + self.radius <= distance:
+            return True
+        else:
+            return False
+
     def draw(self, screen):
         # sub-classes must override
         pass