add center sphere to small z pattern

grid/ui/pattern.py

@@ -161,7 +161,7 @@ class SmallZPattern(Pattern):
 
         sphere_on_circle = 6
         for i in range(sphere_on_circle):
-            if i == 2 or i == 3:
+            if i == 2 or i == 3 or i == 5 or i == 0:
                 continue
             else:
                 self.addToGroup(
@@ -177,8 +177,16 @@ class SmallZPattern(Pattern):
         points = self.generate_circle_points(
             self.center_x, self.center_y, self.SPACE_BETWEEN_SPHERE, sphere_on_circle
         )
+        self.addToGroup(
+            LineGraphicsItem(self.center_x, self.center_y, points[1][0], points[1][1], self)
+        )
+        self.addToGroup(
+            LineGraphicsItem(self.center_x, self.center_y, points[4][0], points[4][1], self)
+        )
         # Remove left and right sphere
         del points[0]
         del points[2]
         for x, y in points:
             self.addToGroup(random_sphere_factory(x, y))
+
+        self.addToGroup(HPSphereGraphicsItem(self.center_x, self.center_y))