added asteroid splitting

asteroid.py

@@ -1,6 +1,7 @@
 import circleshape
 import pygame
 import constants
+import random
 
 class Asteroid(circleshape.CircleShape):
     
@@ -14,3 +15,18 @@ class Asteroid(circleshape.CircleShape):
 
     def update(self, dt):
         self.position += self.velocity * dt
+    def split(self):
+        self.kill()
+
+        if self.radius <= constants.ASTEROID_MIN_RADIUS:
+            return
+        else:
+            rand_angle = random.uniform(20, 50)
+            new_velocity1 = self.velocity.rotate(rand_angle)
+            new_velocity2 = self.velocity.rotate(-rand_angle)
+            new_radius = self.radius - constants.ASTEROID_MIN_RADIUS
+            
+            asteroid1 = Asteroid(self.position.x, self.position.y, new_radius)
+            asteroid1.velocity = new_velocity1 * 1.2
+            asteroid2 = Asteroid(self.position.x, self.position.y, new_radius)
+            asteroid2.velocity = new_velocity2 * 1.2

main.py

@@ -58,7 +58,7 @@ def main():
         for asteroid in asteroids:
             for shot in shots:
                 if shot.is_colided(asteroid):
-                    asteroid.kill()
+                    asteroid.split()
                     shot.kill()
         pygame.display.flip()
         tick = clock.tick(60)