from turtle import Turtle, mainloop import random import math class LaserCannon(Turtle): def __init__(self, xmin, xmax, ymin, ymax): super().__init__() self.screen = self.getscreen() self.screen.bgcolor("light green") self.screen.setworldcoordinates(xmin, ymin, xmax, ymax) self.screen.onclick(self.aim) #we need to create a method for aim  self.screen.onkey(self.shoot, "s") #we need to create a method for shoot  self.screen.onkey(self.quit, "q") #we need to create a method for quit   def aim(self, x, y): heading = self.towards(x, y) self.setheading(heading) def shoot(self): Bomb(self.heading(), 15) #we do not know at this point what this does, but we know we are creating a Bomb object  #first argument is the direction, the second argument is the speed   def quit(self): self.screen.bye() class BoundedTurtle(Turtle): #any object bounded by the screen  def __init__(self, speed, xmin=-200, xmax=200, ymin=0, ymax=400): #the bounded turtle object has default values  super().__init__() self.xmin = xmin self.xmax = xmax self.ymin = ymin self.ymax = ymax self.speed = speed def outOfBounds(self): xpos, ypos = self.position() #tuple indicating the current position of the BoundedTurtle  out = False # assume the BoundedTurtle is inside of the bounds  if xpos or xpos > self.xmax: out = True  if ypos or ypos > self.ymax: out = True  return out def move(self): self.forward(self.speed) if self.outOfBounds(): self.remove() #we need a method to remove the object from the screen  else: self.getscreen().ontimer(self.move, 200) #this method .ontimer creates a callback to .move in the current instance  # every 200 seconds  def remove(self): self.hideturtle() class Bomb(BoundedTurtle): def __init__(self, initHeading, speed): super().__init__(speed) self.initHeading = initHeading self.shape("circle") self.color('red', 'red') self.resizemode('user') self.setheading(initHeading) self.up() self.turtlesize(.25) self.getscreen().ontimer(self.move, 100) def distance(self, other): #calculate distance between two BoundedTurtles for collision detection  p1 = self.position() p2 = other.position() a = p1[0] - p2[0] b = p1[1] - p2[1] dist = math.sqrt(a**2 + b**2) return dist #overriding superclass move  def move(self): exploded = False  self.forward(self.speed) #collision detection  for i in Alien.getAliens(): # this assumes that Alien in a class that can be iterated and that contains a method  # .getAliens  if self.distance(i) # if bomb and alien are within 5 units then the bomb should trigger and explode  i.remove() # i is an Alien object, thus Alien should contain a .remove method  exploded = True   if self.outOfBounds() or exploded: self.remove() else: self.getscreen().ontimer(self.move, 100) class Alien(BoundedTurtle): alienList = [] #class global variable to hold all objects that we identify as "aliens"   @staticmethod def getAliens(): return [x for x in Alien.alienList if x.alive] def __init__(self, speed, xmin, xmax, ymin, ymax): super().__init__(speed, xmin, xmax, ymin, ymax) self.getscreen().tracer(0) self.up() if 'PurpleAlien.gif' not in self.getscreen().getshapes(): self.getscreen().addshape("PurpleAlien.gif") #this is needed especially when the game starts  self.shape('PurpleAlien.gif') self.goto(random.randint(xmin+1, xmax-1), ymax-20) self.setheading(random.randint(250, 290)) self.getscreen().tracer(1) Alien.alienList = [x for x in Alien.alienList if x.alive] Alien.alienList.append(self) self.alive = True  self.getscreen().ontimer(self.move, 200) #rely on the move method from the superclass   #override remove method  def remove(self): self.alive = False  self.hideturtle() #Game engine class AlienInvaders: def __init__(self, xmin, xmax, ymin, ymax): self.xmin = xmin self.xmax = xmax self.ymin = ymin self.ymax = ymax def play(self): self.mainWin = LaserCannon(self.xmin, self.xmax, self.ymin, self.ymax).getscreen() self.mainWin.ontimer(self.addAlien, 1000) # this means we need to code a .addAlien method  self.mainWin.listen() #we add this so that all event handlers are running (or threads are running)  mainloop() def addAlien(self): if len(Alien.getAliens()) #matches the default values for the BoundedTurtle object game.play() #game engine at work

Problem 6 (50 XP) Modify the spaceinvades game so that the LaserCanon0 object automatically fires a Bomb onclik, rather than with the use of the "s" key. The LaserCanon0 still changes direction towards the direction of the (x,y) coordinate you click. This modification makes the game easier to play since it does not require the player to press "s" after changing direction to fire a Bomb