In this article we will continue to create a new missile pool object which will be used to recycle the enemy missile object just like the pool object which will be used to recycle the enemy ship object in the previous article. Basically we will use back the previous object pool class which we have created earlier and then add in a new obtain missile method which takes in the x and y coordinate of the enemy ship at that moment that we can later use as the starting point for the missile object returns from the pool. Here is the class.
class Objectpool(object):
def __init__(self, size):
self.size = size
self.count = 0
self.elist = [None]*size
def recycle(self, item):
if (self.count < self.size):
self.elist[self.count] = item
self.count += 1
def obtain(self):
if (self.count > 0):
self.count -= 1
self.item = self.elist[self.count]
self.elist[self.count] = None
self.item.missile_count = 1
return self.item
def obtain_missile(self, x, y): # get the missile object from the pool
if (self.count > 0):
self.count -= 1
self.item = self.elist[self.count]
self.elist[self.count] = None
self.item.x = x
self.item.y = y
self.item.on = True
return self.item
def getSize(self):
return self.count
That is it, now lets amend the Enemy Missile Manager class by adding in the create missile from pool method which will be used to obtain the old missile object from the object pool.
from GameSprite import GameSprite
from pygame.locals import *
from Enemymissile import Enemymissile
class EnemyMissileManager(object):
def __init__(self, scene, player):
self.scene = scene
self.player = player
self.missile_count = 60
self.missile_list = []
self.image = 'Asset/e_missile.png'
self.width = 20
self.height = 20
self.rect = Rect(0, 0, self.width, self.height)
# initialize game sprite object
self.sprite = GameSprite(self.image, self.rect)
def create_missile(self, x, y):
if(self.missile_count >= 0):
self.missile_surface = self.sprite.getImage()
self.missile_list.append(Enemymissile(self.missile_surface, x, y))
self.missile_count -= 1
def create_missile_from_pool(self, x, y, pool):
if (self.missile_count >= 0):
self.missile_list.append(pool.obtain_missile(x, y))
self.missile_count -= 1
def update(self, pool):
self.missile_update(pool)
self.check_boundary()
def missile_update(self, pool):
for item in list(self.missile_list):
if(item.on == False):
self.missile_list.remove(item)
self.missile_count += 1
pool.recycle(item)
else:
item.update()
def check_boundary(self):
for i in range(len(self.missile_list)):
if (self.missile_list[i].y + self.missile_list[i].height > 660):
self.missile_list[i].on = False
def draw(self):
# blit the missile on the scene
for i in range(len(self.missile_list)):
self.scene.blit(self.missile_list[i].missile_surface, self.missile_list[i].missile_pos)
We now need to do the last step which is to edit the Enemy Manager class.
from Enemy import Enemy
from GameSprite import GameSprite
from pygame.locals import *
from EnemyMissileManager import EnemyMissileManager
import random
from Objectpool import Objectpool
class EnemyManager(object):
def __init__(self, scene, player):
self.enemy_missile_manager = EnemyMissileManager(scene, player)
self.scene = scene
self.player = player
self.enemy_count = 10
self.missile_count = 60
self.enemy_list = []
self.image = 'Asset/enemy0.png'
self.width = 30
self.height = 30
self.rect = Rect(0, 0, self.width, self.height)
self.more_enemy = 0
self.y = -50
self.boundary_width = 660
self.boundary_height = 660
self.object_pool = Objectpool(self.enemy_count)
self.missile_object_pool = Objectpool(self.missile_count)
# initialize game sprite object
self.sprite = GameSprite(self.image, self.rect)
def create_enemy(self, x, y):
if(self.enemy_count > 0):
if(self.object_pool.getSize() > 0): # get the ship from object pool if the pool is not empty
self.enemy_list.append(self.object_pool.obtain())
else:
self.enemy_surface = self.sprite.getImage()
self.enemy_list.append(Enemy(self.enemy_surface, x, y))
self.enemy_count -= 1
def update(self):
if (self.more_enemy > 600):
self.more_enemy = 0
x = random.randint(30, self.boundary_width - 50)
self.create_enemy(x , self.y) # create more enemy
else:
self.more_enemy += 1 # increase time
self.enemy_update()
self.check_boundary()
self.create_enemy_missile()
self.enemy_missile_manager.update(self.missile_object_pool)
def create_enemy_missile(self):
for item in list(self.enemy_list):
if(self.player.pos.y - item.y < 100 and abs(self.player.pos.x - item.x) < 60 ):
if (item.missile_count > 0):
if (self.missile_object_pool.getSize() > 0):
self.enemy_missile_manager.create_missile_from_pool(item.x + 5, item.y + 4, self.missile_object_pool)
else:
self.enemy_missile_manager.create_missile(item.x + 5, item.y + 4)
item.missile_count -= 1
def enemy_update(self):
for item in list(self.enemy_list):
if(item.on == False):
self.enemy_list.remove(item)
self.enemy_count += 1
item.y = self.y
item.on = True
self.object_pool.recycle(item)
else:
item.update()
def check_boundary(self):
for i in range(len(self.enemy_list)):
if (self.enemy_list[i].y > self.boundary_height):
self.enemy_list[i].on = False
def draw(self):
# blit the enemy on the scene
for i in range(len(self.enemy_list)):
self.scene.blit(self.enemy_list[i].enemy_surface, self.enemy_list[i].enemy_pos)
# draw enemy missiles
self.enemy_missile_manager.draw()
That is it! With that we will be able to reuse the old enemy missile object instead of creating a new one. The next article will still be dealing with the pool object and this time we will create an object pool for the player missile object!
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