Tag: python game

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!

Hello there, sorry for a little bit late today because I am busy setting up my old website which is now ready for me to add in more articles into it, if you are interested in more programming articles then do visit this site because I am going to create a brand new laptop application project with python and if you are a python lover then go ahead and bookmark this site and visit it starting from tomorrow!. Gaming Directional, which is the site we both are in now will only concentrate on writing game code so if you want to read other programming articles besides the game one then do visit the above mentioned site instead. OK so much for that lets look at another of the new class I have created for the previous pygame project, which is the Overlap class.

We will call the Overlap class object on every game loop to determine the following:-

1) Does the player ship gets hit by the enemy missile? If so then we will remove that enemy missile.
2) Does the player ship hits one of the enemy ship? If so then we will remove that enemy ship.
3) Does the enemy ship gets hit by a player missile? If so then remove both of them.

We will not going to do anything on the player ship yet even if it gets hit by the enemy ship or missile because we will deal with this issue later on.

Here is the entire Overlap class.

from pygame.locals import *

class Overlap(object):

    def __init__(self):
        pass # nothing here

    # is player and enemy, player missile, enemy missile overlap
    def iseOverlap(self, player, em, pm):

        self.player_rect = Rect(player.pos.x, player.pos.y, player.width, player.height)

        for i in range(len(em.enemy_list)): # is player collides with enemy

            self.em_rect = Rect(em.enemy_list[i].x, em.enemy_list[i].y, em.width, em.height)
            if (self.player_rect.colliderect(self.em_rect)):
                em.enemy_list[i].on = False

        for i in range(len(em.enemy_missile_manager.missile_list)): # is enemy missile hits player

            self.em_rect = Rect(em.enemy_missile_manager.missile_list[i].x, em.enemy_missile_manager.missile_list[i].y, em.enemy_missile_manager.width, em.enemy_missile_manager.height)
            if (self.player_rect.colliderect(self.em_rect)):
                em.enemy_missile_manager.missile_list[i].on = False

        for i in range(len(em.enemy_list)): # is player missile hits enemy

            self.em_rect = Rect(em.enemy_list[i].x, em.enemy_list[i].y, em.width, em.height)

            for j in range(len(pm.missile_list)):

                self.pm_rect = Rect(pm.missile_list[j].x, pm.missile_list[j].y, pm.width, pm.height)

                if (self.em_rect.colliderect(self.pm_rect)):
                    em.enemy_list[i].on = False
                    pm.missile_list[j].on = False

We also need to edit the Game Manager class like this.

from Player import Player
from Background import Background
from MissileManager import MissileManager
from EnemyManager import EnemyManager
from Overlap import Overlap
import pygame

class GameManager(object):

    def __init__(self, scene):

        self.scene = scene
        self.player = Player(self.scene)
        self.background = Background(self.scene)
        self.missile_manager = MissileManager(self.scene, self.player)
        self.enemy_manager = EnemyManager(self.scene, self.player)
        self.overlap_manager = Overlap()
        self.load_music()
        self.play_music()

    def load_music(self):
        pygame.mixer_music.load('Music/winternight.ogg')

    def play_music(self):
        pygame.mixer_music.play(-1) #play the music infinite time

    def set_player_x(self, _x):
        self.player.setX(_x)

    def set_player_y(self, _y):
        self.player.setY(_y)

    def set_missile_strike(self, strike):
        self. missile_manager.setStrike(True)

    def update(self):
        self.player.update()
        self.missile_manager.update()
        self.enemy_manager.update()
        self.isOverlap()

    # check for player, enemy, missiles overlap
    def isOverlap(self):
        self.overlap_manager.iseOverlap(self.player, self.enemy_manager, self. missile_manager)

    def draw(self):
        self.background.draw()
        self.player.draw()
        self.missile_manager.draw()
        self.enemy_manager.draw()
        pygame.display.flip()

And here is the outcome

Alright then, after this class we will continue to create the recycle class tomorrow which we will use to recycle and then reuse back the game object so we do not need to create a new one which will increase the burden of the computer’s processor.

Before we go ahead and create the Game Manager class we will need to take out all the code which are related to the missile manager in the main python file as shown in the previous article and put them all under a single missile manager class. Here is the modify version of the missile manager class as compared with the previous version.. This class will take in both the scene as well as the player object to start with.

from Missile import Missile
from GameSprite import GameSprite
from pygame.locals import *

class MissileManager(object):

    def __init__(self, scene, player):
        self.scene = scene
        self.player = player
        self.missile_count = 10
        self.missile_list = []
        self.image = 'Asset/missile.png'
        self.width = 20
        self.height = 20
        self.rect = Rect(0, 0, self.width, self.height)
        self.strike = False
        self.strike_again = 0
        # initialize game sprite object
        self.sprite = GameSprite(self.image, self.rect)

    def setStrike(self, strike):

        # set the missile strike flag
        self.strike = strike
        self.strike_again += 1

    def create_missile(self, x, y):
        if(self.missile_count >= 0):
            self.missile_surface = self.sprite.getImage()
            self.missile_list.append(Missile(self.missile_surface, x, y))
            self.missile_count -= 1

    def update(self):
        if (self.strike == True and self.strike_again > 1):
            self.strike_again = 0
            x, y = self.player.get()
            self.create_missile(x + 5, y - 8)  # create more missile
        self.missile_update()
        self.check_boundary()

    def missile_update(self):

        for item in list(self.missile_list):
            if(item.on == False):
                self.missile_list.remove(item)
                self.missile_count += 1
            else:
                item.update()

    def check_boundary(self):
        for i in range(len(self.missile_list)):
            if (self.missile_list[i].y < 0):
                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)

As you can see we will use a single update method to control both the missile update and the check boundary method. We have also included a new draw method to draw the missiles on the game scene. The missile manager class does not need to return the missile list anymore to the main file so the previous method has been totally removed. Finally we have a set strike method to turn the strike flag on or off depends on whether the space key has been pressed or released.

That is it for this one, now lets us look at the Game Manager class in the next chapter.

After a few days of rest, today I have continued my pygame project again and will keep on working on my new pygame projects without stopping anymore starting from today. Today I have created two game sprite classes to render the player and the background on the game scene.

The player sprite class is almost the same as the background sprite class, the only reason I have created two game sprite classes is because I want to create extra custom methods for the background sprite class.

The player class (GameSprite.py) will look like this.

import pygame

class GameSprite(object):

    def __init__(self, image, rect):
        self.image = image
        self.rect = rect
        self.sprite = pygame.image.load(image).convert_alpha() # return a pygame surface object

    def getImage(self):  # this method will return a subsurface which is the child of the self.sprite surface
        return self.sprite.subsurface(self.rect)

The background class (BgSprite.py) is almost the same for now.

import pygame

class BgSprite(object):

    def __init__(self, image, rect):
        self.image = image
        self.rect = rect
        self.sprite = pygame.image.load(image).convert() # return a pygame surface object

    def getImage(self):  # this method will return a subsurface which is the child of the self.sprite surface
        return self.sprite.subsurface(self.rect)

Here is the modify version of the main file, the background and the player image has been displayed.

import sys, pygame
from pygame import math as mt
from pygame.locals import *
from GameSprite import GameSprite
from BgSprite import BgSprite

pygame.init()
size = width, height = 660, 660
pygame.display.set_caption("Hello World") # set the title of the window
screen = pygame.display.set_mode(size)

pygame.mixer_music.load('Music/winternight.ogg')
pygame.mixer_music.play(-1)

player_sprite = 'Asset/player.png'
bg_sprite = 'Asset/bg.png'

player_pos = mt.Vector2(width/2, height/2) # initialize the position of the player sprite

rect = Rect(0, 0, 40, 40)  # the rectangle object uses to clip the sprite area
game_sprite = GameSprite(player_sprite, rect)
game_sprite_surface = game_sprite.getImage()  # get the player sprite surface

rect = Rect(0, 0, 660, 660)
game_bg_sprite = BgSprite(bg_sprite, rect)
game_bg_surface = game_bg_sprite.getImage()  # get the background sprite surface

player_draw_pos = mt.Vector2(player_pos.x , player_pos.y)
bg_draw_pos = mt.Vector2(0 , 0)

while True:

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.mixer_music.stop()
            sys.exit()

    screen.blit(game_bg_surface, bg_draw_pos)
    screen.blit(game_sprite_surface, player_draw_pos)
    pygame.display.flip()

Run the above program will get this outcome.

The files under the project file explorer will now look like this.

In the next session we will deal with keyboard input so we can move the player around the game scene.