Building a SPACE INVADER game using pygames in python(using Python3.7.4V)

Created by Pritam Choudhury

Introduction to pygame

Pygame is a cross-platform set of Python modules designed for writing video games. It includes computer graphics and sound libraries designed to be used with the Python programming language.

Pygame uses the Simple DirectMedia Layer (SDL) library,[a] with the intention of allowing real-time computer game development without the low-level mechanics of the C programming language and its derivatives. This is based on the assumption that the most expensive functions inside games can be abstracted from the game logic, making it possible to use a high-level programming language, such as Python, to structure the game.

Let’s Start coding ….

Here is the python code to this wonderful and easy warship game:

import pygame
import random
import math
from pygame import mixer

# initialization
pygame.init()

# create the screen
screen = pygame.display.set_mode((800, 600))
done = True

# background
background = pygame.image.load(‘background.png’)
mixer.music.load(“background.mpeg”)
mixer.music.play(-1)

# icon and caption
pygame.display.set_caption(“Space Invader pro”)
icon = pygame.image.load(‘space-invaders.png’)
pygame.display.set_icon(icon)

# player
playerImg = pygame.image.load(‘space-invaders.png’)
playerX = 370
playerY = 500

def player(x, y):
screen.blit(playerImg, (x, y))

# ENEMY
enemyImg = []
enemyX = []
enemyY = []
enemyX_change = []
enemyY_change = []
no_of_enemies = 6
for i in range(no_of_enemies):
enemyImg.append(pygame.image.load(‘enemy.png’))
enemyX.append(random.randint(0, 735))
enemyY.append(random.randint(50, 150))
enemyX_change.append(5)
enemyY_change.append(50)

def enemy(x, y, i):
screen.blit(enemyImg[i], (x, y))

#Score Board
score_value = 0
font=pygame.font.Font(‘freesansbold.ttf’,40)
scoreX=10
scoreY=10

def display_score(x,y):
score=font.render(“Score : “+ str(score_value),True,(255,255,255))
screen.blit(score,(x,y))

#GAME OVER

gameover_font=pygame.font.Font(‘freesansbold.ttf’,75)

def gameover():
gameover_text= gameover_font.render(“GAME OVER “, True, (255, 255, 255))
screen.blit(gameover_text, (200,250))

# bullet
bulletImg = pygame.image.load(‘bullet.png’)
bulletX = 0
bulletY = 500
bulletX_change = 0
bulletY_change = 10
bullet_state = “ready”

def bullet(x, y):
global bullet_state
bullet_state = “fire”
screen.blit(bulletImg, (x + 16, y + 10))

# collision check function
def iscollision(enemyX, enemyY, bulletX, bulletY):
distance = math.sqrt((math.pow(enemyX — bulletX, 2)) + (math.pow(enemyY — bulletY, 2)))
if distance < 27:
return True
else:
return False

# game loop
while done:
screen.fill((0, 0, 0))
screen.blit(background, (0, 0))
for event in pygame.event.get():
if event.type == pygame.QUIT:
done = False
pressed = pygame.key.get_pressed()
if pressed[pygame.K_UP]: playerY -= 2
if pressed[pygame.K_DOWN]: playerY += 2
if pressed[pygame.K_LEFT]: playerX -= 2
if pressed[pygame.K_RIGHT]: playerX += 2
if pressed[pygame.K_SPACE]:
if bullet_state is “ready”:
bullet_sound=mixer.Sound(“shoot.wav”)
bullet_sound.play()
bulletX = playerX
bulletY = playerY
bullet(bulletX, bulletY)

# Player movement
if playerX >= 736:
playerX = 736
if playerX <= 0:
playerX = 0
if playerY >= 536:
playerY = 536
if playerY <= 0:
playerY = 0

# enemy movement
for i in range(no_of_enemies):

#conditions for game over
if enemyY[i] > 480:
for j in range(no_of_enemies):
enemyY[j]=2000
gameover()
break

enemyX[i] += enemyX_change[i]
if enemyX[i] >= 736:
enemyX_change[i] = -3
enemyY[i] += enemyY_change[i]
elif enemyX[i] <= 0:
enemyX_change[i] = 3
enemyY[i] += enemyY_change[i]

# collision
collision = iscollision(enemyX[i], enemyY[i], bulletX, bulletY)
if collision:
collision_sound = mixer.Sound(“explosion.wav”)
collision_sound.play()
bulletY = playerY
bullet_state = “ready”
score_value += 1
enemyX[i] = random.randint(0, 735)
enemyY[i] = random.randint(0, 150)

enemy(enemyX[i], enemyY[i], i)

# Bullet movement
if bulletY <= 0:
bulletY = 500
bullet_state = “ready”
if bullet_state is “fire”:
bullet(bulletX, bulletY)

bulletY -= bulletY_change

player(playerX, playerY)
display_score(scoreX,scoreY)

pygame.display.update()