I am working on a game which involves the user to control a spaceship (player in code) and and shoot aliens (enemy in code) spawned randomly in the surface.
As of now, I have only successfully made one alien spawn at a time. How do I add say, 6 aliens simultaneously, that respawn (in random places of the surface) after a bullet hits it?
import pygame
import random
import math
# for initialising pygame (req for every pygame app)
pygame.init()
# making the basic window (dimensions must be written inside a tuple )
screen = pygame.display.set_mode((500, 500))
# background
background = pygame.image.load('C:/Users/aryan/Downloads/background.jpg')
# load and set the logo
logo = pygame.image.load('C:/Users/aryan/Downloads/bp.png') # directory of logo
pygame.display.set_icon(logo)
pygame.display.set_caption("space wars") # program name
# define a variable to control the main loop
running = True
# player
playerimg = pygame.image.load('C:/Users/aryan/Downloads/spaceship.png')
playerX = 218 # x and y coordinates of image
playerY = 350
playerxchange = 0 # this will be the change in movement in x direction of our image
playerychange = 0 # this will be the change in movement in y direction of our image
def player(x, y):
screen.blit(playerimg, (x, y)) # blit draws our image on the surface(basically the background)
# syntax for blit(imagename, (xcoordinate,ycoordinate))
# enemy
enemyimg = pygame.image.load('C:/Users/aryan/Downloads/enemy.png')
enemyX = random.randint(0, 464)
enemyY = random.randint(0, 30)
enemyxchange = 0.2
enemyychange = 40
# game over
overimg = pygame.image.load('C:/Users/aryan/Downloads/gameover.png')
# bullet
bulletimg = pygame.image.load('C:/Users/aryan/Downloads/bullet.png')
bulletX = 0
bulletY = 350
bulletxchange = 0
bulletychange = 1
bullet_state = "ready" # "ready" you cant see bullet on screen
# "fire" you can see bullet firing
bullets = [] # bullets is a list that contains the coordinates of every bullet
score = 0
font30 = pygame.font.SysFont(None, 30)
# Functions
def enemy(x, y):
screen.blit(enemyimg, (x, y)) # blit draws our image on the surface(basically the background)
# syntax for blit(imagename, (xcoordinate,ycoordinate))
def firebullet(x, y):
global bullet_state
bullet_state = "ready"
bullets.append([x + 12, y + 6]) # Creating a new bullet
def iscollision(enemyX, enemyY, bulletX, bulletY):
distance = math.sqrt(math.pow(enemyX-bulletX, 2)+ math.pow(enemyY-bulletY,2)) # distance formula
if distance <= 20:
return True
else:
return False
def TextScore(game):
text2 = font30.render("Your Score is: " + str(game), True, (37, 97, 188))
screen.blit(text2, (10, 45))
# main loop
while running:
screen.fill((120, 120, 120)) # in order (r, g, b) . (0, 0, 0) is black (255, 0, 0) is red...
screen.blit(background, (0, 0))
# event handling, gets all event from the event queue
for event in pygame.event.get():
# only do something if the event is of type QUIT
if event.type == pygame.QUIT:
# change the value to False, to exit the main loop
running = False
# checking keystroke
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_RIGHT:
playerxchange += 0.3 # change in movement will be 0.2 towards the right
if event.key == pygame.K_LEFT:
playerxchange -= 0.3 # change in movement will be 0.2 towards the right
if event.key == pygame.K_UP:
playerychange -= 0.3
if event.key == pygame.K_DOWN:
playerychange += 0.3
if event.key == pygame.K_SPACE:
bullet_state = "fire"
firebullet(playerX, playerY)
if event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT or event.key == pygame.K_DOWN or event.key == pygame.K_UP:
playerxchange = 0
playerychange = 0
playerY += playerychange
playerX += playerxchange # the value of playerx changes by +- 0.1 depending on keystroke
if playerX <= -64: # this teleports the spaceship from left end to right end
playerX = 564
elif playerX >= 564: # this teleports spaceship from right end to left
playerX = -64
if playerY >= 436: # this prevents spaceship from leaving vertically
playerY = 436
if playerY <= 0:
playerY = 0
# enemy movement
enemyX += enemyxchange
if enemyY >= 476:
enemyY = 476
enemyYchange = 0
enemyXchange = 0
if enemyX <= 0:
enemyxchange = 0.2
enemyY += enemyychange
elif enemyX >= 465:
enemyxchange = -0.2
enemyY += enemyychange
# bullet movement
if bullet_state == "fire":
firebullet(playerX, playerY)
for bullet in bullets:
screen.blit(bulletimg, (bullet[0], bullet[1])) # Print a bullet
bullet[0] -= bulletxchange # Updates its position
bullet[1] -= bulletychange
if bullet[1] < 0:
bullets.remove(bullet)
# collision
for bullet in bullets: # Use a for-loop to iterate through all the bullets in the list.
collision = iscollision(enemyX, enemyY, bullet[0], bullet[1])
if collision: # Test if a single bullet collides with the enemy inside the loop.
score += 1
print(score)
bullets.remove(bullet) # Remove the bullet from the list when it collides with the enemy.
enemyX = random.randint(0, 476) # if collision takes place, alien respawns
enemyY = random.randint(0, 30)
TextScore(score)
player(playerX, playerY) # player method is called AFTER screen.fill otherwise the screen will fill after image has been blitted
enemy(enemyX, enemyY)
pygame.display.update() # necessary for events to keep updating
Create an Enemy class with a move and a draw method (see Classes):
class Enemy:
def __init__(self):
self.x = random.randint(0, 476)
self.y = 20
self.moveX = 0.2
self.moveY = 40
def move(self):
self.x += self.moveX
if self.y >= 476:
self.y = 476
self.moveY = 0
self.moveX = 0
if self.x <= 0:
self.moveX = 0.2
self.y += self.moveY
elif self.x >= 465:
self.moveX = -0.2
self.y += self.moveY
def draw(self):
screen.blit(enemyimg, (self.x, self.y))
Create a number of enemies and store them in a list (enemy_list ) instead of the global variables enemyX, enemyY, enemyxchange and enemyychange:
enemyimg = pygame.image.load('C:/Users/aryan/Downloads/enemy.png')
enemy_list = []
for i in range(5):
new_enemy = Enemy()
enemy_list.append(new_enemy)
move and draw the enemies in a loop. For the collision test, you need to check if any of the bullets hits any of the enemies. Therefore, the collision test has to be done in nested loops. Note that the loop that goes through the bullets has to be the inner loop because the bullets are removed from the list:
# main loop
while running:
# [...]
for enemy in enemy_list:
enemy.move()
# [...]
# collision
for enemy in enemy_list:
for bullet in bullets: # Use a for-loop to iterate through all the bullets in the list.
collision = iscollision(enemy.x, enemy.y, bullet[0], bullet[1])
if collision: # Test if a single bullet collides with the enemy inside the loop.
score += 1
print(score)
bullets.remove(bullet) # Remove the bullet from the list when it collides with the enemy.
enemy.x = random.randint(0, 476) # if collision takes place, alien respawns
enemy.y = random.randint(0, 30)
# [...]
for enemy in enemy_list:
enemy.draw()
Complete code:
import pygame
import random
import math
# for initialising pygame (req for every pygame app)
pygame.init()
# making the basic window (dimensions must be written inside a tuple )
screen = pygame.display.set_mode((500, 500))
# background
background = pygame.image.load('C:/Users/aryan/Downloads/background.jpg')
# load and set the logo
logo = pygame.image.load('C:/Users/aryan/Downloads/bp.png') # directory of logo
pygame.display.set_icon(logo)
pygame.display.set_caption("space wars") # program name
# define a variable to control the main loop
running = True
# player
playerimg = pygame.image.load('C:/Users/aryan/Downloads/spaceship.png')
playerX = 218 # x and y coordinates of image
playerY = 350
playerxchange = 0 # this will be the change in movement in x direction of our image
playerychange = 0 # this will be the change in movement in y direction of our image
def player(x, y):
screen.blit(playerimg, (x, y)) # blit draws our image on the surface(basically the background)
# syntax for blit(imagename, (xcoordinate,ycoordinate))
class Enemy:
def __init__(self):
self.x = random.randint(0, 476)
self.y = 20
self.moveX = 0.2
self.moveY = 40
def move(self):
self.x += self.moveX
if self.y >= 476:
self.y = 476
self.moveY = 0
self.moveX = 0
if self.x <= 0:
self.moveX = 0.1
self.y += self.moveY
elif self.x >= 465:
self.moveX = -0.1
self.y += self.moveY
def draw(self):
screen.blit(enemyimg, (self.x, self.y))
# enemy
enemyimg = pygame.image.load('C:/Users/aryan/Downloads/enemy.png')
enemy_list = []
for i in range(5):
new_enemy = Enemy()
enemy_list.append(new_enemy)
# game over
overimg = pygame.image.load('C:/Users/aryan/Downloads/gameover.png')
# bullet
bulletimg = pygame.image.load('C:/Users/aryan/Downloads/bullet.png')
bulletX = 0
bulletY = 350
bulletxchange = 0
bulletychange = 1
bullet_state = "ready" # "ready" you cant see bullet on screen
# "fire" you can see bullet firing
bullets = [] # bullets is a list that contains the coordinates of every bullet
score = 0
font30 = pygame.font.SysFont(None, 30)
def firebullet(x, y):
global bullet_state
bullet_state = "ready"
bullets.append([x + 12, y + 6]) # Creating a new bullet
def iscollision(enemyX, enemyY, bulletX, bulletY):
distance = math.sqrt(math.pow(enemyX-bulletX, 2)+ math.pow(enemyY-bulletY,2)) # distance formula
if distance <= 20:
return True
else:
return False
def TextScore(game):
text2 = font30.render("Your Score is: " + str(game), True, (37, 97, 188))
screen.blit(text2, (10, 45))
# main loop
while running:
screen.fill((120, 120, 120)) # in order (r, g, b) . (0, 0, 0) is black (255, 0, 0) is red...
screen.blit(background, (0, 0))
# event handling, gets all event from the event queue
for event in pygame.event.get():
# only do something if the event is of type QUIT
if event.type == pygame.QUIT:
# change the value to False, to exit the main loop
running = False
# checking keystroke
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_RIGHT:
playerxchange += 0.3 # change in movement will be 0.2 towards the right
if event.key == pygame.K_LEFT:
playerxchange -= 0.3 # change in movement will be 0.2 towards the right
if event.key == pygame.K_UP:
playerychange -= 0.3
if event.key == pygame.K_DOWN:
playerychange += 0.3
if event.key == pygame.K_SPACE:
bullet_state = "fire"
firebullet(playerX, playerY)
if event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT or event.key == pygame.K_DOWN or event.key == pygame.K_UP:
playerxchange = 0
playerychange = 0
playerY += playerychange
playerX += playerxchange # the value of playerx changes by +- 0.1 depending on keystroke
if playerX <= -64: # this teleports the spaceship from left end to right end
playerX = 564
elif playerX >= 564: # this teleports spaceship from right end to left
playerX = -64
if playerY >= 436: # this prevents spaceship from leaving vertically
playerY = 436
if playerY <= 0:
playerY = 0
for enemy in enemy_list:
enemy.move()
# bullet movement
if bullet_state == "fire":
firebullet(playerX, playerY)
for bullet in bullets:
screen.blit(bulletimg, (bullet[0], bullet[1])) # Print a bullet
bullet[0] -= bulletxchange # Updates its position
bullet[1] -= bulletychange
if bullet[1] < 0:
bullets.remove(bullet)
# collision
for enemy in enemy_list:
for bullet in bullets: # Use a for-loop to iterate through all the bullets in the list.
collision = iscollision(enemy.x, enemy.y, bullet[0], bullet[1])
if collision: # Test if a single bullet collides with the enemy inside the loop.
score += 1
print(score)
bullets.remove(bullet) # Remove the bullet from the list when it collides with the enemy.
enemy.x = random.randint(0, 476) # if collision takes place, alien respawns
enemy.y = random.randint(0, 30)
TextScore(score)
player(playerX, playerY) # player method is called AFTER screen.fill otherwise the screen will fill after image has been blitted
for enemy in enemy_list:
enemy.draw()
pygame.display.update() # necessary for events to keep updating
If you want to spawn non-overlapping enemies, see the answers to the following questions: