game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleep

def check_events(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets):
    """Respond to keypresses and mouse events."""
    for event in pygame.event.get():
        if event.type==pygame.QUIT:
            sys.exit()

        elif event.type==pygame.KEYDOWN:
            check_keydown_events(event,ai_settings,screen,ship,bullets) 

        elif event.type == pygame.KEYUP:
            check_keyup_events(event,ship)

        elif event.type==pygame.MOUSEBUTTONDOWN:
            mouse_x,mouse_y=pygame.mouse.get_pos()
            check_play_button(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets,mouse_x,mouse_y)

def check_play_button(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets,mouse_x,mouse_y):
    button_clicked=play_button.rect.collidepoint(mouse_x,mouse_y)

    if button_clicked and not stats.game_active:
        #Reset the game settings.
        ai_settings.initialize_dynamic_settings()
        pygame.mouse.set_visible(False)

        stats.reset_stats()
        stats.game_active=True

        sb.prep_score()
        sb.prep_high_score()
        sb.prep_level()
        sb.prep_ships()

        aliens.empty()
        bullets.empty()

        create_fleet(ai_settings,screen,ship,aliens)
        ship.center_ship()

def update_screen(ai_settings,screen,stats,sb,ship,aliens,bullets,play_button):
    """Update images ont he screen and flip to the new screen."""
    #Redraw the screen during each pass through the loop.
    screen.fill(ai_settings.bg_color)
    #Redraw all bullets behind ship and aliens.
    for bullet in bullets.sprites():
        bullet.draw_bullet()
    ship.blitme()
    aliens.draw(screen)
    sb.show_score()

    #Draw the play button if the game is inactive.
    if not stats.game_active:
        play_button.draw_button()

    #Make the most recently drawn screen visible
    pygame.display.flip()


def check_keydown_events(event,ai_settings,screen,ship,bullets):
    """Respond to keypresses."""
    if event.key==pygame.K_RIGHT:
        ship.moving_right = True
    elif event.key==pygame.K_LEFT:
        ship.moving_left=True 
    elif event.key==pygame.K_SPACE:
        #Create a new bullet and add it to the bullets group.
        fire_bullet(ai_settings,screen,ship,bullets)
    elif event.key== pygame.K_q:
        sys.exit()

def check_keyup_events(event,ship):
    """Respond to key releases."""
    if event.key==pygame.K_RIGHT:
        ship.moving_right=False
    elif event.key==pygame.K_LEFT:
        ship.moving_left=False


def update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets):
    """Update position of bullets and get rid of old bullets."""
    #update bullet positions.
    bullets.update()
    #Get rid of bulltes that have disappeared.
    for bullet in bullets.copy():
        if bullet.rect.bottom<=0:
            bullets.remove(bullet)
    check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets)

def check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets):

    #check for any bullet that have hit aliens.
    #if so,get rid of the bullet and the alien.
    collisions=pygame.sprite.groupcollide(bullets,aliens,True,True)
    if collisions:
        for aliens in collisions.values():
            stats.score+=ai_settings.alien_points
            sb.prep_score()
        check_high_score(stats,sb)

    
    if len(aliens)==0:
        #Destory existing bullets and create new fleet>
        bullets.empty()
        ai_settings.increase_speed()
        stats.level+=1
        sb.prep_level()
        create_fleet(ai_settings,screen,ship,aliens)

def fire_bullet(ai_settings,screen,ship,bullets):
    if len(bullets)<ai_settings.bullets_allowed:
        new_bullet=Bullet(ai_settings,screen,ship)
        bullets.add(new_bullet)

def create_fleet(ai_settings,screen,ship,aliens):
    """create a full fleet of aliens."""
    #create an alien and find the numebr fo aliens in a row.
    #Spacing between each alien is equal to one alien width.
    alien=Alien(ai_settings,screen)
    number_aliens_x=get_number_aliens_x(ai_settings,alien.rect.width)
    number_rows=get_number_rows(ai_settings,ship.rect.height,alien.rect.height)

    #Create the fleet of aliens.
    for row_number in range(number_rows):
        for alien_number in range(number_aliens_x):
            create_alien(ai_settings,screen,aliens,alien_number,row_number)

       

def get_number_aliens_x(ai_settings,alien_width):
    """Determine the number of aliens that fit in a row."""
    available_space_x=ai_settings.screen_width-2*alien_width
    number_aliens_x=int(available_space_x/(2*alien_width))
    return number_aliens_x

def create_alien(ai_settings,screen,aliens,alien_number,row_number):
    """Create an alien and place it in the row."""
    alien=Alien(ai_settings,screen)
    alien_width=alien.rect.width
    alien.x=alien_width+2*alien_width*alien_number
    alien.rect.x=alien.x
    alien.rect.y=alien.rect.height+2*alien.rect.height*row_number
    aliens.add(alien)

def get_number_rows(ai_settings,ship_height,alien_height):
    """Determient he number of rows of aliend that fit on the scren."""
    available_space_y=(ai_settings.screen_height-(3*alien_height)-ship_height)
    number_rows=int(available_space_y/(2*alien_height))
    return number_rows

def update_aliens(ai_settings,screen,stats,sb,ship,aliens,bullets):
    check_fleet_edges(ai_settings,aliens)
    aliens.update()
    #look for alien-ship collsions.
    if pygame.sprite.spritecollideany(ship,aliens):
        ship_hit(ai_settings,screen,stats,sb, ship,aliens,bullets)
    #Look for aliens hitting the bottom of the screen.
    check_aliens_bottom(ai_settings,screen,stats,sb,ship,aliens,bullets)

def check_fleet_edges(ai_settings,aliens):
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings,aliens)
            break

def change_fleet_direction(ai_settings,aliens):
    for alien in aliens.sprites():
        alien.rect.y+=ai_settings.fleet_drop_speed
    ai_settings.fleet_direction*=-1

def ship_hit(ai_settings,screen,stats,sb,ship,aliens,bullets):
    """Respond to ship being hit by alien."""
    if stats.ships_left>0:
        #Decrement ships_left.
        stats.ships_left-=1
        sb.prep_ships()

        #Empty the list of aliens and bullets.
        aliens.empty()
        bullets.empty()

        #Create a new fleet and center the ship.
        create_fleet(ai_settings,screen,ship,aliens)
        ship.center_ship()

        #Pause.
        sleep(0.5)
    else:
        stats.game_active=False

def check_aliens_bottom(ai_settings,screen,stats,sb,ship,aliens,bullets):
    """Check if any aliens have reched the bottom of the screen."""
    screen_rect =screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom>=screen_rect.bottom:
            #Treat this the same as if the ship got hit.
            ship_hit(ai_settings,screen,stats,sb,ship,aliens,bullets)
            break


def check_high_score(stats,sb):
    if stats.score > stats.high_score:
        stats.high_score=stats.score
        sb.prep_high_score()