Space shooting Lesson 10: score (painting and writing)

Space shooting No 10 course ： Score （ Painting and writing ）

This is us. “Shmup” Project No 7 part . If you haven't read through the previous section , Please from The first 1 part Start . In this lesson , We will start to maintain our scores , And learn how to display text on the screen .

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Show scores

It's very simple to show players' scores ： We only need one score Variable , We initialize to 0, And every time a bullet destroys a meteor . Because we have meteors of different sizes , And big meteors are easier to hit than small ones , So it makes sense to get more points when hitting a smaller meteor .

We will call this variable and initialize it before the game loop ：

for i in range(8):
    m = Mob()
    all_sprites.add(m)
    mobs.add(m)
score = 0

# Game loop
running = True

The score should be allocated according to the size of the meteor , We can use what we used before radius attribute . The largest meteor image is about 100 px wide , Its radius is 100 * .85 / 2 = 43 px, The radius of the smallest meteor is about 8 Pixels . therefore , If we subtract the radius from a larger number 50, for instance , Big meteor gives 7 branch , The smallest meteor gives 42 branch .

# check to see if a bullet hit a mob
    hits = pygame.sprite.groupcollide(mobs, bullets, True, True)
    for hit in hits:
        score += 50 - hit.radius
        m = Mob()
        all_sprites.add(m)
        mobs.add(m)

Render text

Now we have a variable to save our scores , But we need to be able to draw it on the screen , It's a little tricky . stay Pygame Drawing text in is a little complicated , It takes a few steps . If you want to draw text multiple times , So it makes sense to create a function , We're going to call draw_text Function to handle it . The parameters of this function will be ：

• surf- We want to draw the surface of the text
• text- The string we want to display
• x, y- Location

We also need to choose a font . If the font you selected does not exist on the computer you are using , There may be problems . We can do that by using pygame.font.match_font() Search the system for the closest matching font to solve this problem .

Here is draw_text function ：

font_name = pygame.font.match_font('arial')
def draw_text(surf, text, size, x, y):
    font = pygame.font.Font(font_name, size)
    text_surface = font.render(text, True, WHITE)
    text_rect = text_surface.get_rect()
    text_rect.midtop = (x, y)
    surf.blit(text_surface, text_rect)

Drawing fonts onto the screen requires accurate calculation of the required pixel patterns - Computer graphics terminology is “ Rendering ”. This is it. font.render() Functions perform operations . however , You may want to know True The purpose of the parameter . This is an open / Closing is called Anti-Aliasing Function options .

Anti-Aliasing

If you have ever tried to draw something manually with pixels , So you know it's very difficult to draw curves on a square grid - You will eventually get a jagged shape . This jagged shape is called “ sawtooth ”, You can see an example here ：

Due to aliasing , first “a” The characters look very blocky . Anti-Aliasing It's the way modern computers make text on the screen look less jagged . They achieve this by mixing the pixels at the edge of the shape with the background color . In this example , You can see black “a” Surrounded by gray pixels . Shrink the hours , The font looks very clean and curved .

Show scores

Now? , We are ready to display the score on the screen . We just need to add it to our drawing section , The score is displayed at the top center of the screen ：

# Draw / render
    screen.fill(BLACK)
    screen.blit(background, background_rect)
    all_sprites.draw(screen)
    draw_text(screen, str(score), 18, WIDTH / 2, 10)

this is it ！ thereinafter , We will add sounds and music to make it more interesting ！

The complete code of this part

# KidsCanCode - Game Development with Pygame video series
# Shmup game - part 7
# Video link: https://www.youtube.com/watch?v=U8yyrpuplwc
# Adding score (and drawing text)
import pygame
import random
from os import path

img_dir = path.join(path.dirname(__file__), 'img')

WIDTH = 480
HEIGHT = 600
FPS = 60

# define colors
WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)
YELLOW = (255, 255, 0)

# initialize pygame and create window
pygame.init()
pygame.mixer.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("Shmup!")
clock = pygame.time.Clock()

font_name = pygame.font.match_font('arial')
def draw_text(surf, text, size, x, y):
    font = pygame.font.Font(font_name, size)
    text_surface = font.render(text, True, WHITE)
    text_rect = text_surface.get_rect()
    text_rect.midtop = (x, y)
    surf.blit(text_surface, text_rect)

class Player(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.transform.scale(player_img, (50, 38))
        self.image.set_colorkey(BLACK)
        self.rect = self.image.get_rect()
        self.radius = 20
        # pygame.draw.circle(self.image, RED, self.rect.center, self.radius)
        self.rect.centerx = WIDTH / 2
        self.rect.bottom = HEIGHT - 10
        self.speedx = 0

    def update(self):
        self.speedx = 0
        keystate = pygame.key.get_pressed()
        if keystate[pygame.K_LEFT]:
            self.speedx = -8
        if keystate[pygame.K_RIGHT]:
            self.speedx = 8
        self.rect.x += self.speedx
        if self.rect.right > WIDTH:
            self.rect.right = WIDTH
        if self.rect.left < 0:
            self.rect.left = 0

    def shoot(self):
        bullet = Bullet(self.rect.centerx, self.rect.top)
        all_sprites.add(bullet)
        bullets.add(bullet)

class Mob(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image_orig = random.choice(meteor_images)
        self.image_orig.set_colorkey(BLACK)
        self.image = self.image_orig.copy()
        self.rect = self.image.get_rect()
        self.radius = int(self.rect.width * .85 / 2)
        # pygame.draw.circle(self.image, RED, self.rect.center, self.radius)
        self.rect.x = random.randrange(WIDTH - self.rect.width)
        self.rect.y = random.randrange(-150, -100)
        self.speedy = random.randrange(1, 8)
        self.speedx = random.randrange(-3, 3)
        self.rot = 0
        self.rot_speed = random.randrange(-8, 8)
        self.last_update = pygame.time.get_ticks()

    def rotate(self):
        now = pygame.time.get_ticks()
        if now - self.last_update > 50:
            self.last_update = now
            self.rot = (self.rot + self.rot_speed) % 360
            new_image = pygame.transform.rotate(self.image_orig, self.rot)
            old_center = self.rect.center
            self.image = new_image
            self.rect = self.image.get_rect()
            self.rect.center = old_center

    def update(self):
        self.rotate()
        self.rect.x += self.speedx
        self.rect.y += self.speedy
        if self.rect.top > HEIGHT + 10 or self.rect.left < -25 or self.rect.right > WIDTH + 20:
            self.rect.x = random.randrange(WIDTH - self.rect.width)
            self.rect.y = random.randrange(-100, -40)
            self.speedy = random.randrange(1, 8)

class Bullet(pygame.sprite.Sprite):
    def __init__(self, x, y):
        pygame.sprite.Sprite.__init__(self)
        self.image = bullet_img
        self.image.set_colorkey(BLACK)
        self.rect = self.image.get_rect()
        self.rect.bottom = y
        self.rect.centerx = x
        self.speedy = -10

    def update(self):
        self.rect.y += self.speedy
        # kill if it moves off the top of the screen
        if self.rect.bottom < 0:
            self.kill()

# Load all game graphics
background = pygame.image.load(path.join(img_dir, "starfield.png")).convert()
background_rect = background.get_rect()
player_img = pygame.image.load(path.join(img_dir, "playerShip1_orange.png")).convert()
bullet_img = pygame.image.load(path.join(img_dir, "laserRed16.png")).convert()
meteor_images = []
meteor_list = ['meteorBrown_big1.png', 'meteorBrown_med1.png', 'meteorBrown_med1.png',
               'meteorBrown_med3.png', 'meteorBrown_small1.png', 'meteorBrown_small2.png',
               'meteorBrown_tiny1.png']
for img in meteor_list:
    meteor_images.append(pygame.image.load(path.join(img_dir, img)).convert())

all_sprites = pygame.sprite.Group()
mobs = pygame.sprite.Group()
bullets = pygame.sprite.Group()
player = Player()
all_sprites.add(player)
for i in range(8):
    m = Mob()
    all_sprites.add(m)
    mobs.add(m)
score = 0

# Game loop
running = True
while running:
    # keep loop running at the right speed
    clock.tick(FPS)
    # Process input (events)
    for event in pygame.event.get():
        # check for closing window
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_SPACE:
                player.shoot()

    # Update
    all_sprites.update()

    # check to see if a bullet hit a mob
    hits = pygame.sprite.groupcollide(mobs, bullets, True, True)
    for hit in hits:
        score += 50 - hit.radius
        m = Mob()
        all_sprites.add(m)
        mobs.add(m)

    # check to see if a mob hit the player
    hits = pygame.sprite.spritecollide(player, mobs, False, pygame.sprite.collide_circle)
    if hits:
        running = False

    # Draw / render
    screen.fill(BLACK)
    screen.blit(background, background_rect)
    all_sprites.draw(screen)
    draw_text(screen, str(score), 18, WIDTH / 2, 10)
    # *after* drawing everything, flip the display
    pygame.display.flip()

pygame.quit()

The first 8 part ： Sound and music