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Pygame

:material-circle-edit-outline: 约 462 个字 :fontawesome-solid-code: 39 行代码 :material-image-multiple-outline: 2 张图片 :material-clock-time-two-outline: 预计阅读时间 5 分钟

Fonts and text renders

  • Pygame renders text to a surface with the font module
  • Font module can locate and load a font as a Font object
    How to render text:
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    font = pygame.font.Font(None, 36)
text = font.render("Hello, World", True, (255, 0, 0))
screen.blit(text, (200, 200))
    the font.render() method returns a surface with the text rendered on it
    a_font.size(): method returns the size of the text , a turple of width and height a_font.get_height(): method returns the height of the font a_font.get_linesize(): method returns the height of a line of text a_font.metrics:returns a list with one turple per character in ttext

Sprites(Object-Oriented Models)

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class MySprite(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.Surface((50, 50))
        self.image.fill((255, 0, 0))
        self.rect = self.image.get_rect()
        self.rect.topleft = (100, 100)
the usage of sprites:
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sprite = MySprite()
sprite_group = pygame.sprite.Group()
sprite_group.add(sprite)
sprite_group.draw(screen)
sprite_group.draw(screen): method draws all the sprites in the group to the screen sprite operations with group:
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sprite_group.update()
sprite_group.clear(screen, background)
sprite_group.remove(sprite)
Group.clear(surface, background): clears the sprites from the screen
Group.draw(surface): draws the sprites to the screen
alt text
LayerUpdates class:
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class LayerUpdates(pygame.sprite.LayeredUpdates):
    def __init__(self):
        pygame.sprite.LayeredUpdates.__init__(self)
        self.add(MySprite())
a group within group
DirtySprite class:
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class DirtySprite(pygame.sprite.DirtySprite):
    def __init__(self):
        pygame.sprite.DirtySprite.__init__(self)
        self.image = pygame.Surface((50, 50))
        self.image.fill((0, 255, 0))
        self.rect = self.image.get_rect()
        self.rect.topleft = (200, 200)
DirtySprite.dirty: attribute to indicate whether the sprite needs to be updated
DirtySprite.dirty = 1: set the sprite to be updated DirtySprite.dirty = 0: set the sprite not to be updated LayeredDirty class:
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class LayeredDirty(pygame.sprite.LayeredDirty):
    def __init__(self):
        pygame.sprite.LayeredDirty.__init__(self)
        self.add(DirtySprite())
Collision Detection:will be discussioned in chapter five

Animation

Animation: a series of images displayed in rapid succession to create the illusion of movement

how to make shure that the animation is smooth?

  1. slow the game loop down to a consistent number
  2. measure the time between frames and adjust the speed of the animation accordingly

Approach 1: Slowerloop
a tick() method to control the speed of the game loop

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def tick(self):
    self.clock.tick(30)
Approach 2: Measure delta value: the time cost of the last frame(game loop)
delta=clock.tick()
it will return number of milliseconds since last time

Randomness

Randomness: a key element in games random.randint(a, b): returns a random integer between a and b random.choice(sequence): returns a random element from a sequence random.shuffle(sequence): shuffles the sequence in place random.seed(): initializes the random number generator LCG: Linear Congruential Generator: a simple algorithm to generate random numbers \(X_{n+1}=(aX_n+c)mod m\) \(ex: X_{n+1}=(1664525X_n+1013904223)mod 2^{32}\) LCG has a specific period, and the period is the maximum number of random numbers that can be generated before the sequence repeats

PRNG: Pseudo-Random Number Generator

PRNG: a deterministic algorithm that generates a sequence of numbers that approximates the properties of random numbers
a good PRNG should have a long period, be unpredictable, and have a uniform distribution

Random distributions

Uniform distribution: each number has an equal chance of being selected
Normal distribution: a bell-shaped curve with the mean at the center
Asymmetric distribution: a distribution that is not symmetrical: Dropping the lowest roll, reroll the lowest alt text
Critical Hit: a game mechanic that allows a player to deal extra damage
How to construct a critical hit?

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def roll_with_crit():
    roll = random.randint(1, 20)
    if roll < crit_threshold:
        return 2 * random.randint(1, 6)
    return roll
Arbitrary distribution: a distribution that is not uniform, normal, or asymmetric
use die-size to control the scale