问游戏平台2D中的敌人运动

EN

# As a list
enemy_image = pygame.image.load( "doomba.png" ).convert_alpha()
enemy_rect  = enemy_image.get_rect()
enemy_rect.center = ( x, y )
enemy1 = [ enemy_rect, enemy_image, PACE_SIZE, TURN_SIZE ]

# As a sprite class
class Enemy( pygame.sprite.Sprite ):
    def __init__( self, x, y, bitmap, pace=5, turn_after=20 ):
            """ Create a new Enemy at that is drawn at (x,y) as the /bitmap/.
                It moves /pace/ pixels each step, left, then right     """
        pygame.sprite.Sprite.__init__( self )
        self.image = pygame.image.load( bitmap ).convert_alpha()
        self.rect  = self.image.get_rect()
        self.rect.center = ( x, y )         # location
        self.pace_size   = pace             # How big each step is
        self.pace_count  = 0                # distance moved
        self.direction   = -1               # Start moving left (-x)
        self.turn_after  = turn_after       # distance limit

    def update( self ):
        """ Implement the movement algorithm """
        # Walk pace in the current direction
        self.pace_count += 1
        self.rect.x     += self.direction * self.pace_size     # Move some pixels

        # We need to turn around if walked enough paces in the same direction
        if ( self.pace_count >= self.turn_after ):
            # Turn around!
            self.direction *= -1           # reverses the pixel distance
            self.pace_count = 0            # reset the pace count

        # We also should change direction if we hit the screen edge
        if ( self.rect.x <= 0 ):
            self.direction  = 1             # turn right
            self.pace_count = 0
        elif ( self.rect.x >= WINDOW_WIDTH - self.rect.width ):
            self.direction  = -1
            self.pace_count = 0

def update( self ):
    """ Implement the movement algorithm """
    time_now = pygame.time.get_ticks()               # what time is it
    if ( time_now > self.pace_time + self.speed ):   # time to move again?
        self.pace_time = time_now                    # remember move time

        # Walk pace in the current direction
        self.pace_count += 1

import pygame

# Window size
WINDOW_WIDTH    = 600
WINDOW_HEIGHT   = 400
WINDOW_SURFACE  = pygame.HWSURFACE|pygame.DOUBLEBUF

DARK_BLUE = (   3,   5,  54)

class Enemy( pygame.sprite.Sprite ):
    def __init__( self, x, y, pace, bitmap, turn_after=20, speed=100 ):
        """ Create a new Enemy at that is drawn at (x,y) as the /bitmap/.
            It moves /pace/ pixels left, then right   """
        pygame.sprite.Sprite.__init__( self )    
        self.image = pygame.image.load( bitmap ).convert_alpha()
        self.rect  = self.image.get_rect()
        self.rect.center = ( x, y )         # location
        self.pace_size   = pace             # How big each step is
        self.pace_count  = 0                # distance moved
        self.direction   = -1               # Start moving left (-x)
        self.turn_after  = turn_after       # distance limit
        self.speed       = speed            # Milliseconds per pace
        self.pace_time   = 0                # time of last step

    def update( self ):
        """ Implement the movement algorithm """
        time_now = pygame.time.get_ticks()               # what time is it
        if ( time_now > self.pace_time + self.speed ):   # is it time to move again
            self.pace_time = time_now

            # Walk pace in the current direction
            self.pace_count += 1
            self.rect.x     += self.direction * self.pace_size     # Move some pixels

            # We need to turn around if walked enough paces in the same direction
            if ( self.pace_count >= self.turn_after ):
                # Turn around!
                self.direction *= -1           # reverses the pixel distance
                self.pace_count = 0            # reset the pace count

            # We also should change direction if we hit the screen edge
            if ( self.rect.x <= 0 ):
                self.direction  = 1             # turn right
                self.pace_count = 0
            elif ( self.rect.x >= WINDOW_WIDTH - self.rect.width ):
                self.direction  = -1
                self.pace_count = 0


### initialisation
pygame.init()
pygame.mixer.init()
window = pygame.display.set_mode( ( WINDOW_WIDTH, WINDOW_HEIGHT ), WINDOW_SURFACE )
pygame.display.set_caption("Movement Algorithm Example")

### Sprite and Sprite Group
pos_x     = WINDOW_WIDTH//2
pos_y     = WINDOW_HEIGHT//2
pace_size = 7
enemy = Enemy( pos_x, pos_y, pace_size, "mushroom.png" )

all_sprites_group = pygame.sprite.Group()
all_sprites_group.add( enemy )


### Main Loop
clock = pygame.time.Clock()
done = False
while not done:

    # Handle user-input
    for event in pygame.event.get():
        if ( event.type == pygame.QUIT ):
            done = True
        elif ( event.type == pygame.MOUSEBUTTONUP ):
            # On mouse-click
            pass
        elif ( event.type == pygame.KEYUP ):
            pass

    # Movement keys
    #keys = pygame.key.get_pressed()
    #if ( keys[pygame.K_UP] ):
    #    print("up")

    # Update the window, but not more than 60fps
    all_sprites_group.update()
    window.fill( DARK_BLUE )
    all_sprites_group.draw( window )
    pygame.display.flip()

    # Clamp FPS
    clock.tick_busy_loop(60)

pygame.quit()