让敌人定期射击#
让敌人射杀每一个 x 秒比随机拍摄要复杂一些，如所示 让敌人随意射击 。这是因为我们需要跟踪我们拍摄的频率，以及距离我们上次拍摄有多长时间。
此示例使用自定义子类 EnemySprite 。额外的属性允许我们跟踪周期计时。有关此示例的特定内容，请参阅突出显示的行。
sprite_bullets_periodic.py#
1"""
2Show how to have enemies shoot bullets at regular intervals.
3
4If Python and Arcade are installed, this example can be run from the command line with:
5python -m arcade.examples.sprite_bullets_periodic
6"""
7import arcade
8
9SCREEN_WIDTH = 800
10SCREEN_HEIGHT = 600
11SCREEN_TITLE = "Sprites and Periodic Bullets Example"
12
13
14class EnemySprite(arcade.Sprite):
15 """ Enemy ship class that tracks how long it has been since firing. """
16
17 def __init__(self, image_file, scale, bullet_list, time_between_firing):
18 """ Set up the enemy """
19 super().__init__(image_file, scale=scale)
20
21 # How long has it been since we last fired?
22 self.time_since_last_firing = 0.0
23
24 # How often do we fire?
25 self.time_between_firing = time_between_firing
26
27 # When we fire, what list tracks the bullets?
28 self.bullet_list = bullet_list
29
30 def on_update(self, delta_time: float = 1 / 60):
31 """ Update this sprite. """
32
33 # Track time since we last fired
34 self.time_since_last_firing += delta_time
35
36 # If we are past the firing time, then fire
37 if self.time_since_last_firing >= self.time_between_firing:
38
39 # Reset timer
40 self.time_since_last_firing = 0
41
42 # Fire the bullet
43 bullet = arcade.Sprite(":resources:images/space_shooter/laserBlue01.png")
44 bullet.center_x = self.center_x
45 bullet.angle = 90
46 bullet.top = self.bottom
47 bullet.change_y = -2
48 self.bullet_list.append(bullet)
49
50
51class MyGame(arcade.Window):
52 """ Main application class """
53
54 def __init__(self):
55 super().__init__(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
56
57 self.background_color = arcade.color.BLACK
58
59 self.player = None
60 self.player_list = None
61 self.enemy_list = None
62 self.bullet_list = None
63
64 def setup(self):
65 """ Set up the variables for the game. """
66
67 self.player_list = arcade.SpriteList()
68 self.enemy_list = arcade.SpriteList()
69 self.bullet_list = arcade.SpriteList()
70
71 # Add player ship
72 self.player = arcade.Sprite(":resources:images/space_shooter/playerShip1_orange.png", scale=0.5)
73 self.player_list.append(self.player)
74
75 # Add top-left enemy ship
76 enemy = EnemySprite(":resources:images/space_shooter/playerShip1_green.png",
77 scale=0.5,
78 bullet_list=self.bullet_list,
79 time_between_firing=2.0)
80 enemy.center_x = 120
81 enemy.center_y = SCREEN_HEIGHT - enemy.height
82 enemy.angle = 180
83 self.enemy_list.append(enemy)
84
85 # Add top-right enemy ship
86 enemy = EnemySprite(":resources:images/space_shooter/playerShip1_green.png",
87 scale=0.5,
88 bullet_list=self.bullet_list,
89 time_between_firing=1.0)
90 enemy.center_x = SCREEN_WIDTH - 120
91 enemy.center_y = SCREEN_HEIGHT - enemy.height
92 enemy.angle = 180
93 self.enemy_list.append(enemy)
94
95 def on_draw(self):
96 """Render the screen. """
97
98 self.clear()
99
100 self.enemy_list.draw()
101 self.bullet_list.draw()
102 self.player_list.draw()
103
104 def on_update(self, delta_time):
105 """ All the logic to move, and the game logic goes here. """
106
107 # Call on_update for each enemy in the list
108 self.enemy_list.on_update(delta_time)
109
110 # Get rid of the bullet when it flies off-screen
111 for bullet in self.bullet_list:
112 if bullet.top < 0:
113 bullet.remove_from_sprite_lists()
114
115 self.bullet_list.update()
116
117 def on_mouse_motion(self, x, y, delta_x, delta_y):
118 """
119 Called whenever the mouse moves.
120 """
121 self.player.center_x = x
122 self.player.center_y = 20
123
124
125def main():
126 """ Run the game """
127 window = MyGame()
128 window.setup()
129 arcade.run()
130
131
132if __name__ == "__main__":
133 main()