Multiple Bouncing Balls¶
bouncing_balls.py¶
1"""
2Bounce balls on the screen.
3Spawn a new ball for each mouse-click.
4
5If Python and Arcade are installed, this example can be run from the command line with:
6python -m arcade.examples.bouncing_balls
7"""
8
9import arcade
10import random
11
12# --- Set up the constants
13
14# Size of the screen
15SCREEN_WIDTH = 600
16SCREEN_HEIGHT = 600
17SCREEN_TITLE = "Bouncing Balls Example"
18
19
20class Ball:
21 """
22 Class to keep track of a ball's location and vector.
23 """
24 def __init__(self):
25 self.x = 0
26 self.y = 0
27 self.change_x = 0
28 self.change_y = 0
29 self.size = 0
30 self.color = None
31
32
33def make_ball():
34 """
35 Function to make a new, random ball.
36 """
37 ball = Ball()
38
39 # Size of the ball
40 ball.size = random.randrange(10, 30)
41
42 # Starting position of the ball.
43 # Take into account the ball size so we don't spawn on the edge.
44 ball.x = random.randrange(ball.size, SCREEN_WIDTH - ball.size)
45 ball.y = random.randrange(ball.size, SCREEN_HEIGHT - ball.size)
46
47 # Speed and direction of rectangle
48 ball.change_x = random.randrange(-2, 3)
49 ball.change_y = random.randrange(-2, 3)
50
51 # Color
52 ball.color = (random.randrange(256), random.randrange(256), random.randrange(256))
53
54 return ball
55
56
57class MyGame(arcade.Window):
58 """ Main application class. """
59
60 def __init__(self):
61 super().__init__(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
62 self.ball_list = []
63 ball = make_ball()
64 self.ball_list.append(ball)
65
66 def on_draw(self):
67 """
68 Render the screen.
69 """
70
71 # This command has to happen before we start drawing
72 arcade.start_render()
73
74 for ball in self.ball_list:
75 arcade.draw_circle_filled(ball.x, ball.y, ball.size, ball.color)
76
77 # Put the text on the screen.
78 output = "Balls: {}".format(len(self.ball_list))
79 arcade.draw_text(output, 10, 20, arcade.color.WHITE, 14)
80
81 def on_update(self, delta_time):
82 """ Movement and game logic """
83 for ball in self.ball_list:
84 ball.x += ball.change_x
85 ball.y += ball.change_y
86
87 if ball.x < ball.size:
88 ball.change_x *= -1
89
90 if ball.y < ball.size:
91 ball.change_y *= -1
92
93 if ball.x > SCREEN_WIDTH - ball.size:
94 ball.change_x *= -1
95
96 if ball.y > SCREEN_HEIGHT - ball.size:
97 ball.change_y *= -1
98
99 def on_mouse_press(self, x, y, button, modifiers):
100 """
101 Called whenever the mouse button is clicked.
102 """
103 ball = make_ball()
104 self.ball_list.append(ball)
105
106
107def main():
108 MyGame()
109 arcade.run()
110
111
112if __name__ == "__main__":
113 main()