Sprites That Follow a Path#
follow_path.py#
1"""
2Sprite Follow Path
3
4This example has enemy sprites follow a set path.
5
6Artwork from https://kenney.nl
7
8If Python and Arcade are installed, this example can be run from the command line with:
9python -m arcade.examples.follow_path
10"""
11
12from __future__ import annotations
13
14import arcade
15import math
16
17# --- Constants ---
18SPRITE_SCALING_PLAYER = 0.5
19SPRITE_SCALING_ENEMY = 0.5
20ENEMY_SPEED = 3.0
21
22SCREEN_WIDTH = 800
23SCREEN_HEIGHT = 600
24SCREEN_TITLE = "Sprite Follow Path Simple Example"
25
26
27class Enemy(arcade.Sprite):
28 """
29 This class represents the Enemy on our screen.
30 """
31
32 def __init__(self, image, scale, position_list):
33 super().__init__(image, scale=scale)
34 self.position_list = position_list
35 self.cur_position = 0
36 self.speed = ENEMY_SPEED
37
38 def update(self):
39 """ Have a sprite follow a path """
40
41 # Where are we
42 start_x = self.center_x
43 start_y = self.center_y
44
45 # Where are we going
46 dest_x = self.position_list[self.cur_position][0]
47 dest_y = self.position_list[self.cur_position][1]
48
49 # X and Y diff between the two
50 x_diff = dest_x - start_x
51 y_diff = dest_y - start_y
52
53 # Calculate angle to get there
54 angle = math.atan2(y_diff, x_diff)
55
56 # How far are we?
57 distance = math.sqrt((self.center_x - dest_x) ** 2 + (self.center_y - dest_y) ** 2)
58
59 # How fast should we go? If we are close to our destination,
60 # lower our speed so we don't overshoot.
61 speed = min(self.speed, distance)
62
63 # Calculate vector to travel
64 change_x = math.cos(angle) * speed
65 change_y = math.sin(angle) * speed
66
67 # Update our location
68 self.center_x += change_x
69 self.center_y += change_y
70
71 # How far are we?
72 distance = math.sqrt((self.center_x - dest_x) ** 2 + (self.center_y - dest_y) ** 2)
73
74 # If we are there, head to the next point.
75 if distance <= self.speed:
76 self.cur_position += 1
77
78 # Reached the end of the list, start over.
79 if self.cur_position >= len(self.position_list):
80 self.cur_position = 0
81
82
83class MyGame(arcade.Window):
84 """ Our custom Window Class"""
85
86 def __init__(self):
87 """ Initializer """
88 # Call the parent class initializer
89 super().__init__(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
90
91 # Variables that will hold sprite lists
92 self.player_list = None
93 self.enemy_list = None
94
95 # Set up the player info
96 self.player_sprite = None
97 self.score = 0
98
99 # Don't show the mouse cursor
100 self.set_mouse_visible(False)
101
102 self.background_color = arcade.color.AMAZON
103
104 def setup(self):
105 """ Set up the game and initialize the variables. """
106
107 # Sprite lists
108 self.player_list = arcade.SpriteList()
109 self.enemy_list = arcade.SpriteList()
110
111 # Score
112 self.score = 0
113
114 # Set up the player
115 # Character image from kenney.nl
116 self.player_sprite = arcade.Sprite(
117 ":resources:images/animated_characters/female_person/femalePerson_idle.png",
118 scale=SPRITE_SCALING_PLAYER)
119 self.player_sprite.center_x = 50
120 self.player_sprite.center_y = 50
121 self.player_list.append(self.player_sprite)
122
123 # List of points the enemy will travel too.
124 position_list = [[50, 50],
125 [700, 50],
126 [700, 500],
127 [50, 500]]
128
129 # Create the enemy
130 enemy = Enemy(":resources:images/animated_characters/robot/robot_idle.png",
131 SPRITE_SCALING_ENEMY,
132 position_list)
133
134 # Set initial location of the enemy at the first point
135 enemy.center_x = position_list[0][0]
136 enemy.center_x = position_list[0][1]
137
138 # Add the enemy to the enemy list
139 self.enemy_list.append(enemy)
140
141 def on_draw(self):
142 """ Draw everything """
143 self.clear()
144 self.enemy_list.draw()
145 self.player_list.draw()
146
147 def on_mouse_motion(self, x, y, dx, dy):
148 """ Handle Mouse Motion """
149
150 # Move the center of the player sprite to match the mouse x, y
151 self.player_sprite.center_x = x
152 self.player_sprite.center_y = y
153
154 def on_update(self, delta_time):
155 """ Movement and game logic """
156 self.enemy_list.update()
157
158
159def main():
160 """ Main function """
161 window = MyGame()
162 window.setup()
163 arcade.run()
164
165
166if __name__ == "__main__":
167 main()