Move with a Scrolling Screen - Centered#
Using a arcade.Camera, a program can easily scroll around a larger
“world” while only showing part of it on the screen.
If you are displaying a GUI or some other items that should NOT scroll, you’ll need two cameras. One that shows the unscrolled GUI, and one that shows the scrolled sprites.
See also Move with a Scrolling Screen - Margins.
sprite_move_scrolling.py#
1"""
2Scroll around a large screen.
3
4Artwork from https://kenney.nl
5
6If Python and Arcade are installed, this example can be run from the command line with:
7python -m arcade.examples.sprite_move_scrolling
8"""
9
10import random
11import arcade
12from pyglet.math import Vec2
13
14SPRITE_SCALING = 0.5
15
16DEFAULT_SCREEN_WIDTH = 800
17DEFAULT_SCREEN_HEIGHT = 600
18SCREEN_TITLE = "Sprite Move with Scrolling Screen Example"
19
20# How many pixels to keep as a minimum margin between the character
21# and the edge of the screen.
22VIEWPORT_MARGIN = 220
23
24# How fast the camera pans to the player. 1.0 is instant.
25CAMERA_SPEED = 0.1
26
27# How fast the character moves
28PLAYER_MOVEMENT_SPEED = 7
29
30
31class MyGame(arcade.Window):
32 """ Main application class. """
33
34 def __init__(self, width, height, title):
35 """
36 Initializer
37 """
38 super().__init__(width, height, title, resizable=True)
39
40 # Sprite lists
41 self.player_list = None
42 self.wall_list = None
43
44 # Set up the player
45 self.player_sprite = None
46
47 # Physics engine so we don't run into walls.
48 self.physics_engine = None
49
50 # Track the current state of what key is pressed
51 self.left_pressed = False
52 self.right_pressed = False
53 self.up_pressed = False
54 self.down_pressed = False
55
56 # Create the cameras. One for the GUI, one for the sprites.
57 # We scroll the 'sprite world' but not the GUI.
58 self.camera_sprites = arcade.SimpleCamera()
59 self.camera_gui = arcade.SimpleCamera()
60
61 def setup(self):
62 """ Set up the game and initialize the variables. """
63
64 # Sprite lists
65 self.player_list = arcade.SpriteList()
66 self.wall_list = arcade.SpriteList()
67
68 # Set up the player
69 self.player_sprite = arcade.Sprite(":resources:images/animated_characters/female_person/femalePerson_idle.png",
70 scale=0.4)
71 self.player_sprite.center_x = 256
72 self.player_sprite.center_y = 512
73 self.player_list.append(self.player_sprite)
74
75 # -- Set up several columns of walls
76 for x in range(200, 1650, 210):
77 for y in range(0, 1600, 64):
78 # Randomly skip a box so the player can find a way through
79 if random.randrange(5) > 0:
80 wall = arcade.Sprite(":resources:images/tiles/grassCenter.png", scale=SPRITE_SCALING)
81 wall.center_x = x
82 wall.center_y = y
83 self.wall_list.append(wall)
84
85 self.physics_engine = arcade.PhysicsEngineSimple(self.player_sprite, self.wall_list)
86
87 # Set the background color
88 self.background_color = arcade.color.AMAZON
89
90 def on_draw(self):
91 """ Render the screen. """
92
93 # This command has to happen before we start drawing
94 self.clear()
95
96 # Select the camera we'll use to draw all our sprites
97 self.camera_sprites.use()
98
99 # Draw all the sprites.
100 self.wall_list.draw()
101 self.player_list.draw()
102
103 # Select the (unscrolled) camera for our GUI
104 self.camera_gui.use()
105
106 # Draw the GUI
107 arcade.draw_rectangle_filled(self.width // 2,
108 20,
109 self.width,
110 40,
111 arcade.color.ALMOND)
112 text = f"Scroll value: ({self.camera_sprites.position[0]:5.1f}, " \
113 f"{self.camera_sprites.position[1]:5.1f})"
114 arcade.draw_text(text, 10, 10, arcade.color.BLACK_BEAN, 20)
115
116 def on_key_press(self, key, modifiers):
117 """Called whenever a key is pressed. """
118
119 if key == arcade.key.UP:
120 self.up_pressed = True
121 elif key == arcade.key.DOWN:
122 self.down_pressed = True
123 elif key == arcade.key.LEFT:
124 self.left_pressed = True
125 elif key == arcade.key.RIGHT:
126 self.right_pressed = True
127
128 def on_key_release(self, key, modifiers):
129 """Called when the user releases a key. """
130
131 if key == arcade.key.UP:
132 self.up_pressed = False
133 elif key == arcade.key.DOWN:
134 self.down_pressed = False
135 elif key == arcade.key.LEFT:
136 self.left_pressed = False
137 elif key == arcade.key.RIGHT:
138 self.right_pressed = False
139
140 def on_update(self, delta_time):
141 """ Movement and game logic """
142
143 # Calculate speed based on the keys pressed
144 self.player_sprite.change_x = 0
145 self.player_sprite.change_y = 0
146
147 if self.up_pressed and not self.down_pressed:
148 self.player_sprite.change_y = PLAYER_MOVEMENT_SPEED
149 elif self.down_pressed and not self.up_pressed:
150 self.player_sprite.change_y = -PLAYER_MOVEMENT_SPEED
151 if self.left_pressed and not self.right_pressed:
152 self.player_sprite.change_x = -PLAYER_MOVEMENT_SPEED
153 elif self.right_pressed and not self.left_pressed:
154 self.player_sprite.change_x = PLAYER_MOVEMENT_SPEED
155
156 # Call update on all sprites (The sprites don't do much in this
157 # example though.)
158 self.physics_engine.update()
159
160 # Scroll the screen to the player
161 self.scroll_to_player()
162
163 def scroll_to_player(self):
164 """
165 Scroll the window to the player.
166
167 if CAMERA_SPEED is 1, the camera will immediately move to the desired position.
168 Anything between 0 and 1 will have the camera move to the location with a smoother
169 pan.
170 """
171
172 position = Vec2(self.player_sprite.center_x - self.width / 2,
173 self.player_sprite.center_y - self.height / 2)
174 self.camera_sprites.move_to(position, CAMERA_SPEED)
175
176 def on_resize(self, width: int, height: int):
177 """
178 Resize window
179 Handle the user grabbing the edge and resizing the window.
180 """
181 self.camera_sprites.resize(width, height)
182 self.camera_gui.resize(width, height)
183
184
185def main():
186 """ Main function """
187 window = MyGame(DEFAULT_SCREEN_WIDTH, DEFAULT_SCREEN_HEIGHT, SCREEN_TITLE)
188 window.setup()
189 arcade.run()
190
191
192if __name__ == "__main__":
193 main()