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
10from __future__ import annotations
11
12import random
13import arcade
14from pyglet.math import Vec2
15
16SPRITE_SCALING = 0.5
17
18DEFAULT_SCREEN_WIDTH = 800
19DEFAULT_SCREEN_HEIGHT = 600
20SCREEN_TITLE = "Sprite Move with Scrolling Screen Example"
21
22# How many pixels to keep as a minimum margin between the character
23# and the edge of the screen.
24VIEWPORT_MARGIN = 220
25
26# How fast the camera pans to the player. 1.0 is instant.
27CAMERA_SPEED = 0.1
28
29# How fast the character moves
30PLAYER_MOVEMENT_SPEED = 7
31
32
33class MyGame(arcade.Window):
34 """ Main application class. """
35
36 def __init__(self, width, height, title):
37 """
38 Initializer
39 """
40 super().__init__(width, height, title, resizable=True)
41
42 # Sprite lists
43 self.player_list = None
44 self.wall_list = None
45
46 # Set up the player
47 self.player_sprite = None
48
49 # Physics engine so we don't run into walls.
50 self.physics_engine = None
51
52 # Track the current state of what key is pressed
53 self.left_pressed = False
54 self.right_pressed = False
55 self.up_pressed = False
56 self.down_pressed = False
57
58 # Create the cameras. One for the GUI, one for the sprites.
59 # We scroll the 'sprite world' but not the GUI.
60 self.camera_sprites = arcade.SimpleCamera()
61 self.camera_gui = arcade.SimpleCamera()
62
63 def setup(self):
64 """ Set up the game and initialize the variables. """
65
66 # Sprite lists
67 self.player_list = arcade.SpriteList()
68 self.wall_list = arcade.SpriteList()
69
70 # Set up the player
71 self.player_sprite = arcade.Sprite(":resources:images/animated_characters/female_person/femalePerson_idle.png",
72 scale=0.4)
73 self.player_sprite.center_x = 256
74 self.player_sprite.center_y = 512
75 self.player_list.append(self.player_sprite)
76
77 # -- Set up several columns of walls
78 for x in range(200, 1650, 210):
79 for y in range(0, 1600, 64):
80 # Randomly skip a box so the player can find a way through
81 if random.randrange(5) > 0:
82 wall = arcade.Sprite(":resources:images/tiles/grassCenter.png", scale=SPRITE_SCALING)
83 wall.center_x = x
84 wall.center_y = y
85 self.wall_list.append(wall)
86
87 self.physics_engine = arcade.PhysicsEngineSimple(self.player_sprite, self.wall_list)
88
89 # Set the background color
90 self.background_color = arcade.color.AMAZON
91
92 def on_draw(self):
93 """ Render the screen. """
94
95 # This command has to happen before we start drawing
96 self.clear()
97
98 # Select the camera we'll use to draw all our sprites
99 self.camera_sprites.use()
100
101 # Draw all the sprites.
102 self.wall_list.draw()
103 self.player_list.draw()
104
105 # Select the (unscrolled) camera for our GUI
106 self.camera_gui.use()
107
108 # Draw the GUI
109 arcade.draw_rectangle_filled(self.width // 2,
110 20,
111 self.width,
112 40,
113 arcade.color.ALMOND)
114 text = f"Scroll value: ({self.camera_sprites.position[0]:5.1f}, " \
115 f"{self.camera_sprites.position[1]:5.1f})"
116 arcade.draw_text(text, 10, 10, arcade.color.BLACK_BEAN, 20)
117
118 def on_key_press(self, key, modifiers):
119 """Called whenever a key is pressed. """
120
121 if key == arcade.key.UP:
122 self.up_pressed = True
123 elif key == arcade.key.DOWN:
124 self.down_pressed = True
125 elif key == arcade.key.LEFT:
126 self.left_pressed = True
127 elif key == arcade.key.RIGHT:
128 self.right_pressed = True
129
130 def on_key_release(self, key, modifiers):
131 """Called when the user releases a key. """
132
133 if key == arcade.key.UP:
134 self.up_pressed = False
135 elif key == arcade.key.DOWN:
136 self.down_pressed = False
137 elif key == arcade.key.LEFT:
138 self.left_pressed = False
139 elif key == arcade.key.RIGHT:
140 self.right_pressed = False
141
142 def on_update(self, delta_time):
143 """ Movement and game logic """
144
145 # Calculate speed based on the keys pressed
146 self.player_sprite.change_x = 0
147 self.player_sprite.change_y = 0
148
149 if self.up_pressed and not self.down_pressed:
150 self.player_sprite.change_y = PLAYER_MOVEMENT_SPEED
151 elif self.down_pressed and not self.up_pressed:
152 self.player_sprite.change_y = -PLAYER_MOVEMENT_SPEED
153 if self.left_pressed and not self.right_pressed:
154 self.player_sprite.change_x = -PLAYER_MOVEMENT_SPEED
155 elif self.right_pressed and not self.left_pressed:
156 self.player_sprite.change_x = PLAYER_MOVEMENT_SPEED
157
158 # Call update on all sprites (The sprites don't do much in this
159 # example though.)
160 self.physics_engine.update()
161
162 # Scroll the screen to the player
163 self.scroll_to_player()
164
165 def scroll_to_player(self):
166 """
167 Scroll the window to the player.
168
169 if CAMERA_SPEED is 1, the camera will immediately move to the desired position.
170 Anything between 0 and 1 will have the camera move to the location with a smoother
171 pan.
172 """
173
174 position = Vec2(self.player_sprite.center_x - self.width / 2,
175 self.player_sprite.center_y - self.height / 2)
176 self.camera_sprites.move_to(position, CAMERA_SPEED)
177
178 def on_resize(self, width: int, height: int):
179 """
180 Resize window
181 Handle the user grabbing the edge and resizing the window.
182 """
183 self.camera_sprites.resize(width, height)
184 self.camera_gui.resize(width, height)
185
186
187def main():
188 """ Main function """
189 window = MyGame(DEFAULT_SCREEN_WIDTH, DEFAULT_SCREEN_HEIGHT, SCREEN_TITLE)
190 window.setup()
191 arcade.run()
192
193
194if __name__ == "__main__":
195 main()