Move with a Scrolling Screen - Margins#
Unlike the Move with a Scrolling Screen - Centered which centers the camera on the player, this example only moves the camera if the user gets within so many pixels of the edge. It allows for a ‘box’ in the middle where the user can move around and NOT move the camera.
sprite_move_scrolling_box.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_box
8"""
9
10import random
11import arcade
12
13SPRITE_SCALING = 0.5
14
15DEFAULT_SCREEN_WIDTH = 800
16DEFAULT_SCREEN_HEIGHT = 600
17SCREEN_TITLE = "Sprite Move with Scrolling Screen Example"
18
19# How many pixels to keep as a minimum margin between the character
20# and the edge of the screen.
21VIEWPORT_MARGIN = 200
22
23# How fast the camera pans to the player. 1.0 is instant.
24CAMERA_SPEED = 0.1
25
26# How fast the character moves
27PLAYER_MOVEMENT_SPEED = 7
28
29
30class MyGame(arcade.Window):
31 """ Main application class. """
32
33 def __init__(self, width, height, title):
34 """
35 Initializer
36 """
37 super().__init__(width, height, title, resizable=True)
38
39 # Sprite lists
40 self.player_list = None
41 self.wall_list = None
42
43 # Set up the player
44 self.player_sprite = None
45
46 self.physics_engine = None
47
48 # Used in scrolling
49 self.view_bottom = 0
50 self.view_left = 0
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 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 # Set the viewport boundaries
91 # These numbers set where we have 'scrolled' to.
92 self.view_left = 0
93 self.view_bottom = 0
94
95 def on_draw(self):
96 """
97 Render the screen.
98 """
99
100 # This command has to happen before we start drawing
101 self.clear()
102
103 # Select the camera we'll use to draw all our sprites
104 self.camera_sprites.use()
105
106 # Draw all the sprites.
107 self.wall_list.draw()
108 self.player_list.draw()
109
110 # Select the (unscrolled) camera for our GUI
111 self.camera_gui.use()
112
113 # Draw the GUI
114 arcade.draw_rectangle_filled(self.width // 2, 20, self.width, 40, arcade.color.ALMOND)
115 text = f"Scroll value: ({self.camera_sprites.position[0]:5.1f}, {self.camera_sprites.position[1]:5.1f})"
116 arcade.draw_text(text, 10, 10, arcade.color.BLACK_BEAN, 20)
117
118 # Draw the box that we work to make sure the user stays inside of.
119 # This is just for illustration purposes. You'd want to remove this
120 # in your game.
121 left_boundary = VIEWPORT_MARGIN
122 right_boundary = self.width - VIEWPORT_MARGIN
123 top_boundary = self.height - VIEWPORT_MARGIN
124 bottom_boundary = VIEWPORT_MARGIN
125 arcade.draw_lrbt_rectangle_outline(left_boundary, right_boundary, bottom_boundary, top_boundary,
126 arcade.color.RED, 2)
127
128 def on_key_press(self, key, modifiers):
129 """Called whenever a key is pressed. """
130
131 if key == arcade.key.UP:
132 self.up_pressed = True
133 elif key == arcade.key.DOWN:
134 self.down_pressed = True
135 elif key == arcade.key.LEFT:
136 self.left_pressed = True
137 elif key == arcade.key.RIGHT:
138 self.right_pressed = True
139
140 def on_key_release(self, key, modifiers):
141 """Called when the user releases a key. """
142
143 if key == arcade.key.UP:
144 self.up_pressed = False
145 elif key == arcade.key.DOWN:
146 self.down_pressed = False
147 elif key == arcade.key.LEFT:
148 self.left_pressed = False
149 elif key == arcade.key.RIGHT:
150 self.right_pressed = False
151
152 def on_update(self, delta_time):
153 """ Movement and game logic """
154
155 # Calculate speed based on the keys pressed
156 self.player_sprite.change_x = 0
157 self.player_sprite.change_y = 0
158
159 if self.up_pressed and not self.down_pressed:
160 self.player_sprite.change_y = PLAYER_MOVEMENT_SPEED
161 elif self.down_pressed and not self.up_pressed:
162 self.player_sprite.change_y = -PLAYER_MOVEMENT_SPEED
163 if self.left_pressed and not self.right_pressed:
164 self.player_sprite.change_x = -PLAYER_MOVEMENT_SPEED
165 elif self.right_pressed and not self.left_pressed:
166 self.player_sprite.change_x = PLAYER_MOVEMENT_SPEED
167
168 # Call update on all sprites (The sprites don't do much in this
169 # example though.)
170 self.physics_engine.update()
171
172 # Scroll the screen to the player
173 self.scroll_to_player()
174
175 def scroll_to_player(self):
176 """
177 Scroll the window to the player.
178 This method will attempt to keep the player at least VIEWPORT_MARGIN
179 pixels away from the edge.
180
181 if CAMERA_SPEED is 1, the camera will immediately move to the desired position.
182 Anything between 0 and 1 will have the camera move to the location with a smoother
183 pan.
184 """
185
186 # --- Manage Scrolling ---
187
188 # Scroll left
189 left_boundary = self.view_left + VIEWPORT_MARGIN
190 if self.player_sprite.left < left_boundary:
191 self.view_left -= left_boundary - self.player_sprite.left
192
193 # Scroll right
194 right_boundary = self.view_left + self.width - VIEWPORT_MARGIN
195 if self.player_sprite.right > right_boundary:
196 self.view_left += self.player_sprite.right - right_boundary
197
198 # Scroll up
199 top_boundary = self.view_bottom + self.height - VIEWPORT_MARGIN
200 if self.player_sprite.top > top_boundary:
201 self.view_bottom += self.player_sprite.top - top_boundary
202
203 # Scroll down
204 bottom_boundary = self.view_bottom + VIEWPORT_MARGIN
205 if self.player_sprite.bottom < bottom_boundary:
206 self.view_bottom -= bottom_boundary - self.player_sprite.bottom
207
208 # Scroll to the proper location
209 position = self.view_left, self.view_bottom
210 self.camera_sprites.move_to(position, CAMERA_SPEED)
211
212 def on_resize(self, width: int, height: int):
213 """
214 Resize window
215 Handle the user grabbing the edge and resizing the window.
216 """
217 self.camera_sprites.resize(width, height)
218 self.camera_gui.resize(width, height)
219
220
221def main():
222 """ Main function """
223 window = MyGame(DEFAULT_SCREEN_WIDTH, DEFAULT_SCREEN_HEIGHT, SCREEN_TITLE)
224 window.setup()
225 arcade.run()
226
227
228if __name__ == "__main__":
229 main()