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
10from __future__ import annotations
11
12import random
13import arcade
14
15SPRITE_SCALING = 0.5
16
17DEFAULT_SCREEN_WIDTH = 800
18DEFAULT_SCREEN_HEIGHT = 600
19SCREEN_TITLE = "Sprite Move with Scrolling Screen Example"
20
21# How many pixels to keep as a minimum margin between the character
22# and the edge of the screen.
23VIEWPORT_MARGIN = 200
24
25# How fast the camera pans to the player. 1.0 is instant.
26CAMERA_SPEED = 0.1
27
28# How fast the character moves
29PLAYER_MOVEMENT_SPEED = 7
30
31
32class MyGame(arcade.Window):
33 """ Main application class. """
34
35 def __init__(self, width, height, title):
36 """
37 Initializer
38 """
39 super().__init__(width, height, title, resizable=True)
40
41 # Sprite lists
42 self.player_list = None
43 self.wall_list = None
44
45 # Set up the player
46 self.player_sprite = None
47
48 self.physics_engine = None
49
50 # Used in scrolling
51 self.view_bottom = 0
52 self.view_left = 0
53
54 # Track the current state of what key is pressed
55 self.left_pressed = False
56 self.right_pressed = False
57 self.up_pressed = False
58 self.down_pressed = False
59
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 # Set the viewport boundaries
93 # These numbers set where we have 'scrolled' to.
94 self.view_left = 0
95 self.view_bottom = 0
96
97 def on_draw(self):
98 """
99 Render the screen.
100 """
101
102 # This command has to happen before we start drawing
103 self.clear()
104
105 # Select the camera we'll use to draw all our sprites
106 self.camera_sprites.use()
107
108 # Draw all the sprites.
109 self.wall_list.draw()
110 self.player_list.draw()
111
112 # Select the (unscrolled) camera for our GUI
113 self.camera_gui.use()
114
115 # Draw the GUI
116 arcade.draw_rectangle_filled(self.width // 2, 20, self.width, 40, arcade.color.ALMOND)
117 text = f"Scroll value: ({self.camera_sprites.position[0]:5.1f}, {self.camera_sprites.position[1]:5.1f})"
118 arcade.draw_text(text, 10, 10, arcade.color.BLACK_BEAN, 20)
119
120 # Draw the box that we work to make sure the user stays inside of.
121 # This is just for illustration purposes. You'd want to remove this
122 # in your game.
123 left_boundary = VIEWPORT_MARGIN
124 right_boundary = self.width - VIEWPORT_MARGIN
125 top_boundary = self.height - VIEWPORT_MARGIN
126 bottom_boundary = VIEWPORT_MARGIN
127 arcade.draw_lrbt_rectangle_outline(left_boundary, right_boundary, bottom_boundary, top_boundary,
128 arcade.color.RED, 2)
129
130 def on_key_press(self, key, modifiers):
131 """Called whenever a key is pressed. """
132
133 if key == arcade.key.UP:
134 self.up_pressed = True
135 elif key == arcade.key.DOWN:
136 self.down_pressed = True
137 elif key == arcade.key.LEFT:
138 self.left_pressed = True
139 elif key == arcade.key.RIGHT:
140 self.right_pressed = True
141
142 def on_key_release(self, key, modifiers):
143 """Called when the user releases a key. """
144
145 if key == arcade.key.UP:
146 self.up_pressed = False
147 elif key == arcade.key.DOWN:
148 self.down_pressed = False
149 elif key == arcade.key.LEFT:
150 self.left_pressed = False
151 elif key == arcade.key.RIGHT:
152 self.right_pressed = False
153
154 def on_update(self, delta_time):
155 """ Movement and game logic """
156
157 # Calculate speed based on the keys pressed
158 self.player_sprite.change_x = 0
159 self.player_sprite.change_y = 0
160
161 if self.up_pressed and not self.down_pressed:
162 self.player_sprite.change_y = PLAYER_MOVEMENT_SPEED
163 elif self.down_pressed and not self.up_pressed:
164 self.player_sprite.change_y = -PLAYER_MOVEMENT_SPEED
165 if self.left_pressed and not self.right_pressed:
166 self.player_sprite.change_x = -PLAYER_MOVEMENT_SPEED
167 elif self.right_pressed and not self.left_pressed:
168 self.player_sprite.change_x = PLAYER_MOVEMENT_SPEED
169
170 # Call update on all sprites (The sprites don't do much in this
171 # example though.)
172 self.physics_engine.update()
173
174 # Scroll the screen to the player
175 self.scroll_to_player()
176
177 def scroll_to_player(self):
178 """
179 Scroll the window to the player.
180 This method will attempt to keep the player at least VIEWPORT_MARGIN
181 pixels away from the edge.
182
183 if CAMERA_SPEED is 1, the camera will immediately move to the desired position.
184 Anything between 0 and 1 will have the camera move to the location with a smoother
185 pan.
186 """
187
188 # --- Manage Scrolling ---
189
190 # Scroll left
191 left_boundary = self.view_left + VIEWPORT_MARGIN
192 if self.player_sprite.left < left_boundary:
193 self.view_left -= left_boundary - self.player_sprite.left
194
195 # Scroll right
196 right_boundary = self.view_left + self.width - VIEWPORT_MARGIN
197 if self.player_sprite.right > right_boundary:
198 self.view_left += self.player_sprite.right - right_boundary
199
200 # Scroll up
201 top_boundary = self.view_bottom + self.height - VIEWPORT_MARGIN
202 if self.player_sprite.top > top_boundary:
203 self.view_bottom += self.player_sprite.top - top_boundary
204
205 # Scroll down
206 bottom_boundary = self.view_bottom + VIEWPORT_MARGIN
207 if self.player_sprite.bottom < bottom_boundary:
208 self.view_bottom -= bottom_boundary - self.player_sprite.bottom
209
210 # Scroll to the proper location
211 position = self.view_left, self.view_bottom
212 self.camera_sprites.move_to(position, CAMERA_SPEED)
213
214 def on_resize(self, width: int, height: int):
215 """
216 Resize window
217 Handle the user grabbing the edge and resizing the window.
218 """
219 self.camera_sprites.resize(width, height)
220 self.camera_gui.resize(width, height)
221
222
223def main():
224 """ Main function """
225 window = MyGame(DEFAULT_SCREEN_WIDTH, DEFAULT_SCREEN_HEIGHT, SCREEN_TITLE)
226 window.setup()
227 arcade.run()
228
229
230if __name__ == "__main__":
231 main()