Camera Shake#

Screen shot of using a scrolling window

You can cause the camera to shake, as this example does when the player encounters a bomb. See the highlighted lines below.

sprite_move_scrolling_shake.py#
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
"""
Scroll around a large screen.

Artwork from https://kenney.nl

If Python and Arcade are installed, this example can be run from the command line with:
python -m arcade.examples.sprite_move_scrolling
"""

import random
import math
import arcade
from pyglet.math import Vec2

SPRITE_SCALING = 0.5

DEFAULT_SCREEN_WIDTH = 800
DEFAULT_SCREEN_HEIGHT = 600
SCREEN_TITLE = "Camera Shake Example"

# How many pixels to keep as a minimum margin between the character
# and the edge of the screen.
VIEWPORT_MARGIN = 220

# How fast the camera pans to the player. 1.0 is instant.
CAMERA_SPEED = 0.1

# How fast the character moves
PLAYER_MOVEMENT_SPEED = 7

BOMB_COUNT = 50
PLAYING_FIELD_WIDTH = 1600
PLAYING_FIELD_HEIGHT = 1600


class MyGame(arcade.Window):
    """ Main application class. """

    def __init__(self, width, height, title):
        """
        Initializer
        """
        super().__init__(width, height, title, resizable=True)

        # Sprite lists
        self.player_list = None
        self.wall_list = None
        self.bomb_list = None

        # Set up the player
        self.player_sprite = None

        # Physics engine so we don't run into walls.
        self.physics_engine = None

        # Create the cameras. One for the GUI, one for the sprites.
        # We scroll the 'sprite world' but not the GUI.
        self.camera_sprites = arcade.Camera(DEFAULT_SCREEN_WIDTH, DEFAULT_SCREEN_HEIGHT)
        self.camera_gui = arcade.Camera(DEFAULT_SCREEN_WIDTH, DEFAULT_SCREEN_HEIGHT)

        self.explosion_sound = arcade.load_sound(":resources:sounds/explosion1.wav")

    def setup(self):
        """ Set up the game and initialize the variables. """

        # Sprite lists
        self.player_list = arcade.SpriteList()
        self.wall_list = arcade.SpriteList()
        self.bomb_list = arcade.SpriteList()

        # Set up the player
        self.player_sprite = arcade.Sprite(":resources:images/animated_characters/female_person/femalePerson_idle.png",
                                           scale=0.4)
        self.player_sprite.center_x = 512
        self.player_sprite.center_y = 512
        self.player_list.append(self.player_sprite)

        # -- Set up several columns of walls
        for x in range(200, PLAYING_FIELD_WIDTH, 210):
            for y in range(0, PLAYING_FIELD_HEIGHT, 64):
                # Randomly skip a box so the player can find a way through
                if random.randrange(5) > 0:
                    wall = arcade.Sprite(":resources:images/tiles/grassCenter.png", SPRITE_SCALING)
                    wall.center_x = x
                    wall.center_y = y
                    self.wall_list.append(wall)

        for i in range(BOMB_COUNT):
            bomb = arcade.Sprite(":resources:images/tiles/bomb.png", 0.25)
            placed = False
            while not placed:
                bomb.center_x = random.randrange(PLAYING_FIELD_WIDTH)
                bomb.center_y = random.randrange(PLAYING_FIELD_HEIGHT)
                if not arcade.check_for_collision_with_list(bomb, self.wall_list):
                    placed = True
            self.bomb_list.append(bomb)

        self.physics_engine = arcade.PhysicsEngineSimple(self.player_sprite, self.wall_list)

        # Set the background color
        arcade.set_background_color(arcade.color.AMAZON)

    def on_draw(self):
        """
        Render the screen.
        """

        # This command has to happen before we start drawing
        self.clear()

        # Select the camera we'll use to draw all our sprites
        self.camera_sprites.use()

        # Draw all the sprites.
        self.wall_list.draw()
        self.bomb_list.draw()
        self.player_list.draw()

    def on_key_press(self, key, modifiers):
        """Called whenever a key is pressed. """

        if key == arcade.key.UP:
            self.player_sprite.change_y = PLAYER_MOVEMENT_SPEED
        elif key == arcade.key.DOWN:
            self.player_sprite.change_y = -PLAYER_MOVEMENT_SPEED
        elif key == arcade.key.LEFT:
            self.player_sprite.change_x = -PLAYER_MOVEMENT_SPEED
        elif key == arcade.key.RIGHT:
            self.player_sprite.change_x = PLAYER_MOVEMENT_SPEED

    def on_key_release(self, key, modifiers):
        """Called when the user releases a key. """

        if key == arcade.key.UP or key == arcade.key.DOWN:
            self.player_sprite.change_y = 0
        elif key == arcade.key.LEFT or key == arcade.key.RIGHT:
            self.player_sprite.change_x = 0

    def on_update(self, delta_time):
        """ Movement and game logic """

        # Call update on all sprites (The sprites don't do much in this
        # example though.)
        self.physics_engine.update()

        # Scroll the screen to the player
        self.scroll_to_player()

        hit_list = arcade.check_for_collision_with_list(self.player_sprite, self.bomb_list)
        for bomb in hit_list:
            # Remove the bomb and go 'boom'
            bomb.remove_from_sprite_lists()
            self.explosion_sound.play()

            # --- Shake the camera ---
            # Pick a random direction
            shake_direction = random.random() * 2 * math.pi
            # How 'far' to shake
            shake_amplitude = 10
            # Calculate a vector based on that
            shake_vector = Vec2(
                math.cos(shake_direction) * shake_amplitude,
                math.sin(shake_direction) * shake_amplitude
            )
            # Frequency of the shake
            shake_speed = 1.5
            # How fast to damp the shake
            shake_damping = 0.9
            # Do the shake
            self.camera_sprites.shake(shake_vector,
                                      speed=shake_speed,
                                      damping=shake_damping)

    def scroll_to_player(self):
        """
        Scroll the window to the player.

        if CAMERA_SPEED is 1, the camera will immediately move to the desired position.
        Anything between 0 and 1 will have the camera move to the location with a smoother
        pan.
        """

        position = Vec2(
            self.player_sprite.center_x - self.width / 2,
            self.player_sprite.center_y - self.height / 2
        )
        self.camera_sprites.move_to(position, CAMERA_SPEED)

    def on_resize(self, width, height):
        """
        Resize window
        Handle the user grabbing the edge and resizing the window.
        """
        self.camera_sprites.resize(int(width), int(height))
        self.camera_gui.resize(int(width), int(height))


def main():
    """ Main function """
    window = MyGame(DEFAULT_SCREEN_WIDTH, DEFAULT_SCREEN_HEIGHT, SCREEN_TITLE)
    window.setup()
    arcade.run()


if __name__ == "__main__":
    main()