更好地通过键盘移动#

用键盘移动精灵的屏幕截图

如果玩家按下左键，精灵应该向左移动。如果球员同时左击和右击，球员应该停下来。如果玩家松开左键，保持右键不动，玩家就应该向右移动。

处理击键的较简单方法将无法正确处理此问题。此代码跟踪哪个键是按下的还是向上的，并正确处理它。

请参见高亮显示的部分。

sprite_move_keyboard_better.py#
  1"""
  2Better Move Sprite With Keyboard
  3
  4Simple program to show moving a sprite with the keyboard.
  5This is slightly better than sprite_move_keyboard.py example
  6in how it works, but also slightly more complex.
  7
  8Artwork from https://kenney.nl
  9
 10If Python and Arcade are installed, this example can be run from the command line with:
 11python -m arcade.examples.sprite_move_keyboard_better
 12"""
 13
 14import arcade
 15
 16SPRITE_SCALING = 0.5
 17
 18SCREEN_WIDTH = 800
 19SCREEN_HEIGHT = 600
 20SCREEN_TITLE = "Better Move Sprite with Keyboard Example"
 21
 22MOVEMENT_SPEED = 5
 23
 24
 25class Player(arcade.Sprite):
 26
 27    def update(self):
 28        """ Move the player """
 29        # Move player.
 30        # Remove these lines if physics engine is moving player.
 31        self.center_x += self.change_x
 32        self.center_y += self.change_y
 33
 34        # Check for out-of-bounds
 35        if self.left < 0:
 36            self.left = 0
 37        elif self.right > SCREEN_WIDTH - 1:
 38            self.right = SCREEN_WIDTH - 1
 39
 40        if self.bottom < 0:
 41            self.bottom = 0
 42        elif self.top > SCREEN_HEIGHT - 1:
 43            self.top = SCREEN_HEIGHT - 1
 44
 45
 46class MyGame(arcade.Window):
 47    """
 48    Main application class.
 49    """
 50
 51    def __init__(self, width, height, title):
 52        """
 53        Initializer
 54        """
 55
 56        # Call the parent class initializer
 57        super().__init__(width, height, title)
 58
 59        # Variables that will hold sprite lists
 60        self.player_list = None
 61
 62        # Set up the player info
 63        self.player_sprite = None
 64
 65        # Track the current state of what key is pressed
 66        self.left_pressed = False
 67        self.right_pressed = False
 68        self.up_pressed = False
 69        self.down_pressed = False
 70
 71        # Set the background color
 72        self.background_color = arcade.color.AMAZON
 73
 74    def setup(self):
 75        """ Set up the game and initialize the variables. """
 76
 77        # Sprite lists
 78        self.player_list = arcade.SpriteList()
 79
 80        # Set up the player
 81        self.player_sprite = Player(":resources:images/animated_characters/female_person/femalePerson_idle.png",
 82                                    scale=SPRITE_SCALING)
 83        self.player_sprite.center_x = 50
 84        self.player_sprite.center_y = 50
 85        self.player_list.append(self.player_sprite)
 86
 87    def on_draw(self):
 88        """ Render the screen. """
 89
 90        # Clear the screen
 91        self.clear()
 92
 93        # Draw all the sprites.
 94        self.player_list.draw()
 95
 96    def update_player_speed(self):
 97
 98        # Calculate speed based on the keys pressed
 99        self.player_sprite.change_x = 0
100        self.player_sprite.change_y = 0
101
102        if self.up_pressed and not self.down_pressed:
103            self.player_sprite.change_y = MOVEMENT_SPEED
104        elif self.down_pressed and not self.up_pressed:
105            self.player_sprite.change_y = -MOVEMENT_SPEED
106        if self.left_pressed and not self.right_pressed:
107            self.player_sprite.change_x = -MOVEMENT_SPEED
108        elif self.right_pressed and not self.left_pressed:
109            self.player_sprite.change_x = MOVEMENT_SPEED
110
111    def on_update(self, delta_time):
112        """ Movement and game logic """
113
114        # Call update to move the sprite
115        # If using a physics engine, call update player to rely on physics engine
116        # for movement, and call physics engine here.
117        self.player_list.update()
118
119    def on_key_press(self, key, modifiers):
120        """Called whenever a key is pressed. """
121
122        if key == arcade.key.UP:
123            self.up_pressed = True
124            self.update_player_speed()
125        elif key == arcade.key.DOWN:
126            self.down_pressed = True
127            self.update_player_speed()
128        elif key == arcade.key.LEFT:
129            self.left_pressed = True
130            self.update_player_speed()
131        elif key == arcade.key.RIGHT:
132            self.right_pressed = True
133            self.update_player_speed()
134
135    def on_key_release(self, key, modifiers):
136        """Called when the user releases a key. """
137
138        if key == arcade.key.UP:
139            self.up_pressed = False
140            self.update_player_speed()
141        elif key == arcade.key.DOWN:
142            self.down_pressed = False
143            self.update_player_speed()
144        elif key == arcade.key.LEFT:
145            self.left_pressed = False
146            self.update_player_speed()
147        elif key == arcade.key.RIGHT:
148            self.right_pressed = False
149            self.update_player_speed()
150
151
152def main():
153    """ Main function """
154    window = MyGame(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
155    window.setup()
156    arcade.run()
157
158
159if __name__ == "__main__":
160    main()