# Sprites That Follow The Player 2¶

sprite_follow_simple_2.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``` ```""" Sprite Follow Player 2 This calculates a 'vector' towards the player and randomly updates it based on the player's location. This is a bit more complex, but more interesting way of following the player. Artwork from http://kenney.nl If Python and Arcade are installed, this example can be run from the command line with: python -m arcade.examples.sprite_follow_simple_2 """ import random import arcade import math import os # --- Constants --- SPRITE_SCALING_PLAYER = 0.5 SPRITE_SCALING_COIN = 0.2 COIN_COUNT = 5 COIN_SPEED = 0.5 SCREEN_WIDTH = 800 SCREEN_HEIGHT = 600 SCREEN_TITLE = "Sprite Follow Player Simple Example 2" SPRITE_SPEED = 0.5 class Coin(arcade.Sprite): """ This class represents the coins on our screen. It is a child class of the arcade library's "Sprite" class. """ def follow_sprite(self, player_sprite): """ This function will move the current sprite towards whatever other sprite is specified as a parameter. We use the 'min' function here to get the sprite to line up with the target sprite, and not jump around if the sprite is not off an exact multiple of SPRITE_SPEED. """ self.center_x += self.change_x self.center_y += self.change_y # Random 1 in 100 chance that we'll change from our old direction and # then re-aim toward the player if random.randrange(100) == 0: start_x = self.center_x start_y = self.center_y # Get the destination location for the bullet dest_x = player_sprite.center_x dest_y = player_sprite.center_y # Do math to calculate how to get the bullet to the destination. # Calculation the angle in radians between the start points # and end points. This is the angle the bullet will travel. x_diff = dest_x - start_x y_diff = dest_y - start_y angle = math.atan2(y_diff, x_diff) # Taking into account the angle, calculate our change_x # and change_y. Velocity is how fast the bullet travels. self.change_x = math.cos(angle) * COIN_SPEED self.change_y = math.sin(angle) * COIN_SPEED class MyGame(arcade.Window): """ Our custom Window Class""" def __init__(self): """ Initializer """ # Call the parent class initializer super().__init__(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE) # Set the working directory (where we expect to find files) to the same # directory this .py file is in. You can leave this out of your own # code, but it is needed to easily run the examples using "python -m" # as mentioned at the top of this program. file_path = os.path.dirname(os.path.abspath(__file__)) os.chdir(file_path) # Variables that will hold sprite lists self.player_list = None self.coin_list = None # Set up the player info self.player_sprite = None self.score = 0 # Don't show the mouse cursor self.set_mouse_visible(False) arcade.set_background_color(arcade.color.AMAZON) def setup(self): """ Set up the game and initialize the variables. """ # Sprite lists self.player_list = arcade.SpriteList() self.coin_list = arcade.SpriteList() # Score self.score = 0 # Set up the player # Character image from kenney.nl self.player_sprite = arcade.Sprite(":resources:images/animated_characters/female_person/femalePerson_idle.png", SPRITE_SCALING_PLAYER) self.player_sprite.center_x = 50 self.player_sprite.center_y = 50 self.player_list.append(self.player_sprite) # Create the coins for i in range(COIN_COUNT): # Create the coin instance # Coin image from kenney.nl coin = Coin(":resources:images/items/coinGold.png", SPRITE_SCALING_COIN) # Position the coin coin.center_x = random.randrange(SCREEN_WIDTH) coin.center_y = random.randrange(SCREEN_HEIGHT) # Add the coin to the lists self.coin_list.append(coin) def on_draw(self): """ Draw everything """ arcade.start_render() self.coin_list.draw() self.player_list.draw() # Put the text on the screen. output = f"Score: {self.score}" arcade.draw_text(output, 10, 20, arcade.color.WHITE, 14) def on_mouse_motion(self, x, y, dx, dy): """ Handle Mouse Motion """ # Move the center of the player sprite to match the mouse x, y self.player_sprite.center_x = x self.player_sprite.center_y = y def on_update(self, delta_time): """ Movement and game logic """ for coin in self.coin_list: coin.follow_sprite(self.player_sprite) # Generate a list of all sprites that collided with the player. hit_list = arcade.check_for_collision_with_list(self.player_sprite, self.coin_list) # Loop through each colliding sprite, remove it, and add to the score. for coin in hit_list: coin.kill() self.score += 1 def main(): """ Main method """ window = MyGame() window.setup() arcade.run() if __name__ == "__main__": main() ```