Step 10 - Multiple Levels and Other Layers#

Now that we’ve seen the basics of loading a Tiled map, we’ll give another example with some more features. In this example we’ll add the following things:

  • New layers including foreground, background, and “Don’t Touch”

    • The background layer will appear behind the player

    • The foreground layer will appear in front of the player

    • The Don’t Touch layer will cause the player to be reset to the start

  • The player resets to the start if they fall off the map

  • If the player gets to the right side of the map, the program attempts to load the next map

    • This is achieved by naming the maps with incrementing numbers, something like “map_01.json”, “map_02.json”, etc. Then having a level attribute to track which number we’re on and increasing it and re-running the setup function.

To start things off, let’s add a few constants at the top of our game. The first one we need to define is the size of a sprite in pixels. Along with that we need to know the grid size in pixels. These are used to calculate the end of the level.

Multiple Levels - Constants#
SPRITE_PIXEL_SIZE = 128
GRID_PIXEL_SIZE = SPRITE_PIXEL_SIZE * TILE_SCALING

Next we need to define a starting position for the player, and then since we’re starting to have a larger number of layers in our game, it will be best to store their names in variables in case we need to change them later.

Multiple Levels - Constants#
# Player starting position
PLAYER_START_X = 64
PLAYER_START_Y = 225

# Layer Names from our TileMap
LAYER_NAME_PLATFORMS = "Platforms"
LAYER_NAME_COINS = "Coins"
LAYER_NAME_FOREGROUND = "Foreground"
LAYER_NAME_BACKGROUND = "Background"
LAYER_NAME_DONT_TOUCH = "Don't Touch"

Then in the __init__ function we’ll add two new values. One to know where the right edge of the map is, and one to keep track of what level we’re on, and add a new game over sound.

Multiple Levels - Init Function#
        # Where is the right edge of the map?
        self.end_of_map = 0

        # Level
        self.level = 1

        # Load sounds
        self.collect_coin_sound = arcade.load_sound(":resources:sounds/coin1.wav")
        self.jump_sound = arcade.load_sound(":resources:sounds/jump1.wav")
        self.game_over = arcade.load_sound(":resources:sounds/gameover1.wav")

Also in our __init__ function we’ll need a variable to tell us if we need to reset the score. This will be the case if the player fails the level. However, now that the player can pass a level, we need to keep the score when calling our setup function for the new level. Otherwise it will reset the score back to 0

Multiple Levels - Init Function#
        # Do we need to reset the score?
        self.reset_score = True

Then in our setup function we’ll change up our map name variable to use that new level attribute, and add some extra layer specific options for the new layers we’ve added to our map.

Multiple Levels - Setup Function#
        # Map name
        map_name = f":resources:tiled_maps/map2_level_{self.level}.json"

        # Layer Specific Options for the Tilemap
        layer_options = {
            LAYER_NAME_PLATFORMS: {
                "use_spatial_hash": True,
            },
            LAYER_NAME_COINS: {
                "use_spatial_hash": True,
            },
            LAYER_NAME_DONT_TOUCH: {
                "use_spatial_hash": True,
            },
        }

Now in order to make our player appear behind the “Foreground” layer, we need to add a line in our setup function before we create the player Sprite. This will basically be telling our Scene where in the render order we want to place the player. Previously we haven’t defined this, and so it’s always just been added to the end of the render order.

Multiple Levels - Setup Function#
        # Add Player Spritelist before "Foreground" layer. This will make the foreground
        # be drawn after the player, making it appear to be in front of the Player.
        # Setting before using scene.add_sprite allows us to define where the SpriteList
        # will be in the draw order. If we just use add_sprite, it will be appended to the
        # end of the order.
        self.scene.add_sprite_list_after("Player", LAYER_NAME_FOREGROUND)

        # Set up the player, specifically placing it at these coordinates.
        image_source = ":resources:images/animated_characters/female_adventurer/femaleAdventurer_idle.png"
        self.player_sprite = arcade.Sprite(image_source, CHARACTER_SCALING)
        self.player_sprite.center_x = PLAYER_START_X
        self.player_sprite.center_y = PLAYER_START_Y
        self.scene.add_sprite("Player", self.player_sprite)

Next in our setup function we need to check to see if we need to reset the score or keep it.

Multiple Levels - Setup Function#
        # Initiate New Scene with our TileMap, this will automatically add all layers
        # from the map as SpriteLists in the scene in the proper order.
        self.scene = arcade.Scene.from_tilemap(self.tile_map)

        # Keep track of the score, make sure we keep the score if the player finishes a level
        if self.reset_score:
            self.score = 0
        self.reset_score = True

Lastly in our setup function we need to calculate the end_of_map value we added earlier in init.

Multiple Levels - Setup Function#
        # Calculate the right edge of the my_map in pixels
        self.end_of_map = self.tile_map.width * GRID_PIXEL_SIZE

The on_draw, on_key_press, and on_key_release functions will be unchanged for this section, so the last thing to do is add a few things to the on_update function. First we check if the player has fallen off of the map, and if so, we move them back to the starting position. Then we check if they collided with something from the “Don’t Touch” layer, and if so reset them to the start. Lastly we check if they’ve reached the end of the map, and if they have we increment the level value, tell our setup function not to reset the score, and then re-run the setup function.

Multiple Levels - Update Function#
        # Did the player fall off the map?
        if self.player_sprite.center_y < -100:
            self.player_sprite.center_x = PLAYER_START_X
            self.player_sprite.center_y = PLAYER_START_Y

            arcade.play_sound(self.game_over)

        # Did the player touch something they should not?
        if arcade.check_for_collision_with_list(
            self.player_sprite, self.scene[LAYER_NAME_DONT_TOUCH]
        ):
            self.player_sprite.change_x = 0
            self.player_sprite.change_y = 0
            self.player_sprite.center_x = PLAYER_START_X
            self.player_sprite.center_y = PLAYER_START_Y

            arcade.play_sound(self.game_over)

        # See if the user got to the end of the level
        if self.player_sprite.center_x >= self.end_of_map:
            # Advance to the next level
            self.level += 1

            # Make sure to keep the score from this level when setting up the next level
            self.reset_score = False

            # Load the next level
            self.setup()

Source Code#

Multiple Levels#
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"""
Platformer Game
"""
import arcade

# Constants
SCREEN_WIDTH = 1000
SCREEN_HEIGHT = 650
SCREEN_TITLE = "Platformer"

# Constants used to scale our sprites from their original size
CHARACTER_SCALING = 1
TILE_SCALING = 0.5
COIN_SCALING = 0.5
SPRITE_PIXEL_SIZE = 128
GRID_PIXEL_SIZE = SPRITE_PIXEL_SIZE * TILE_SCALING

# Movement speed of player, in pixels per frame
PLAYER_MOVEMENT_SPEED = 10
GRAVITY = 1
PLAYER_JUMP_SPEED = 20

# Player starting position
PLAYER_START_X = 64
PLAYER_START_Y = 225

# Layer Names from our TileMap
LAYER_NAME_PLATFORMS = "Platforms"
LAYER_NAME_COINS = "Coins"
LAYER_NAME_FOREGROUND = "Foreground"
LAYER_NAME_BACKGROUND = "Background"
LAYER_NAME_DONT_TOUCH = "Don't Touch"


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

    def __init__(self):

        # Call the parent class and set up the window
        super().__init__(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)

        # Our TileMap Object
        self.tile_map = None

        # Our Scene Object
        self.scene = None

        # Separate variable that holds the player sprite
        self.player_sprite = None

        # Our physics engine
        self.physics_engine = None

        # A Camera that can be used for scrolling the screen
        self.camera = None

        # A Camera that can be used to draw GUI elements
        self.gui_camera = None

        # Keep track of the score
        self.score = 0

        # Do we need to reset the score?
        self.reset_score = True

        # Where is the right edge of the map?
        self.end_of_map = 0

        # Level
        self.level = 1

        # Load sounds
        self.collect_coin_sound = arcade.load_sound(":resources:sounds/coin1.wav")
        self.jump_sound = arcade.load_sound(":resources:sounds/jump1.wav")
        self.game_over = arcade.load_sound(":resources:sounds/gameover1.wav")

    def setup(self):
        """Set up the game here. Call this function to restart the game."""

        # Set up the Cameras
        self.camera = arcade.Camera(self.width, self.height)
        self.gui_camera = arcade.Camera(self.width, self.height)

        # Map name
        map_name = f":resources:tiled_maps/map2_level_{self.level}.json"

        # Layer Specific Options for the Tilemap
        layer_options = {
            LAYER_NAME_PLATFORMS: {
                "use_spatial_hash": True,
            },
            LAYER_NAME_COINS: {
                "use_spatial_hash": True,
            },
            LAYER_NAME_DONT_TOUCH: {
                "use_spatial_hash": True,
            },
        }

        # Load in TileMap
        self.tile_map = arcade.load_tilemap(map_name, TILE_SCALING, layer_options)

        # Initiate New Scene with our TileMap, this will automatically add all layers
        # from the map as SpriteLists in the scene in the proper order.
        self.scene = arcade.Scene.from_tilemap(self.tile_map)

        # Keep track of the score, make sure we keep the score if the player finishes a level
        if self.reset_score:
            self.score = 0
        self.reset_score = True

        # Add Player Spritelist before "Foreground" layer. This will make the foreground
        # be drawn after the player, making it appear to be in front of the Player.
        # Setting before using scene.add_sprite allows us to define where the SpriteList
        # will be in the draw order. If we just use add_sprite, it will be appended to the
        # end of the order.
        self.scene.add_sprite_list_after("Player", LAYER_NAME_FOREGROUND)

        # Set up the player, specifically placing it at these coordinates.
        image_source = ":resources:images/animated_characters/female_adventurer/femaleAdventurer_idle.png"
        self.player_sprite = arcade.Sprite(image_source, CHARACTER_SCALING)
        self.player_sprite.center_x = PLAYER_START_X
        self.player_sprite.center_y = PLAYER_START_Y
        self.scene.add_sprite("Player", self.player_sprite)

        # --- Load in a map from the tiled editor ---

        # Calculate the right edge of the my_map in pixels
        self.end_of_map = self.tile_map.width * GRID_PIXEL_SIZE

        # --- Other stuff
        # Set the background color
        if self.tile_map.background_color:
            arcade.set_background_color(self.tile_map.background_color)

        # Create the 'physics engine'
        self.physics_engine = arcade.PhysicsEnginePlatformer(
            self.player_sprite,
            gravity_constant=GRAVITY,
            walls=self.scene[LAYER_NAME_PLATFORMS],
        )

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

        # Clear the screen to the background color
        self.clear()

        # Activate the game camera
        self.camera.use()

        # Draw our Scene
        self.scene.draw()

        # Activate the GUI camera before drawing GUI elements
        self.gui_camera.use()

        # Draw our score on the screen, scrolling it with the viewport
        score_text = f"Score: {self.score}"
        arcade.draw_text(
            score_text,
            10,
            10,
            arcade.csscolor.BLACK,
            18,
        )

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

        if key == arcade.key.UP or key == arcade.key.W:
            if self.physics_engine.can_jump():
                self.player_sprite.change_y = PLAYER_JUMP_SPEED
                arcade.play_sound(self.jump_sound)
        elif key == arcade.key.LEFT or key == arcade.key.A:
            self.player_sprite.change_x = -PLAYER_MOVEMENT_SPEED
        elif key == arcade.key.RIGHT or key == arcade.key.D:
            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.LEFT or key == arcade.key.A:
            self.player_sprite.change_x = 0
        elif key == arcade.key.RIGHT or key == arcade.key.D:
            self.player_sprite.change_x = 0

    def center_camera_to_player(self):
        screen_center_x = self.player_sprite.center_x - (self.camera.viewport_width / 2)
        screen_center_y = self.player_sprite.center_y - (
            self.camera.viewport_height / 2
        )
        if screen_center_x < 0:
            screen_center_x = 0
        if screen_center_y < 0:
            screen_center_y = 0
        player_centered = screen_center_x, screen_center_y

        self.camera.move_to(player_centered)

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

        # Move the player with the physics engine
        self.physics_engine.update()

        # See if we hit any coins
        coin_hit_list = arcade.check_for_collision_with_list(
            self.player_sprite, self.scene[LAYER_NAME_COINS]
        )

        # Loop through each coin we hit (if any) and remove it
        for coin in coin_hit_list:
            # Remove the coin
            coin.remove_from_sprite_lists()
            # Play a sound
            arcade.play_sound(self.collect_coin_sound)
            # Add one to the score
            self.score += 1

        # Did the player fall off the map?
        if self.player_sprite.center_y < -100:
            self.player_sprite.center_x = PLAYER_START_X
            self.player_sprite.center_y = PLAYER_START_Y

            arcade.play_sound(self.game_over)

        # Did the player touch something they should not?
        if arcade.check_for_collision_with_list(
            self.player_sprite, self.scene[LAYER_NAME_DONT_TOUCH]
        ):
            self.player_sprite.change_x = 0
            self.player_sprite.change_y = 0
            self.player_sprite.center_x = PLAYER_START_X
            self.player_sprite.center_y = PLAYER_START_Y

            arcade.play_sound(self.game_over)

        # See if the user got to the end of the level
        if self.player_sprite.center_x >= self.end_of_map:
            # Advance to the next level
            self.level += 1

            # Make sure to keep the score from this level when setting up the next level
            self.reset_score = False

            # Load the next level
            self.setup()

        # Position the camera
        self.center_camera_to_player()


def main():
    """Main function"""
    window = MyGame()
    window.setup()
    arcade.run()


if __name__ == "__main__":
    main()