Platformer Template

Quickly get started creating your own platformer!

Screenshot of platformer template

About This Template

This is a template to get you started coding a side-scrolling platformer as quickly as possible. I recommend the following steps:

  1. Create a folder to hold the code. Copy this example to that folder, and call it main.py.

  2. Make sure the example code runs fine.

  3. Copy the tile images you want to use to a subdirectory of the folder that holds your code.

  4. Create a very simple Tiled Map using the Tiled Map Editor. I suggest just creating a floor and nothing else. For more detail on how to create a tiled map, see Step 9 - Use Tiled Map Editor.

  5. Save the file to the same directory as your source code. If you create a separate tileset, also save it to the same directory as your code.

  6. Update the code to load your file instead of the map.

  7. Test and make sure it works.

  8. Now that you are sure things work, make your own platformer!

Warning

Watch the directories!

One of the most frequent mistakes is to save maps and tile sets to a directory that isn’t the same directory as your code. Or to not have the tile images in that folder. If everything isn’t in the same folder (or a subfolder of that) it is hard to package it up later.

For more detailed instructions, see the tutorial Simple Platformer.

Source Code

template_platformer.py
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"""
Platformer Template
"""
import arcade

# --- Constants
SCREEN_TITLE = "Platformer"

SCREEN_WIDTH = 1000
SCREEN_HEIGHT = 650

# 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


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, resizable=True)

        # 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_sprites = None

        # A non-scrolling camera that can be used to draw GUI elements
        self.camera_gui = None

        # Keep track of the score
        self.score = 0

        # What key is pressed down?
        self.left_key_down = False
        self.right_key_down = False

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

        # Setup the Cameras
        self.camera_sprites = arcade.Camera(self.width, self.height)
        self.camera_gui = arcade.Camera(self.width, self.height)

        # Name of map file to load
        map_name = ":resources:tiled_maps/map.json"

        # Layer specific options are defined based on Layer names in a dictionary
        # Doing this will make the SpriteList for the platforms layer
        # use spatial hashing for detection.
        layer_options = {
            "Platforms": {
                "use_spatial_hash": True,
            },
        }

        # Read in the tiled map
        self.tile_map = arcade.load_tilemap(map_name, TILE_SCALING, layer_options)

        # Initialize 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)

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

        # Keep track of the score
        self.score = 0

        # Set up the player, specifically placing it at these coordinates.
        src = ":resources:images/animated_characters/female_adventurer/femaleAdventurer_idle.png"
        self.player_sprite = arcade.Sprite(src, CHARACTER_SCALING)
        self.player_sprite.center_x = 128
        self.player_sprite.center_y = 128
        self.scene.add_sprite("Player", self.player_sprite)

        # --- Other stuff
        # Create the 'physics engine'
        self.physics_engine = arcade.PhysicsEnginePlatformer(
            self.player_sprite, gravity_constant=GRAVITY, walls=self.scene["Platforms"]
        )

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

        # Clear the screen to the background color
        arcade.start_render()

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

        # Draw our Scene
        # Note, if you a want pixelated look, add pixelated=True to the parameters
        self.scene.draw()

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

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

    def update_player_speed(self):

        # Calculate speed based on the keys pressed
        self.player_sprite.change_x = 0

        if self.left_key_down and not self.right_key_down:
            self.player_sprite.change_x = -PLAYER_MOVEMENT_SPEED
        elif self.right_key_down and not self.left_key_down:
            self.player_sprite.change_x = PLAYER_MOVEMENT_SPEED

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

        # Jump
        if key == arcade.key.UP or key == arcade.key.W:
            if self.physics_engine.can_jump():
                self.player_sprite.change_y = PLAYER_JUMP_SPEED

        # Left
        elif key == arcade.key.LEFT or key == arcade.key.A:
            self.left_key_down = True
            self.update_player_speed()

        # Right
        elif key == arcade.key.RIGHT or key == arcade.key.D:
            self.right_key_down = True
            self.update_player_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.left_key_down = False
            self.update_player_speed()
        elif key == arcade.key.RIGHT or key == arcade.key.D:
            self.right_key_down = False
            self.update_player_speed()

    def center_camera_to_player(self):
        # Find where player is, then calculate lower left corner from that
        screen_center_x = self.player_sprite.center_x - (self.camera_sprites.viewport_width / 2)
        screen_center_y = self.player_sprite.center_y - (self.camera_sprites.viewport_height / 2)

        # Set some limits on how far we scroll
        if screen_center_x < 0:
            screen_center_x = 0
        if screen_center_y < 0:
            screen_center_y = 0

        # Here's our center, move to it
        player_centered = screen_center_x, screen_center_y
        self.camera_sprites.move_to(player_centered)

    def on_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["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()
            # Add one to the score
            self.score += 1

        # Position the camera
        self.center_camera_to_player()

    def on_resize(self, width, height):
        """ Resize window """
        self.camera_sprites.resize(int(width), int(height))
        self.camera_gui.resize(int(width), int(height))


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


if __name__ == "__main__":
    main()