Creating a Depth First Maze

Screen shot of a maze created by depth first
maze_depth_first.py
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"""
Create a maze using a depth-first search maze generation algorithm.
For more information on this algorithm see:
http://www.algosome.com/articles/maze-generation-depth-first.html
...or search up some other examples.

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.maze_depth_first
"""
import random
import arcade
import timeit
import os

NATIVE_SPRITE_SIZE = 128
SPRITE_SCALING = 0.25
SPRITE_SIZE = NATIVE_SPRITE_SIZE * SPRITE_SCALING

SCREEN_WIDTH = 1000
SCREEN_HEIGHT = 700

MOVEMENT_SPEED = 8

TILE_EMPTY = 0
TILE_CRATE = 1

# Maze must have an ODD number of rows and columns.
# Walls go on EVEN rows/columns.
# Openings go on ODD rows/columns
MAZE_HEIGHT = 51
MAZE_WIDTH = 51

MERGE_SPRITES = True

# How many pixels to keep as a minimum margin between the character
# and the edge of the screen.
VIEWPORT_MARGIN = 200


def _create_grid_with_cells(width, height):
    """ Create a grid with empty cells on odd row/column combinations. """
    grid = []
    for row in range(height):
        grid.append([])
        for column in range(width):
            if column % 2 == 1 and row % 2 == 1:
                grid[row].append(TILE_EMPTY)
            elif column == 0 or row == 0 or column == width - 1 or row == height - 1:
                grid[row].append(TILE_CRATE)
            else:
                grid[row].append(TILE_CRATE)
    return grid


def make_maze_depth_first(maze_width, maze_height):
    maze = _create_grid_with_cells(maze_width, maze_height)

    w = (len(maze[0]) - 1) // 2
    h = (len(maze) - 1) // 2
    vis = [[0] * w + [1] for _ in range(h)] + [[1] * (w + 1)]

    def walk(x, y):
        vis[y][x] = 1

        d = [(x - 1, y), (x, y + 1), (x + 1, y), (x, y - 1)]
        random.shuffle(d)
        for (xx, yy) in d:
            if vis[yy][xx]:
                continue
            if xx == x:
                maze[max(y, yy) * 2][x * 2 + 1] = TILE_EMPTY
            if yy == y:
                maze[y * 2 + 1][max(x, xx) * 2] = TILE_EMPTY

            walk(xx, yy)

    walk(random.randrange(w), random.randrange(h))

    return maze


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

    def __init__(self, width, height):
        """
        Initializer
        """
        super().__init__(width, height)

        # 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)

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

        # Player info
        self.score = 0
        self.player_sprite = None

        # Physics engine
        self.physics_engine = None

        # Used to scroll
        self.view_bottom = 0
        self.view_left = 0

        # Time to process
        self.processing_time = 0
        self.draw_time = 0

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

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

        self.score = 0

        # Create the maze
        maze = make_maze_depth_first(MAZE_WIDTH, MAZE_HEIGHT)

        # Create sprites based on 2D grid
        if not MERGE_SPRITES:
            # This is the simple-to-understand method. Each grid location
            # is a sprite.
            for row in range(MAZE_HEIGHT):
                for column in range(MAZE_WIDTH):
                    if maze[row][column] == 1:
                        wall = arcade.Sprite("images/grassCenter.png", SPRITE_SCALING)
                        wall.center_x = column * SPRITE_SIZE + SPRITE_SIZE / 2
                        wall.center_y = row * SPRITE_SIZE + SPRITE_SIZE / 2
                        self.wall_list.append(wall)
        else:
            # This uses new Arcade 1.3.1 features, that allow me to create a
            # larger sprite with a repeating texture. So if there are multiple
            # cells in a row with a wall, we merge them into one sprite, with a
            # repeating texture for each cell. This reduces our sprite count.
            for row in range(MAZE_HEIGHT):
                column = 0
                while column < len(maze):
                    while column < len(maze) and maze[row][column] == 0:
                        column += 1
                    start_column = column
                    while column < len(maze) and maze[row][column] == 1:
                        column += 1
                    end_column = column - 1

                    column_count = end_column - start_column + 1
                    column_mid = (start_column + end_column) / 2

                    wall = arcade.Sprite("images/grassCenter.png", SPRITE_SCALING,
                                         repeat_count_x=column_count)
                    wall.center_x = column_mid * SPRITE_SIZE + SPRITE_SIZE / 2
                    wall.center_y = row * SPRITE_SIZE + SPRITE_SIZE / 2
                    wall.width = SPRITE_SIZE * column_count
                    self.wall_list.append(wall)

        # Set up the player
        self.player_sprite = arcade.Sprite("images/character.png", SPRITE_SCALING)
        self.player_list.append(self.player_sprite)

        # Randomly place the player. If we are in a wall, repeat until we aren't.
        placed = False
        while not placed:

            # Randomly position
            self.player_sprite.center_x = random.randrange(MAZE_WIDTH * SPRITE_SIZE)
            self.player_sprite.center_y = random.randrange(MAZE_HEIGHT * SPRITE_SIZE)

            # Are we in a wall?
            walls_hit = arcade.check_for_collision_with_list(self.player_sprite, self.wall_list)
            if len(walls_hit) == 0:
                # Not in a wall! Success!
                placed = True

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

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

        # Set the viewport boundaries
        # These numbers set where we have 'scrolled' to.
        self.view_left = 0
        self.view_bottom = 0
        print(f"Total wall blocks: {len(self.wall_list)}")

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

        # This command has to happen before we start drawing
        arcade.start_render()

        # Start timing how long this takes
        draw_start_time = timeit.default_timer()

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

        # Draw info on the screen
        sprite_count = len(self.wall_list)

        output = f"Sprite Count: {sprite_count}"
        arcade.draw_text(output,
                         self.view_left + 20,
                         SCREEN_HEIGHT - 20 + self.view_bottom,
                         arcade.color.WHITE, 16)

        output = f"Drawing time: {self.draw_time:.3f}"
        arcade.draw_text(output,
                         self.view_left + 20,
                         SCREEN_HEIGHT - 40 + self.view_bottom,
                         arcade.color.WHITE, 16)

        output = f"Processing time: {self.processing_time:.3f}"
        arcade.draw_text(output,
                         self.view_left + 20,
                         SCREEN_HEIGHT - 60 + self.view_bottom,
                         arcade.color.WHITE, 16)

        self.draw_time = timeit.default_timer() - draw_start_time

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

        if key == arcade.key.UP:
            self.player_sprite.change_y = MOVEMENT_SPEED
        elif key == arcade.key.DOWN:
            self.player_sprite.change_y = -MOVEMENT_SPEED
        elif key == arcade.key.LEFT:
            self.player_sprite.change_x = -MOVEMENT_SPEED
        elif key == arcade.key.RIGHT:
            self.player_sprite.change_x = 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 update(self, delta_time):
        """ Movement and game logic """

        start_time = timeit.default_timer()

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

        # --- Manage Scrolling ---

        # Track if we need to change the viewport

        changed = False

        # Scroll left
        left_bndry = self.view_left + VIEWPORT_MARGIN
        if self.player_sprite.left < left_bndry:
            self.view_left -= left_bndry - self.player_sprite.left
            changed = True

        # Scroll right
        right_bndry = self.view_left + SCREEN_WIDTH - VIEWPORT_MARGIN
        if self.player_sprite.right > right_bndry:
            self.view_left += self.player_sprite.right - right_bndry
            changed = True

        # Scroll up
        top_bndry = self.view_bottom + SCREEN_HEIGHT - VIEWPORT_MARGIN
        if self.player_sprite.top > top_bndry:
            self.view_bottom += self.player_sprite.top - top_bndry
            changed = True

        # Scroll down
        bottom_bndry = self.view_bottom + VIEWPORT_MARGIN
        if self.player_sprite.bottom < bottom_bndry:
            self.view_bottom -= bottom_bndry - self.player_sprite.bottom
            changed = True

        if changed:
            arcade.set_viewport(self.view_left,
                                SCREEN_WIDTH + self.view_left,
                                self.view_bottom,
                                SCREEN_HEIGHT + self.view_bottom)

        # Save the time it took to do this.
        self.processing_time = timeit.default_timer() - start_time


def main():
    """ Main method """
    window = MyGame(SCREEN_WIDTH, SCREEN_HEIGHT)
    window.setup()
    arcade.run()


if __name__ == "__main__":
    main()