A-Star Path Finding

A-Star Path Finding
astar_pathfinding.py
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"""
A-Star Path-finding

.. note:: This uses features from the upcoming version 2.4. The API for these
          functions may still change. To use, you will need to install one of the
          pre-release packages, or install via GitHub.

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.astar_pathfinding
"""

import arcade
import os
import random

SPRITE_IMAGE_SIZE = 128
SPRITE_SCALING = 0.25
SPRITE_SIZE = SPRITE_IMAGE_SIZE * SPRITE_SCALING

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600
SCREEN_TITLE = "A-Star Path-finding"

MOVEMENT_SPEED = 5

VIEWPORT_MARGIN = 100


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

    def __init__(self, width, height, title):
        """
        Initializer
        """

        # Call the parent class initializer
        super().__init__(width, height, 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.wall_list = None
        self.enemy_list = None

        # Set up the player info
        self.player = None

        # Track the current state of what key is pressed
        self.left_pressed = False
        self.right_pressed = False
        self.up_pressed = False
        self.down_pressed = False

        self.physics_engine = None

        # --- Related to paths
        # List of points that makes up a path between two points
        self.path = None
        # List of points we checked to see if there is a barrier there
        self.barrier_list = None

        # Used in scrolling
        self.view_bottom = 0
        self.view_left = 0

        # Set the background color
        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.wall_list = arcade.SpriteList(use_spatial_hash=True, spatial_hash_cell_size=128)
        self.enemy_list = arcade.SpriteList()

        # Set up the player
        self.player = arcade.Sprite(":resources:images/animated_characters/female_person/femalePerson_idle.png", SPRITE_SCALING)
        self.player.center_x = SPRITE_SIZE * 5
        self.player.center_y = SPRITE_SIZE * 1
        self.player_list.append(self.player)

        # Set enemies
        enemy = arcade.Sprite(":resources:images/animated_characters/zombie/zombie_idle.png", SPRITE_SCALING)
        enemy.center_x = SPRITE_SIZE * 4
        enemy.center_y = SPRITE_SIZE * 7
        self.enemy_list.append(enemy)

        spacing = SPRITE_SIZE * 3
        for column in range(10):
            for row in range(15):
                sprite = arcade.Sprite(":resources:images/tiles/grassCenter.png", SPRITE_SCALING)

                x = (column + 1) * spacing
                y = (row + 1) * sprite.height

                sprite.center_x = x
                sprite.center_y = y
                if random.randrange(100) > 30:
                    self.wall_list.append(sprite)

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

        # --- Path related
        # This variable holds the travel-path. We keep it as an attribute so
        # we can calculate it in on_update, and draw it in on_draw.
        self.path = None
        # Grid size for calculations. The smaller the grid, the longer the time
        # for calculations. Make sure the grid aligns with the sprite wall grid,
        # or some openings might be missed.
        grid_size = SPRITE_SIZE

        # Calculate the playing field size. We can't generate paths outside of
        # this.
        playing_field_left_boundary = -SPRITE_SIZE * 2
        playing_field_right_boundary = SPRITE_SIZE * 35
        playing_field_top_boundary = SPRITE_SIZE * 17
        playing_field_bottom_boundary = -SPRITE_SIZE * 2

        # This calculates a list of barriers. By calculating it here in the
        # init, we are assuming this list does not change. In this example,
        # our walls don't move, so that is ok. If we want moving barriers (such as
        # moving platforms or enemies) we need to recalculate. This can be an
        # time-intensive process depending on the playing field size and grid
        # resolution.

        # Note: If the enemy sprites are the same size, we only need to calculate
        # one of these. We do NOT need a different one for each enemy. The sprite
        # is just used for a size calculation.
        self.barrier_list = arcade.AStarBarrierList(enemy,
                                                    self.wall_list,
                                                    grid_size,
                                                    playing_field_left_boundary,
                                                    playing_field_right_boundary,
                                                    playing_field_bottom_boundary,
                                                    playing_field_top_boundary)

    def on_draw(self):
        """
        Render the screen.
        """
        try:
            # This command has to happen before we start drawing
            arcade.start_render()

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

            if self.path:
                arcade.draw_line_strip(self.path, arcade.color.BLUE, 2)

        except Exception:

            import traceback
            traceback.print_exc()

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

        try:
            # Calculate speed based on the keys pressed
            self.player.change_x = 0
            self.player.change_y = 0

            if self.up_pressed and not self.down_pressed:
                self.player.change_y = MOVEMENT_SPEED
            elif self.down_pressed and not self.up_pressed:
                self.player.change_y = -MOVEMENT_SPEED
            if self.left_pressed and not self.right_pressed:
                self.player.change_x = -MOVEMENT_SPEED
            elif self.right_pressed and not self.left_pressed:
                self.player.change_x = MOVEMENT_SPEED

            # Update the character
            self.physics_engine.update()

            # Calculate a path to the player
            enemy = self.enemy_list[0]
            # Set to True if we can move diagonally. Note that diagnonal movement
            # might cause the enemy to clip corners.
            self.path = arcade.astar_calculate_path(enemy.position,
                                                    self.player.position,
                                                    self.barrier_list,
                                                    diagonal_movement=False)
                # print(self.path,"->", self.player.position)

            # --- Manage Scrolling ---

            # Keep track of if we changed the boundary. We don't want to call the
            # set_viewport command if we didn't change the view port.
            changed = False

            # Scroll left
            left_boundary = self.view_left + VIEWPORT_MARGIN
            if self.player.left < left_boundary:
                self.view_left -= left_boundary - self.player.left
                changed = True

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

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

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

            # Make sure our boundaries are integer values. While the view port does
            # support floating point numbers, for this application we want every pixel
            # in the view port to map directly onto a pixel on the screen. We don't want
            # any rounding errors.
            self.view_left = int(self.view_left)
            self.view_bottom = int(self.view_bottom)

            # If we changed the boundary values, update the view port to match
            if changed:
                arcade.set_viewport(self.view_left,
                                    SCREEN_WIDTH + self.view_left,
                                    self.view_bottom,
                                    SCREEN_HEIGHT + self.view_bottom)

        except Exception:
            import traceback
            traceback.print_exc()

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

        if key == arcade.key.UP:
            self.up_pressed = True
        elif key == arcade.key.DOWN:
            self.down_pressed = True
        elif key == arcade.key.LEFT:
            self.left_pressed = True
        elif key == arcade.key.RIGHT:
            self.right_pressed = True

    def on_key_release(self, key, modifiers):
        """Called when the user releases a key. """

        if key == arcade.key.UP:
            self.up_pressed = False
        elif key == arcade.key.DOWN:
            self.down_pressed = False
        elif key == arcade.key.LEFT:
            self.left_pressed = False
        elif key == arcade.key.RIGHT:
            self.right_pressed = False


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


if __name__ == "__main__":
    main()