pymunk_demo_platformer_10.py Full Listing

pymunk_demo_platformer_10.py
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"""
Example of Pymunk Physics Engine Platformer
"""
import math
from typing import Optional
import arcade

SCREEN_TITLE = "PyMunk Platformer"

# How big are our image tiles?
SPRITE_IMAGE_SIZE = 128

# Scale sprites up or down
SPRITE_SCALING_PLAYER = 0.5
SPRITE_SCALING_TILES = 0.5

# Scaled sprite size for tiles
SPRITE_SIZE = int(SPRITE_IMAGE_SIZE * SPRITE_SCALING_PLAYER)

# Size of grid to show on screen, in number of tiles
SCREEN_GRID_WIDTH = 25
SCREEN_GRID_HEIGHT = 15

# Size of screen to show, in pixels
SCREEN_WIDTH = SPRITE_SIZE * SCREEN_GRID_WIDTH
SCREEN_HEIGHT = SPRITE_SIZE * SCREEN_GRID_HEIGHT

# --- Physics forces. Higher number, faster accelerating.

# Gravity
GRAVITY = 1500

# Damping - Amount of speed lost per second
DEFAULT_DAMPING = 1.0
PLAYER_DAMPING = 0.4

# Friction between objects
PLAYER_FRICTION = 1.0
WALL_FRICTION = 0.7
DYNAMIC_ITEM_FRICTION = 0.6

# Mass (defaults to 1)
PLAYER_MASS = 2.0

# Keep player from going too fast
PLAYER_MAX_HORIZONTAL_SPEED = 450
PLAYER_MAX_VERTICAL_SPEED = 1600

# Force applied while on the ground
PLAYER_MOVE_FORCE_ON_GROUND = 8000

# Force applied when moving left/right in the air
PLAYER_MOVE_FORCE_IN_AIR = 900

# Strength of a jump
PLAYER_JUMP_IMPULSE = 1800

# Close enough to not-moving to have the animation go to idle.
DEAD_ZONE = 0.1

# Constants used to track if the player is facing left or right
RIGHT_FACING = 0
LEFT_FACING = 1

# How many pixels to move before we change the texture in the walking animation
DISTANCE_TO_CHANGE_TEXTURE = 20

# How much force to put on the bullet
BULLET_MOVE_FORCE = 4500

# Mass of the bullet
BULLET_MASS = 0.1

# Make bullet less affected by gravity
BULLET_GRAVITY = 300

class PlayerSprite(arcade.Sprite):
    """ Player Sprite """
    def __init__(self):
        """ Init """
        # Let parent initialize
        super().__init__()

        # Set our scale
        self.scale = SPRITE_SCALING_PLAYER

        # Images from Kenney.nl's Character pack
        # main_path = ":resources:images/animated_characters/female_adventurer/femaleAdventurer"
        main_path = ":resources:images/animated_characters/female_person/femalePerson"
        # main_path = ":resources:images/animated_characters/male_person/malePerson"
        # main_path = ":resources:images/animated_characters/male_adventurer/maleAdventurer"
        # main_path = ":resources:images/animated_characters/zombie/zombie"
        # main_path = ":resources:images/animated_characters/robot/robot"

        # Load textures for idle standing
        self.idle_texture_pair = arcade.load_texture_pair(f"{main_path}_idle.png")
        self.jump_texture_pair = arcade.load_texture_pair(f"{main_path}_jump.png")
        self.fall_texture_pair = arcade.load_texture_pair(f"{main_path}_fall.png")

        # Load textures for walking
        self.walk_textures = []
        for i in range(8):
            texture = arcade.load_texture_pair(f"{main_path}_walk{i}.png")
            self.walk_textures.append(texture)

        # Set the initial texture
        self.texture = self.idle_texture_pair[0]

        # Hit box will be set based on the first image used.
        self.hit_box = self.texture.hit_box_points

        # Default to face-right
        self.character_face_direction = RIGHT_FACING

        # Index of our current texture
        self.cur_texture = 0

        # How far have we traveled horizontally since changing the texture
        self.x_odometer = 0

    def pymunk_moved(self, physics_engine, dx, dy, d_angle):
        """ Handle being moved by the pymunk engine """
        # Figure out if we need to face left or right
        if dx < -DEAD_ZONE and self.character_face_direction == RIGHT_FACING:
            self.character_face_direction = LEFT_FACING
        elif dx > DEAD_ZONE and self.character_face_direction == LEFT_FACING:
            self.character_face_direction = RIGHT_FACING

        # Are we on the ground?
        is_on_ground = physics_engine.is_on_ground(self)

        # Add to the odometer how far we've moved
        self.x_odometer += dx

        # Jumping animation
        if not is_on_ground:
            if dy > DEAD_ZONE:
                self.texture = self.jump_texture_pair[self.character_face_direction]
                return
            elif dy < -DEAD_ZONE:
                self.texture = self.fall_texture_pair[self.character_face_direction]
                return

        # Idle animation
        if abs(dx) <= DEAD_ZONE:
            self.texture = self.idle_texture_pair[self.character_face_direction]
            return

        # Have we moved far enough to change the texture?
        if abs(self.x_odometer) > DISTANCE_TO_CHANGE_TEXTURE:

            # Reset the odometer
            self.x_odometer = 0

            # Advance the walking animation
            self.cur_texture += 1
            if self.cur_texture > 7:
                self.cur_texture = 0
            self.texture = self.walk_textures[self.cur_texture][self.character_face_direction]

class BulletSprite(arcade.SpriteSolidColor):
    """ Bullet Sprite """
    def pymunk_moved(self, physics_engine, dx, dy, d_angle):
        """ Handle when the sprite is moved by the physics engine. """
        # If the bullet falls below the screen, remove it
        if self.center_y < -100:
            self.remove_from_sprite_lists()

class GameWindow(arcade.Window):
    """ Main Window """

    def __init__(self, width, height, title):
        """ Create the variables """

        # Init the parent class
        super().__init__(width, height, title)

        # Player sprite
        self.player_sprite: Optional[PlayerSprite] = None

        # Sprite lists we need
        self.player_list: Optional[arcade.SpriteList] = None
        self.wall_list: Optional[arcade.SpriteList] = None
        self.bullet_list: Optional[arcade.SpriteList] = None
        self.item_list: Optional[arcade.SpriteList] = None

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

        # Physics engine
        self.physics_engine = Optional[arcade.PymunkPhysicsEngine]

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

    def setup(self):
        """ Set up everything with the game """

        # Create the sprite lists
        self.player_list = arcade.SpriteList()
        self.bullet_list = arcade.SpriteList()

        # Read in the tiled map
        map_name = "pymunk_test_map.tmx"
        my_map = arcade.tilemap.read_tmx(map_name)

        # Read in the map layers
        self.wall_list = arcade.tilemap.process_layer(my_map, 'Platforms', SPRITE_SCALING_TILES)
        self.item_list = arcade.tilemap.process_layer(my_map, 'Dynamic Items', SPRITE_SCALING_TILES)

        # Create player sprite
        self.player_sprite = PlayerSprite()

        # Set player location
        grid_x = 1
        grid_y = 1
        self.player_sprite.center_x = SPRITE_SIZE * grid_x + SPRITE_SIZE / 2
        self.player_sprite.center_y = SPRITE_SIZE * grid_y + SPRITE_SIZE / 2
        # Add to player sprite list
        self.player_list.append(self.player_sprite)

        # --- Pymunk Physics Engine Setup ---

        # The default damping for every object controls the percent of velocity
        # the object will keep each second. A value of 1.0 is no speed loss,
        # 0.9 is 10% per second, 0.1 is 90% per second.
        # For top-down games, this is basically the friction for moving objects.
        # For platformers with gravity, this should probably be set to 1.0.
        # Default value is 1.0 if not specified.
        damping = DEFAULT_DAMPING

        # Set the gravity. (0, 0) is good for outer space and top-down.
        gravity = (0, -GRAVITY)

        # Create the physics engine
        self.physics_engine = arcade.PymunkPhysicsEngine(damping=damping,
                                                         gravity=gravity)

        def wall_hit_handler(bullet_sprite, _wall_sprite, _arbiter, _space, _data):
            """ Called for bullet/wall collision """
            bullet_sprite.remove_from_sprite_lists()

        self.physics_engine.add_collision_handler("bullet", "wall", post_handler=wall_hit_handler)

        def item_hit_handler(bullet_sprite, item_sprite, _arbiter, _space, _data):
            """ Called for bullet/wall collision """
            bullet_sprite.remove_from_sprite_lists()
            item_sprite.remove_from_sprite_lists()

        self.physics_engine.add_collision_handler("bullet", "item", post_handler=item_hit_handler)

        # Add the player.
        # For the player, we set the damping to a lower value, which increases
        # the damping rate. This prevents the character from traveling too far
        # after the player lets off the movement keys.
        # Setting the moment to PymunkPhysicsEngine.MOMENT_INF prevents it from
        # rotating.
        # Friction normally goes between 0 (no friction) and 1.0 (high friction)
        # Friction is between two objects in contact. It is important to remember
        # in top-down games that friction moving along the 'floor' is controlled
        # by damping.
        self.physics_engine.add_sprite(self.player_sprite,
                                       friction=PLAYER_FRICTION,
                                       mass=PLAYER_MASS,
                                       moment=arcade.PymunkPhysicsEngine.MOMENT_INF,
                                       collision_type="player",
                                       max_horizontal_velocity=PLAYER_MAX_HORIZONTAL_SPEED,
                                       max_vertical_velocity=PLAYER_MAX_VERTICAL_SPEED)

        # Create the walls.
        # By setting the body type to PymunkPhysicsEngine.STATIC the walls can't
        # move.
        # Movable objects that respond to forces are PymunkPhysicsEngine.DYNAMIC
        # PymunkPhysicsEngine.KINEMATIC objects will move, but are assumed to be
        # repositioned by code and don't respond to physics forces.
        # Dynamic is default.
        self.physics_engine.add_sprite_list(self.wall_list,
                                            friction=WALL_FRICTION,
                                            collision_type="wall",
                                            body_type=arcade.PymunkPhysicsEngine.STATIC)

        # Create the items
        self.physics_engine.add_sprite_list(self.item_list,
                                            friction=DYNAMIC_ITEM_FRICTION,
                                            collision_type="item")

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

        if key == arcade.key.LEFT:
            self.left_pressed = True
        elif key == arcade.key.RIGHT:
            self.right_pressed = True
        elif key == arcade.key.UP:
            # find out if player is standing on ground
            if self.physics_engine.is_on_ground(self.player_sprite):
                # She is! Go ahead and jump
                impulse = (0, PLAYER_JUMP_IMPULSE)
                self.physics_engine.apply_impulse(self.player_sprite, impulse)

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

        if key == arcade.key.LEFT:
            self.left_pressed = False
        elif key == arcade.key.RIGHT:
            self.right_pressed = False

    def on_mouse_press(self, x, y, button, modifiers):
        """ Called whenever the mouse button is clicked. """

        bullet = BulletSprite(20, 5, arcade.color.DARK_YELLOW)
        self.bullet_list.append(bullet)

        # Position the bullet at the player's current location
        start_x = self.player_sprite.center_x
        start_y = self.player_sprite.center_y
        bullet.position = self.player_sprite.position

        # Get from the mouse the destination location for the bullet
        # IMPORTANT! If you have a scrolling screen, you will also need
        # to add in self.view_bottom and self.view_left.
        dest_x = x
        dest_y = 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)

        # What is the 1/2 size of this sprite, so we can figure out how far
        # away to spawn the bullet
        size = max(self.player_sprite.width, self.player_sprite.height) / 2

        # Use angle to to spawn bullet away from player in proper direction
        bullet.center_x += size * math.cos(angle)
        bullet.center_y += size * math.sin(angle)

        # Set angle of bullet
        bullet.angle = math.degrees(angle)

        # Gravity to use for the bullet
        # If we don't use custom gravity, bullet drops too fast, or we have
        # to make it go too fast.
        # Force is in relation to bullet's angle.
        bullet_gravity = (0, -BULLET_GRAVITY)

        # Add the sprite. This needs to be done AFTER setting the fields above.
        self.physics_engine.add_sprite(bullet,
                                       mass=BULLET_MASS,
                                       damping=1.0,
                                       friction=0.6,
                                       collision_type="bullet",
                                       gravity=bullet_gravity,
                                       elasticity=0.9)

        # Add force to bullet
        force = (BULLET_MOVE_FORCE, 0)
        self.physics_engine.apply_force(bullet, force)

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

        is_on_ground = self.physics_engine.is_on_ground(self.player_sprite)
        # Update player forces based on keys pressed
        if self.left_pressed and not self.right_pressed:
            # Create a force to the left. Apply it.
            if is_on_ground:
                force = (-PLAYER_MOVE_FORCE_ON_GROUND, 0)
            else:
                force = (-PLAYER_MOVE_FORCE_IN_AIR, 0)
            self.physics_engine.apply_force(self.player_sprite, force)
            # Set friction to zero for the player while moving
            self.physics_engine.set_friction(self.player_sprite, 0)
        elif self.right_pressed and not self.left_pressed:
            # Create a force to the right. Apply it.
            if is_on_ground:
                force = (PLAYER_MOVE_FORCE_ON_GROUND, 0)
            else:
                force = (PLAYER_MOVE_FORCE_IN_AIR, 0)
            self.physics_engine.apply_force(self.player_sprite, force)
            # Set friction to zero for the player while moving
            self.physics_engine.set_friction(self.player_sprite, 0)
        else:
            # Player's feet are not moving. Therefore up the friction so we stop.
            self.physics_engine.set_friction(self.player_sprite, 1.0)

        # Move items in the physics engine
        self.physics_engine.step()

    def on_draw(self):
        """ Draw everything """
        arcade.start_render()
        self.wall_list.draw()
        self.bullet_list.draw()
        self.item_list.draw()
        self.player_list.draw()

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


if __name__ == "__main__":
    main()